Star Wars


                  The Science of Star Wars:
                  An Astrophysicist's Independent Examination of 
                  Space  Travel,  Aliens, Planets, and Robots 
                  As Portrayed in the Star Wars Films and Books

                             by Jeanne Cavelos



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                                 upload : 2.VI.2006

     ACKNOWLEDGMENTS I would like to  thank  my  research  assistant,  Keith
Maxwell, for his dedication and hard work. I honestly believe  he  can  find
valid scientific research on any topic, no matter how unusual. Keith was  an
invaluable help throughout the writing of this book. I would  also  like  to
thank the many scientists quoted within this  book,  who  graciously  shared
their time and expertise and brought their own fascinating  perspectives  to
the Star Wars universe . Special thanks to my Internet group  of  scientists
and  Star  Wars  fans.  I'm  very  grateful  for  the  help  they  provided,
brainstorming  ideas,  serving  as  sounding  boards,  contributing   expert
knowledge, and offering valuable feedback: Tom Thatcher, Dr. Charles  Lurio,
Dr. Michael Burns, Dr. Stuart Penn, Dr. John Schilling, Dr.  Korey  Moeller,
Elizabeth Bartosz, Dr. Stephanie Ross, Dr. Andrew Michael , Megan Gentry, M.
Mitchell Marmel, Dr. Paul Viscuso,  Reed  Riddle,  Carrie  Vaughn,  Patricia
Jackson, John Donigan,  Dr.  Michael  Harper,  Janis  Cortese,  Dr.  Michael
Blumlein, Joellyn Crowley , Dr. David Loffredo, Beth  and  Ben  Dibble,  Jay
Denebeim, Bruce Goatly, Dr. Gail Dolbear, Dr. Gary Day, K. Waldo Ricke,  Dr.
Dennis C. Hwang, Bill Hartman, Patrick Randall, and Margo Cavelos. Thanks to
Sue Gagnon, Mark Purington, and the  rest  of  the  staff  at  Saint  Anselm
College's Geisel Library, who went to incredible lengths to get  me  massive
amounts of materials in a timely manner,  and  bravely  fought  off  overdue
notices. Thanks to my editor, Joe Veltre, for his wisdom  and  enthusiasm  ,
and to my agent, Lori  Perkins,  for  all  her  support.  Thanks  to  George
Lucasfor creating this rich, wonderful universe to explore. And on the  home
front, thanks to Igmoe, my iguana, for providing exciting work breaks as  he
chased me around the house trying to mate with me. And to my husband, thanks
for understanding when I only left my computer to eat and sleep (and to  run
from Igmoe), and for living withall the disorder my work generated.  With  a
little water, my office could look just like the  inside  of  a  Death  Star
garbage masher.

     Planetary Environments

     Sir, it's quite possible this asteroid is not entirely stable. 
     -C-3PO, The Empire Strikes Back

     It comes into view as a small, pale dot against the blackness of space.
Dim, inconsequential beside the brilliance of a star. Yet for us,  it  is  a
safe haven in the endless vacuum of space. Only here, on this fragile bit of
rock or others like it, can life develop and survive. It formed billions  of
years ago, the right elements combining in  the  right  proportions  at  the
right distance from its sun to bring it to dynamic life. Volcanoes  breathed
out an atmosphere . Life-giving rains fell, the bit of rock evolved.  As  it
grows closer, the dot gains color and definition.

     Major features are revealed:  rock,  water,  ice,  clouds.  Within  the
atmosphere ,  that  protective,  nurturing  envelope,  more  details  become
apparent. Only on the surface, though, does  the  unique  character  of  the
planet become clear: the shapes and colors of the topography , the  peculiar
quality  of  the  star's  light  scattered  through  the   atmosphere,   the
composition and scents of the air, the strength of the gravity, the  texture
of the ground beneath our feet, the bizarre  life  forms  that  are  another
expression of the growth and development of the planet.

     We have visited many such balls of life-giving elements. Each landscape
is committed to memory.

     A flat plain of sand broken only by harsh, jagged rocks.

     A vast, snow-covered waste. A fog-shrouded swamp chattering with life.

     An ancient forest stretching high into the sky. A planet-sized city  of
level upon level.

     Some seem mysterious; others feel almost like home. We've seen  planets
and moons; we've even traveled through an asteroid field.  Each  has  unique
characteristics. Anakin's and Luke's home world,  Tatooine,  is  part  of  a
binary star system. Naboo has a bizarre internal structure.  The  Ewok  moon
circles the gas giant Endor. In Star Wars, we're swept  up  in  events  that
take us to a wide array of strange and intriguing planets. They  present  an
exciting picture of the universe as we'd like it to be: filled  with  exotic
yet welcoming worlds.

     These planets are generally friendly to human  life-which  is  why  the
human characters have traveled to  them.  In  addition,  though,  they  have
indigenous life of their own, in a  variety  that  keeps  us  surprised  and
delighted. But how realistic is this view of the universe, based on what  we
know today?

     Are Earth- type planets like those we see in Star Wars likely to exist?
And will so many of them be home to alien life?



     YOU CAN'T HAVE AN EMPIRE WITHOUT REAL ESTATE


     To have a universe like that in Star Wars, the first thing we  need  is
planets, and lots of them. If our solar system is a fluke, and we happen  to
orbit the only sun in the universe that has planets,  then  we'll  never  be
able to pop across the galaxy for some Jedi training, set up a  hidden  base
in another solar system, or get into bar fights with intelligent alien life.

     How numerous are planets in our  universe?  Let's  first  look  at  how
planets form, and what ingredients are necessary in  their  formation  .  To
form rocky planets like Earth, we need heavy  elements  like  iron,  carbon,
nitrogen, and  oxygen.  Unfortunately,  they  are  rare.  The  two  lightest
elements, hydrogen and helium, currently comprise 99.8 percent of the  atoms
in the universe. Hydrogen and helium are great for making stars, but not for
creating Earthlike planets or complex life-forms. The heavier  elements  did
not even exist at the beginning of the universe, so stars  formed  in  those
early days could not have Earthlike planets orbiting them.

     Since  then,  however,  stars  have  been  steadily  producing  heavier
elements through the nuclear fusion reactions  that  power  their  brilliant
light. In fusion, energy is produced when lighter elements are  combined  to
make heavier ones. When a star exhausts its fuel and dies, it releases these
heavy elements into space by exploding or by ejecting its outer layers.

     A supernova explosion, through its incredible energy, creates even more
heavy elements. If the star lives in a massive enough galaxy, like our Milky
Way, then these new heavy elements are held within the  galaxy  by  gravity.
They combine with other debris into  a  cloud  of  gas  and  dust,  and  may
eventually form into new stars and planets. These  new,  younger  stars  can
potentially have Earthlike planets, since the heavy elements necessary  have
been thoughtfully provided by the older generation.  Considering  that  Star
Wars is set "a long time ago," is it too long ago  to  allow  for  Earthlike
planets?

     While the universe formed about fifteen billion years  ago,  it  wasn't
until ten billion years ago that enough heavy elements had been  created  to
form a planet like Earth. Dr. Bruce Jakosky, professor of geology at the Lab
for Atmospheric and Space Physics at the University of Colorado at  Boulder,
concludes that " 'A long time ago' is fine if we're talking  a  few  billion
years, but a dozen billion years-that's too long ago."

     So we've narrowed things down  ...  a  bit.  Once  we  have  the  heavy
elements required as raw  materials,  how  do  the  planets  actually  form?
According to current theory, this debris forms a rotating cloud. Just  as  a
ball of pizza dough, when you toss and spin it, will  flatten  into  a  thin
crust, so the rotating cloud will collapse into a  thin,  spinning  disk  of
material. This disk is made up of  gas,  dust,  and  frozen  chemicals.  The
dense, inner section of the disk coalesces first into a star.

     At this point the disk looks like a rotating Frisbee with a hole in the
center, the star in the middle of the hole. Dr.  Jakosky  notes  that  these
disks that form the birthplace of planets seem fairly common.

     "Between one-quarter and one-half of all stars, when they form, seem to
leave behind these disks."

     The solid particles in the disk stick together to form large grains  of
dust. These grains collide  ,  pith  each  other  and  form  larger  grains,
eventually growing into small bodies called planetesimals.

     A planetesimal may be only a few inches across, or it may be  the  size
of the Moon. Some planetesimals remain small, becoming asteroids or  comets.
Others, though, as they rotate around the sun, continue to collide and merge
with each other, in a sense sweeping up all the material at the same orbital
distance from the sun. As a planetesimal collects all the material in a band
around the sun, it becomes a planet. The closer the band is to the star, the
smaller the band's circumference is, and so the less material  there  is  to
create a planet.

     That's why, so the theory goes, smaller planets tend to form closer  to
stars and larger planets farther away. In addition to affecting planet size,
the distance from the star also affects planetary composition. Closer to the
star,  the  disk  is  very  hot,  and  only  materials  with  high   melting
temperatures, like iron and rock, are solid. Thus those elements make up the
majority of the planetesimals, and the planets. In our own solar system, the
four planets closest to the sun-Mercury, Venus, Earth, and Mars-are made  up
mainly of dense rock and iron. Farther from the sun, where  the  temperature
is lower, additional materials  solidify  ,  such  as  water,  methane,  and
ammonia, and become part of the core of the outer planets.

     These larger  planets  have  stronger  gravitational  fields,  and  can
attract huge amounts of light gases, such as  hydrogen,  to  surround  their
cores as massive atmospheres. This process creates distant gas  giants  like
Jupiter and Saturn. Jupiter , for example, has a core ten times the mass  of
Earth,  which  is  impressive,  but  including  its  thick   hydrogen-helium
atmosphere, Jupiter's mass totals 318 times Earth's. Each planet, then, is a
product of the unique conditions of its formation. If this theory  is  true,
then planetary formation is a natural part of stellar formation,  and  there
should be a lot of planets out there. Our current theory  certainly  does  a
fairly good job of explaining the features  we  observe  in  our  own  solar
system.

     But until recently , we've had  no  other  solar  systems  to  test  it
against. In the last eight years,  however,  a  string  of  discoveries  has
thrown the theory of planetary  formation  into  doubt.  Planets  seem  more
common than ever, which supports our theory.  Yet  the  planets  we've  been
discovering around other stars are quite  different  than  those  our  local
system led us to expect.

     Dr.  Jakosky  explains,  "A  lot  of  the  planets  we're  finding  are
oddballs."

     In an attempt to explain the  presence  of  these  oddballs,  many  new
theories are being suggested. While most still start with a disk of material
orbiting a forming star, many suggest  ways  in  which  solar  systems  much
different than our own might result. Why? Because  what  we're  learning  is
that the universe is a much stranger and more varied place than we imagined.



     A PLANET A DAY KEEPS THE EMPIRE AWAY


     While science fiction has long posited the existence of other planets ,
up until recently, we could  only  guess  whether  there  might  be  planets
orbiting other stars in the universe. False  reports  of  the  discovery  of
planets outside our solar system, called extra-solar  planets,  have  arisen
since the 1940s, but only recently have we obtained convincing evidence that
such planets do indeed exist.

     Planets are very difficult to detect because they're much smaller  than
stars and they shine only by catching and  reflecting  a  small  portion  of
their star's light. Our sun, for example, is one billion times brighter than
the planets that orbit it. If we look at a star  through  a  telescope,  the
light from the star completely overwhelms  that  from  any  planets.  As  an
example of how hard it is to find planets, consider that it  took  us  until
1930 to find Pluto, a planet in our very own solar system.

     The nearest star, Proxima Centauri, is ten thousand times farther  away
from us than Pluto.  These  great  distances  make  seeing  planets  through
telescopes nearly impossible.  Instead  of  trying  to  see  and  photograph
extra-solar planets, astronomers instead look for indirect  signs  of  their
presence. A wobble in the normally straight path of a star  could  reveal  a
star being tugged gravitationally back and forth as a planet orbits  it.  We
usually think of a planet circling about a stationary star. But the truth is
both the planet and the star move, orbiting around their center of gravity.

     Imagine two children of approximately equal weight-say the  twins  Luke
and Leia at age seven. They face each other, hold each  other's  hands,  and
begin to spin around. Since they are of equal mass, their center of  gravity
will be the point exactly halfway between them, and they  will  each  circle
around that point. Their footsteps will trace out a  common  circle  with  a
common diameter. Now imagine daddy Vader arrives on the scene. He breaks  up
the circle, turns Luke around to face him, takes Luke's hands  in  his,  and
they begin to spin around. Since Vader is much more massive than  Luke,  the
center of gravity will be much closer to Vader.

     While Vader will not exactly pivot on a single point, he will move  off
that point by only a small amount, his footsteps tracing  out  a  circle  of
tiny diameter, while Luke is whipped around in a wide circle. Just as  Vader
is not entirely stationary, a star is not completely stationary as a  planet
orbits it. The planet's gravity affects the star the  same  way  the  star's
gravity affects the planet.

     Thus the star will move in a small, cyclical  orbit.  Our  sun's  small
orbit is generated mainly by Jupiter, its most massive planet. Since Jupiter
is one-thousandth the mass of the sun, the sun's orbit is one-thousandth the
size of Jupiter's orbit. The sun revolves around a center  of  gravity  just
beyond its surface. Such movements of stars are quite  small,  so  they  are
very difficult to detect. Yet observing stars has  one  important  advantage
over observing planets: stars radiate light  that  allows  us  to  see  them
easily. That's why astronomers are  searching  for  planets  by  looking  at
stars.

     Astronomers have focused on two main  techniques  for  detecting  these
cyclical movements in a star's course. One is  to  visually  look  for  tiny
wobbles back and forth and measure the extent of these wobbles. This is very
difficult, since the wobbles are very small. Let's say the star is the  size
of our sun and is ten light-years away, and the planet orbiting  it  is  the
size of Jupiter. How small would the star's wobble be? Imagine Princess Leia
standing two miles away across the flat desert of  Tatooine.  She  plucks  a
hair out of one of her buns and holds it up.

     The width of her hair, as it appears from two miles away, is  the  size
of the wobble we're looking for. Not surprisingly, a  number  of  scientists
have reported discoveries of planets only to later learn  the  tiny  wobbles
they detected were simply observational errors. A more successful  technique
has been to search for a cyclical Doppler shift in the light coming  from  a
star. Instead of looking for a wobble back and forth  across  our  field  of
vision, scientists study the light from a star to see if it is moving toward
us and away from us in a cyclical manner. This type  of  movement  causes  a
shift in the frequency of light coming from the star.

     Most of us have experienced Doppler shifts-not in light waves,  but  in
sound waves. Imagine a train coming toward you and blowing its whistle in  a
long, sustained blast. Sound waves will propagate out from  the  whistle  in
all directions. Those  waves  coming  toward  you,  traveling  in  the  same
direction as the train, are crunched together by the movement of  the  train
and its whistle. This crunching-up process increases the  frequency  of  the
sound waves, making the tone of the whistle  sound  higher.  The  train  now
passes you and starts moving away, still  blowing  its  whistle.  The  sound
waves coming toward you are now traveling in planet.

     Since we know that the closer a planet is to  a  star,  the  faster  it
orbits, we know that this planet is very close to 51 Pegasi.  In  our  solar
system, the planet closest to the sun, with the shortest orbital  period  or
year, is Mercury. Yet Mercury's year is  a  leisurely  88  days.  The  newly
discovered planet orbits at only one-eighth the distance from Mercury to the
sun. This close, the star would  heat  the  planet  to  a  blistering  1,900
degrees. Not very friendly for life.

     From our theory of planetary formation, we would  expect  a  planet  so
close to its star to be small and rocky. Yet the 51 Pegasi planet is a  huge
gas giant, half the size of Jupiter. We've now confirmed the discoveries  of
about fifteen planets around other stars. Most of  these  are  more  massive
than Jupiter, and most orbit their stars more closely than Mercury.

     Remember, one reason  we've  found  these  "oddball"  planets  is  that
they're the easiest to detect.  Yet  their  existence  calls  into  question
whether our own solar system is the exception or the rule, and  how  planets
really form. Scientists are struggling to understand how these  massive  gas
giants could have formed so close to their stars,  or  could  have  migrated
there after  their  formation.  Not  all  the  planets  we've  detected  are
oddballs, though. We have also discovered Jupiter-sized planets farther away
from their stars, at  an  orbital  distance  comparable  to  Jupiter,  which
suggests to some astronomers that Earthlike planets may also exist in  these
systems. Although we can't yet detect  Earth-sized  planets  around  sunlike
stars, scientists believe they too  may  be  common.  This  makes  the  many
Earthlike planets we see in Star Wars seem fairly reasonable.

     Even with our limited ability to find planets, about one out  of  every
twenty stars we've studied thus far has a planet we can detect .  Scientists
now estimate that perhaps 10 percent of all stars have planets.  That  would
mean our galaxy alone would be home to twenty billion solar systems. As  for
how many planets might be Earthlike, we can only make a very rough estimate.
But scientists now believe perhaps two billion of these  solar  systems  may
have Earthlike planets.

     Earthlike, though, doesn't mean that a planet will look  like  northern
California. It means only that a planet will have a  rocky  composition  and
size similar to Earth. Other than that, it may have very  little  in  common
with our planet. Mercury, Venus, and Mars are considered Earthlike, but that
doesn't mean alien life exists on those planets, or that  human  life  could
survive there.

     Now that we know planets are plentiful, we need three more  ingredients
to create the Star Wars universe. First, planets that can give rise to their
own life. Second, planets that, having the potential to give rise  to  life,
do so. Third, planets that can  support  human  life.  What  qualities  must
planets have to fulfill these needs? Let's consider our first need first.



     TWIN SUNS


     Luke Skywalker stares off across the Tatooine desert  at  the  dramatic
sunset . Two suns close  beside  each  other,  make  their  way  toward  the
horizon. Binary star systems, in which  two  stars  orbit  around  a  common
center of gravity, are fairly common. Yet scientists  think  planets  around
binaries are unlikely, because the gravity of one star may  prevent  planets
from developing around the other. As two stars  of  different  masses  orbit
about each other, the surrounding gravitational field would  shift,  setting
up potential instabilities in the orbits of any planets. Even stable  orbits
would most likely have  complex  trajectories  and  variable  climates.  For
example, as a planet  orbits  past  the  larger,  hotter  star,  the  strong
gravitational field would draw the planet  close,  initiating  a  period  of
searing heat. Then as the planet approaches the smaller,  cooler  star,  the
weaker gravitational field would allow the planet to swing out  to  a  great
distance, sending the planet into a long period of frigid temperatures.

     In addition, such a planet could have  a  complex,  shifting  cycle  of
sunrise and sunset. This would add to climatic instability. But  astronomers
do envision two possible situations in which planets might  form  in  binary
star systems, and might even support life. If the two  stars  are  very  for
from each other-for example billions of miles apart-then  planets  might  be
able to orbit one of the stars with minimal influence from the other.

     For example, Proxima Centauri, the star closest to our sun, is part  of
a trinary star system. Proxima is one trillion miles from its  two  sisters,
though, 250 times the distance from  the  Sun  to  Pluto.  Many  astronomers
believe Proxima could have planets of its own, only  minimally  affected  by
its far-off sisters. From the surface of  one  of  these  planets,  the  two
sisters would appear only as bright stars in the sky. The other  possibility
is that the two stars could be so close together-only a  few  million  miles
apart-that to a planet orbiting for enough away, the gravitational field  of
the two stars would seem almost like that of one.

     Dr. Jakosky estimates, "If the  distance  between  the  stars  is  only
one-tenth the distance to the planet, that would probably be stable."

     In this situation, the orbit of the planet might be close to  circular,
and the temperature might remain relatively stable. At dawn two  suns  would
rise, and at dusk two suns would set, just as  we  see  on  Tatooine.  Thus,
while planets in binary star systems may be rare, Tatooine seems  to  be  an
example of one specific situation in which a planet can have a stable orbit.
Such planets may well exist, and may even support  life.  And  they'll  have
some pretty spectacular sunrises too.



     ARE STAR SYSTEMS SLIPPING THROUGH YOUR FINGERS?


     "A galaxy far, far away" teems with life. On every planet,  over  every
snowbank, hidden in every cave, submerged  in  every  garbage  masher,  life
abounds. This is one of the qualities that makes Star Wars seem so real  and
so fully imagined. But how common is life in the universe? In a few thousand
years, might our descendents be walking into a  cantina  populated  with  an
incredibly bizarre range of life-forms, a real-life "wretched hive  of  scum
and villainy "? Scientists believe  a  wide  variety  of  factors  affect  a
planet's ability to develop life.

     Many of the necessary characteristics depend not on the planet  itself,
but on conditions within its solar system,  and  on  the  planet's  position
within that solar system. Here are a few of the key factors.

     First, a planet must be at the right distance from its star, where  the
star heats it to a temperature neither too hot nor too cold, allowing  water
to exist in liquid form. Planets within a certain narrow range of  distances
from a star will fall into this favorable band, called the  habitable  zone.
Within this zone, a planet  can  potentially  support  life.  In  our  solar
system, this zone begins a bit outside the orbit of Venus and continues past
Earth to the orbit of Mars. So a planet at Mars's location could potentially
harbor life. Yet many factors beside distance from  the  sun  determine  the
surface temperature of a planet. This means sometimes a planet  outside  the
habitable zone may allow life, and sometimes one within the  zone  may  not.
Unfortunately, Mars's small mass-only one- tenth that of Earth-allows it  to
hold only a thin atmosphere, which keeps Mars cold and prevents liquid water
from remaining on its surface. Yet liquid water-and life-may exist below the
surface of Mars. We'll discuss this scenario later.

     Second, a planet must have time to develop life,  particularly  complex
life. During the prime of its life, the more massive a star is,  the  faster
it burns its hydrogen fuel. Our sun is five billion years old, and if  we're
lucky it has another three or four billion years in it-time for George Lucas
to finish that legendary third trilogy of Star Wars movies. High-mass stars,
over ten times more massive than our sun, can burn out in only  ten  to  one
hundred million years. While some basic life might  possibly  have  time  to
form, stars with these short life spans most likely won't give their planets
time to develop sophisticated life.

     Dr. Jakosky believes "it's very plausible that life on Earth  developed
within one hundred million years of conditions allowing  it.  So  you  could
have life develop in these systems. But there's not time for anything beyond
simple single-celled organisms to develop."

     How long do we need for complex life to evolve? It  took  four  billion
years for intelligent life to form on Earth. While large hot stars  are  not
good candidates for life, stars that are too  dim  and  cool  are  not  good
candidates either. Most planets would be too far to receive sufficient heat.
And if a planet was close enough to the star  to  be  within  its  habitable
zone, it would face dangerous tidal forces. Tidal forces become a factor  in
very strong gravitational fields. Since gravitational  attraction  increases
as distances  decrease,  a  planet  in  close  orbit  feels  a  very  strong
gravitational attraction to the star. In fact, in such an intense field, the
gravitational pull on the near side of the planet is significantly  stronger
than the pull on the far side.

     If this difference is too great,  it  will  rip  any  potential  planet
apart, creating a ring of asteroids. If it's  not  quite  that  severe,  the
difference actually creates a braking force on the  planet's  rotation.  The
star literally holds on to the near side of the planet and doesn't  want  it
to rotate away. Thus the planet rotates more and more  slowly,  its  day-the
amount of time it takes to rotate once about  its  axis-growing  longer  and
longer, until ultimately it rotates only enough to keep the same side of the
planet facing the sun forever.

     This means that the planet 's day has now become exactly one year long.
Although the planet turns, then, for those on the side facing the sun, there
is no night. And for those on the side away  from  the  sun,  it  is  always
night. Our own moon, in its close orbit around Earth, has succumbed to tidal
forces, keeping the same face to us always. A planet that has been braked by
tidal forces will be unfriendly to life, with one side  extremely  hot,  and
the other extremely cold. Temperature can be affected by  other  factors  as
well. If a planet 's orbit is too eccentric, or elliptical, it will  undergo
dramatic temperature shifts as it moves closer and farther from the  sun.  A
change in the planet's tilt can also cause climatic changes.

     French  astronomer  Jacques  Laskar  theorizes  that  the  moon   helps
stabilize the Earth's tilt. The  Earth's  axis  is  the  line  we  can  draw
straight through the center of the planet connecting  the  north  and  south
poles. The Earth rotates around this line, giving us day and night.  At  the
same time, it orbits around the sun. Yet the Earth's  axis  does  not  stand
straight up and down, at right angles to the  plane  of  the  solar  system.
Instead, it tilts an average of about  23  degrees.  This  tilt  brings  the
northern hemisphere closer to the sun in the summer, and  takes  it  farther
from the sun in the winter. This allows moderate  changes  in  climate  that
create the seasons. The tilt of the axis isn't quite  constant,  though.  It
varies slightly, oscillating from 22 degrees to 24.6 degrees and back  again
every 41,000 years. This small oscillation is believed  to  be  one  of  the
causes of Earth's ice ages.

     Without the Moon, Dr. Laskar estimates  that  the  Earth's  axial  tilt
would vary from O to 85 degrees. This would create huge climatic changes.  A
tilt greater than 54 degrees would make the poles hotter than  the  equator.
Such an erratic climate would make  it  much  more  difficult  for  life  to
develop, and for any life  to  survive  long  enough  to  evolve  into  more
sophisticated forms. Planets not lucky enough to  have  moons  might  suffer
from this  instability.  Another  danger  to  the  development  of  life  is
meteoroid collisions .

     Meteoroids are  chunks  of  matter  in  space  that  enter  a  planet's
atmosphere. Meteoroids can be tiny specks of dust one-ten thousandth  of  an
inch across or huge chunks miles in diameter. They arise from a  variety  of
sources. But most of the meteoroids that fall to Earth are  bits  of  debris
from the asteroid belt, a belt of small, rocky bodies that orbits in a  zone
between Mars and Jupiter.

     Occasionally these asteroids collide with each  other  at  over  10,000
miles per hour, creating fragments that are propelled toward Earth's  orbit.
Some meteoroids also arise from the Oort Cloud, a zone of comets that orbits
our sun in an  extremely  eccentric  path  that  takes  it  as  far  as  two
light-years away.

     Dr. George Wetherill, planetary scientist at the  Carnegie  Institution
of Washington, theorizes that the strong gravitational fields of Jupiter and
Saturn may have scattered trillions of comets and other  meteoroids  out  of
our solar system. If that is  so,  then  those  planets  act  as  guardians,
sparing Earth from many destructive collisions  .  The  presence  of  bigger
planets in a solar system, then, may be necessary for  life  to  develop  on
smaller planets. Dr. Wetherill estimates that Earth might have suffered  one
thousand times more collisions if Jupiter and Saturn were not in  our  solar
system. Although small impacts might not  have  much  effect  on  us,  large
impacts  can  have  huge  effects  on  a  planet.  Scientists  believe  that
sixty-five million years ago, the impact of an object six miles  across  led
to the death of the dinosaurs.

     Without Jupiter and Saturn protecting us, Dr.  Jakosky  estimates  that
Earth might undergo a huge impact like this not every fifty to  one  hundred
million years, but every ten thousand years. "It's hard to imagine how  life
could survive that extreme an onslaught."

     While many of these theories remain  speculative,  it's  clear  that  a
special combination of characteristics are necessary for a solar  system  to
provide an environment friendly to the formation and development of life. We
can only assume that the star  systems  of  the  life-generating  Star  Wars
planets-Tatooine, Hoth, Dagobah, and others-have these characteristics.

     Is that likely? Of the two billion Earthlike planets scientists believe
may exist in our galaxy, they estimate 2.5  million  may  be  in  "friendly"
solar systems that offer potential long-term habitability.  So  the  planets
we've seen in the movies could easily be in such systems . And if "a  galaxy
far, far away" contains 2.5 million of these "friendly" systems, we may have
a lot more alien species to meet.

     Before you start celebrating, imagining 2.5 million planets with  alien
life, remember that so far we've only discussed  the  conditions  the  solar
system may need to have for one of its planets to support life. Now we  must
consider what qualities the planet itself must have.



     IS THAT A METEOROID IN THE SKY, OR IS THE EMPIRE JUST  TRYING  TO  FIND
ME?


     In The Empire Strikes Back, the rebels establish  a  base  on  the  icy
world of Hoth. Hoth not only supports the human rebels; it supports its  own
indige- nous life-the Tauntauns, Wampa  ice  creatures,  and  others-despite
frigid temperatures and heavy meteoroid bombardment. We'll talk  about  life
in icy environments later. For now, let's consider why Hoth might have  such
heavy meteoroid activity, and what effect this might have on life.

     Hoth is constantly bombarded by meteoroids, which fall  so  often  that
Luke at first mistakes an Imperial probe for one. We discussed  earlier  the
dangers of meteoroid activity, and the role that Jupiter and Saturn may play
in sheltering us from meteoroids. Even with  that  shelter,  it's  estimated
that 8,700 tons of meteoritic matter fall to  Earth  each  day.  Yet  that's
spread over such a huge area, and usually falls in such tiny grains of dust,
that we're not even aware of it. For the rebels to notice and comment on the
high meteoroid activity, Hoth must have significantly greater activity  than
Earth-where we don't notice it at all-and the meteoroids must on average  be
larger than those that fall to Earth.

     In general, scientists believe the younger the  planetary  system,  the
more impacts will occur. If our theory of planetary formation is correct,  a
young system will have many chunks of rock and ice  that  haven't  yet  been
captured by planets. The older the system is, the more these bits will  have
been swept up, either colliding with and being absorbed by planets, or being
thrown out of the solar system by gravitational forces. If we then  theorize
that the Hoth system is young, however, we run into a couple of  big,  hairy
problems: specifically, the Tauntaun  and  the  Wampa  ice  creature.  These
species have evolved on the planet, along with other life-  forms  we  don't
see. To develop such complex life-forms, Hoth must be pretty  old,  probably
several billion years.

     So a young system is unlikely. If Hoth is a mature planet in  a  mature
system, then why does it have such heavy meteoroid  activity?  We  have  two
possible explanations. First, we know that Jupiter and  Saturn  may  shelter
Earth from meteoroid impacts. If the Hoth system doesn't have such  planets,
the rate of impacts could potentially be one  thousand  times  greater  than
Earth's.

     George Lucas provides a second possible  explanation  in  the  asteroid
belt that orbits Hoth's sun. These are the  some  asteroids  that  Han  Solo
navigates through in a hair-raising attempt to evade Imperial pursuit. As we
discussed earlier, the  majority  of  Earth's  meteoroids  are  debris  from
collisions in our asteroid belt. So  perhaps  debris  from  Hoth's  asteroid
field similarly provides Hoth's meteoroids. What might Hoth's asteroid  belt
be like?

     Luckily, we have a sample in our own solar system, a belt  of  millions
of asteroids that revolves around the sun in a region between the orbits  of
Mars and Jupiter. Of these millions, fewer than  ten  are  larger  than  200
miles across, the size of small moons. A larger number, about 250, are  over
60 miles across. Most are 1/2  mile  or  less  across.  While  I  think  the
asteroids in the movie tend to  be  a  bit  bigger  than  this  distribution
suggests, they aren't dramatically different in size from ours. In  our  own
asteroid field, larger asteroids have compacted themselves into the shape of
spheres due  to  gravitational  attraction,  while  smaller  asteroids  have
irregular shapes.

     This too is consistent with Hoth's asteroid field. The  large  asteroid
Han lands in is spherical, while smaller ones are in a  variety  of  shapes.
Each asteroid in our own belt rotates, spinning about an axis  just  as  the
Earth does. Scientists have measured the rotational  period  for  over  four
hundred asteroids. They range from 2.3 hours to 48 days,  with  the  average
time for a single rotation being 10 hours.

     Generally, the smaller the asteroid, the longer the rotational  period,
since these fragments have lost more energy  through  collisions.  The  Hoth
asteroids are spinning much more quickly, many  of  them  having  rotational
periods of only 5 to 15 seconds. And the small ones  sometimes  seem  to  be
rotating faster than the large ones. Since we  have  not  yet  observed  any
asteroid with a rotational period less than 2.3  hours,  scientists  believe
that any asteroid spinning  faster  than  this  would  be  ripped  apart  by
centripetal forces.  Perhaps,  then,  Hoth's  asteroids  are  made  of  some
stronger material.

     Even though there are millions of asteroids in our  belt,  they  rarely
come within half a million miles  of  each  other.  That's  because  they're
spread over such a large area, 6 billion trillion cubic miles.  On  average,
we'll find only one asteroid in a volume of 100 trillion cubic miles. So  it
wouldn't be much of a challenge to navigate our  asteroid  field.  In  fact,
several of our spacecraft have passed through it with no harm. The  asteroid
field Han Solo flies through clearly has many  more  objects,  packed  much,
much more closely together.

     Even in our sparse asteroid belt, collisions do occur. These collisions
are infrequent, yet the asteroids  have  had  over  four  billion  years  to
collide with each other, so many have undergone multiple collisions,  as  we
can tell from the impact craters on them. In the early  days  of  the  solar
system, asteroids were just some of the many planetesimals orbiting the sun.
Some of the asteroids softly collided and  stuck  together,  forming  larger
objects, just as planetesimals grew to form planets. Yet scientists  believe
their process of accretion was disrupted by the nearby formation of Jupiter.
Its strong gravitational field perturbed the orbits of the asteroids.

     While most of them had been in similar, circular orbits, many now  were
drawn into more elliptical orbits, so that rather than bumping  gently  into
each other and sticking together , they now  smashed  forcefully  into  each
other at 10,000 miles per hour, breaking each  other  into  bits.  Thus  the
asteroids never formed into a planet. The asteroids we currently observe are
pieces of larger asteroids  that  have  been  broken  up,  and  the  process
continues, the asteroids grinding each other ever smaller. We might theorize
that some similar gravitational forces are at  work  in  the  Hoth  asteroid
field as well, since those asteroids also failed to coalesce into a planet.

     Yet the extremely high density of  asteroids  doesn't  seem  compatible
with the fairly large-sized objects we see. If they were as close  as  Han's
death-defying asteroid run suggests, they  would  have  collided  with  each
other many, many times over, their grinding down  process  much  accelerated
from that  occurring  in  our  own  asteroid  field.  We  have  evidence  of
collisions among Hoth asteroids, in the impact craters on the  potato-shaped
asteroid and the large circular asteroid Han lands  on.  If  Hoth  asteroids
collide with velocities similar to those of our asteroids-and some  of  them
seem pretty speedy-then it seems as if they would all be reduced  to  rubble
very quickly. Dr.

     Charles Lurio, aerospace engineering consultant, estimates, "They'd  be
sand-sized rubble probably in a lot less than one hundred years."

     To maintain itself over billions of years, the asteroid belt would have
to have much less frequent collisions, like our own, or  it  would  need  to
balance destructive high-speed collisions with constructive soft collisions.
Perhaps conditions in the Hoth asteroid  field  somehow  allow  this  latter
alternative. If debris from Hoth's  asteroid  field  is  raining  down  with
relatively high frequency on Hoth, would all these impacts have an effect on
life? Meteoroids 1 mile across or more hit Earth about every 300,000  years.
If meteoroids strike Hoth 1,000 times more often, then such an impact  would
occur every 300 years. A meteoroid this size would explode with the force of
the Earth's entire nuclear arsenal. It would leave a crater 10 miles across,
and scientists believe it would throw so much dust up  into  the  atmosphere
that it would cause major climatic changes, cooling the planet  and  perhaps
even triggering an ice age.

     In fact, this may very well have happened to  Hoth  before  the  rebels
arrived. And if it happens again while they're there, well, the Empire won't
even have to show up to take care of those pesky rebels.



     IS THE UNIVERSE HALF EMPTY OR HALF FULL?


     I have good news and bad news. Here's the bad news.  Even  if  a  solar
system provides a favorable long-term environment for a  planet  to  develop
life, the planet must have numerous specific qualities in order to give rise
to life. Consider the huge number of favorable conditions that  combined  to
allow the development  of  life  on  Earth.  This  conjunction  of  so  many
characteristics must be extremely rare. You might even call the  development
of life on Earth a cosmic fluke.

     What I have just articulated for you is what I call the  "pessimists  '
theory." It dominated scientists' thinking until about ten years ago, and is
still subscribed to by many. Let's explore this pessimists' view,  in  which
the development of life on other planets is even less likely than  surviving
a direct assault on an Imperial star destroyer. Life arose on Earth  due  to
many factors. For life to  arise  on  other  planets,  we  need  these  same
factors.

     Here are just a few. We need a  planet  with  heavy  elements  such  as
carbon and oxygen that are the building blocks of organic molecules  and  so
of complex life. Earth is a treasure trove  of  such  elements.  We  need  a
planet with a moderate speed of rotation, which gives  us  days  and  nights
that are neither too long nor too short. Mercury's  day  is  88  Earth  days
long, as is its night. Such long periods of  heating  and  cooling  lead  to
extremes of temperature, 800 degrees during the day, - 300 degrees at night.

     On the other  hand,  very  rapid  rotation,  which  would  cause  rapid
temperature changes, could generate  violent  weather  patterns  that  would
discourage the formation of life. We need a planet with  a  strong  magnetic
field, which protects us from high-energy charged  particles  in  space.  We
need a planet with enough heat  in  its  early  years-through  gravitational
contraction, meteoroid impacts, and radioactive decay of  elements-to  bring
it to the melting point.  This  is  how  the  Earth  became  separated  into
different regions, such as the crust, mantle,  and  core.  Currents  in  our
molten core  generate  the  Earth's  protective  magnetic  field  and  drive
volcanic action. Volcanic action melts rock, which contains bound within  it
huge amounts of water,  carbon  dioxide,  and  other  chemicals.  These  are
released as gas from the volcanoes, and scientists believe those gases to be
the major source of our atmosphere and oceans.

     We need a planet massive enough to hold an  atmosphere  to  it,  unlike
Mercury or the Moon. An atmosphere offers a second line of  defense  against
high-energy charged particles from space and can  protect  the  planet  from
damaging radiation as well.  The  atmosphere  must  not  contain  a  lot  of
greenhouse gases like carbon dioxide , ozone, or water  vapor,  which  would
make the atmosphere trap too much heat. Such greenhouse gases are what  make
Venus so hot, hotter than Mercury, even though Venus is twice  as  far  from
the sun. The temperature is  critical,  because  scientists  believe  liquid
water is necessary for life. Why is liquid water so critical?

     Dr. Trent Stephens, professor of anatomy and embryology at Idaho  State
University, explains, "In order for atoms or molecules to be  able  to  move
around sufficient distances and sufficiently rapidly for chemical  reactions
to occur, we need a medium for them to move around in.  Solids  don't  allow
them to move rapidly enough. In gases, the atoms  are  so  far  apart,  they
don't collide sufficiently often to be involved in life. A liquid medium  is
necessary. For carbon-based chemical reactions to occur, water is by far the
best liquid."

     Water has a number of unique properties that offer advantages to  life.
Water is the only material that is more dense in liquid form than in  solid,
which makes ice float. Such ice can  form  a  protective  covering  in  cold
environments, prolonging the existence of water below. Almost half the known
elements are soluble in water. This  allows  water  to  serve  as  a  medium
through which nutrients come to an organism and waste products are  removed.
Oxygen dissolved in water allows fish to  breathe.  Nutrients  dissolved  in
water are absorbed by the roots of plants and by the  digestive  systems  of
animals.

     "Water and life go together hand in hand," Dr. Kent  Condie,  professor
of geochemistry at New Mexico Institute  of  Mining  and  Technology,  says.
"You've got to have one for the other."

     Some scientists posit that other liquids might serve in place of water,
such as methane or ammonia. But Dr. Jakosky explains, "Water is so abundant,
since hydrogen and oxygen are abundant, that limiting ourselves to water  is
not terribly limiting. We expect water to be  more  abundant  on  Earth-type
planets than any other liquid material." Not only do we need water,  but  we
need ocean tides. Tidal forces generated by the  nearby  Moon  create  ocean
tides on Earth, which in turn create tidal pools, and a  band  of  shoreline
that is exposed at low tide  and  covered  at  high  tide.  These  may  have
encouraged the formation of life that could survive both in water and on dry
land.

     Dr. Clifford Pickover, biochemist and author of The Science of  Aliens,
believes that without the Moon, "the evolutionary  transition  to  land  may
have  never  taken  place  because  the  water-land   edge   would   be   an
insurmountable barrier. The diversity of life  on  Earth  would  be  reduced
fantastically^and humans would not have evolved."

     I could go on, and many have, writing entire books on all  the  factors
necessary to the  development  of  life.  But  you  get  the  idea.  In  the
pessimists' view, we essentially need to reproduce the  Earth's  environment
with only minor deviations in order to generate  life.  While  this  may  be
necessary to produce Earthlike life, saying it's necessary  to  produce  any
life is making quite an assumption. Yet most of the planets we see  in  Star
Wars do  reproduce  the  Earth's  environment-even  more  closely  than  the
pessimists would say is necessary. It would  seem  extremely  unlikely  that
many planets  would  share  all  these  characteristics.  But  as  we  know,
scientists have estimated there may be 2.5 million  planets  with  size  and
composition similar to Earth and a solar system favorable to life.

     If only a tiny percentage of these come close  to  reproducing  Earth's
environment, that could potentially  provide  the  planets  we  see  in  the
movies. Pessimists would say that tiny percentage is vanishingly  small.  In
fact, many pessimists believe that all these characteristics  came  together
in the entire history of the universe to create life only once: on Earth.

     But the optimists tell a different  story.  Let's  turn,  now,  to  the
"optimists' theory," in which life on other planets not only  seems  likely,
it seems inevitable.



     A HOME AWAY FROM HOME


     Earlier, I mentioned three ingredients necessary for  a  universe  like
that depicted in Star Wars. We've been talking about the first two:  planets
that can and do give rise to alien  life.  In  those  discussions,  the  big
unknown is how wide a range of conditions alien life can survive. The  third
ingredient, though, involves a more familiar  life  form:  humans.  We  need
planets that can support human life. But how wide can  human  life  survive?
The movies show us many planets that seem to be settled by humans. For those
who want to argue that the people we meet in Star Wars are  not  humans  but
some alien species with organs and powers  unfamiliar  to  us,  I  have  two
points to make.

     First, we see no sign of any  characteristics  that  would  distinguish
Star Wars people from humans. They look  and  behave  exactly  like  humans.
Second, they are actually called "humans" in the movies .

     C-3PO's  specialty  is  "human/cyborg  relations,"  and  at  one  point
Threepio says of Luke, "He's quite clever, you know ... for a human being."

     In the Tales of the Jedi comics, we learn that in the days of  the  Old
Republic, much colonizing of the galaxy occurred. Thus we can  imagine  that
the human species originated on a single world, similar to Earth,  and  then
spread to other worlds. Calling Han Solo Corellian,  then,  is  rather  like
calling him French. It tells us where he's from, but  not  what  species  he
belongs to. When we think of colonizing another planet, most of us generally
imagine huge airtight domes within which we would live, sheltered  from  the
unfriendly environment. Yet Star Wars shows humans living on many  different
planets without any isolating domes or breathing devices.

     How can they survive in  these  alien  environments?  There  are  three
options.

     First, colonists could potentially be genetically  engineered  to  cope
with different environments. If such changes were made, though,  then  Luke,
engineered to live on Tatooine, would have  difficulty  surviving  on  Hoth,
which has a much different climate. In addition, we  see  no  sign  of  such
genetic differences. If they did exist, then we  might  think  interbreeding
among residents of different planets would cause problems, and perhaps  even
be impossible . Yet Han and Leia don't seem to consider this a concern.

     Second,  rather  than  altering  the  colonists,  we  might  alter  the
environment . Some scientists believe  we  will  be  able  to  make  planets
habitable  through  terraforming,  transforming  unfriendly   planets   into
Earthlike ones through artificial means. For example, might we  be  able  to
give Mars a life- sustaining atmosphere and liquid water? While  this  would
take huge amounts of energy, we can assume that Star Wars technology,  which
allows rapid interstellar travel, has access to such levels of energy.

     James Oberg, orbital rendezvous specialist for NASA and author  of  New
Earths,  believes  cold  Mars,  with  its  minimal  atmosphere,   might   be
terraformed through several techniques. Since dark-colored material  absorbs
more of the sun's energy than light-colored material, he suggests dark  soot
be spread on  the  planet's  surface.  "If  permafrost  (giant  dust-covered
glaciers) exists, it might melt, flooding the surface after a billion  years
of drought."

     Further heat "could be provided by giant space mirrors, 1,000 km  on  a
side, concentrating sunlight onto  the  planet."  In  addition  to  creating
liquid water, the heat could bring frozen carbon dioxide in the  polar  caps
and soil into a gaseous state. The atmosphere  might  then  thicken  to  the
point where plants could be introduced, setting up an ecosystem friendly  to
man. These ideas remain extremely speculative for now.  In  any  case,  this
doesn't seem to be taking place in Star Wars, at least not  on  the  planets
we've seen so for. For example, if Tatooine were terraformed,  substantially
changing its temperature and atmosphere, the process would likely  kill  off
any indigenous life forms. Yet we are told that the Jawas, Sand People,  and
other species are native to Tatooine.

     We have one other possibility. Colonists might use artificial aids when
initially arriving on the planet but gradually become accustomed to the  new
surroundings. Such adaptations, which occur during a person's lifetime,  are
called acquired character. We're extremely limited in how much we can adapt,
though. We can put on more layers of fat to protect ourselves from the cold;
we can produce more red blood cells to help  us  acclimate  to  the  thinner
atmosphere at high altitudes; we can develop stronger muscles to support  us
if we gain weight. Similarly, those living on a planet that is colder, has a
thinner atmosphere, or heavier gravity could make minor adaptations.

     Over generations, colonists might evolve traits that  would  help  them
cope in this new environment. This process of evolution,  driven  by  random
genetic mutations and survival  of  the  fittest,  has  occurred  throughout
Earth's history,  as  organisms  have  adapted  to  new  homes  or  shifting
climates. While such evolutionary adaptation may have  occurred  in  limited
cases in the very early days  of  the  old  Republic,  when  colonists  were
isolated on a planet for generations, the galaxy we see in the movies  seems
very well traveled, with residents of one  planet  routinely  journeying  to
other planets.

     Since we see  no  sign  of  any  acquired  characters  or  evolutionary
adaptations in any of the humans in the movies, we must  assume  that  these
are minor, meaning these environments are quite similar to the  home  planet
of humans. Thus we're looking for planets  on  which  humans  could  survive
without any special equipment or adaptations.

     How likely are we to find a nice selection of those? Well, they'd  need
all those qualities listed in the previous section and many, many more  just
to allow us to survive. Even more than bare survival, though,  we'd  want  a
planet to offer a comfortable place to live. Scientists have estimated  that
humans wouldn't be comfortable living in temperatures  that  average  higher
than 104 degrees or lower than 14 degrees -which may be why Hoth isn't a big
vacation spot. Gravity over 11/2 times that of Earth would be tiring to live
in. Each action would require more effort, since you would weigh 1 1/2 times
what you currently weigh-as if you'd just sat through The Phantom Menace one
hundred times in a  row,  eating  three  boxes  of  candy  at  each  showing
(actually, that doesn't sound like such a bad idea).

     Gravity too much lower than Earth's would make you lose muscle and bone
mass, leaving you weak and brittle- boned. The  most  difficult  quality  to
obtain may be a suitable atmosphere.

     The idea that another planet's atmosphere might be  breathable  for  us
seems unlikely to Dr.  Jakosky.  "It  doesn't  take  much  to  make  it  not
breathable. The composition of  the  Earth's  atmosphere  is  very  much  an
accident of its history. And it's very unlikely  we'd  find  another  planet
with a similar environment." Dr. Pickover agrees. "This  is  very  unlikely,
given how planetary atmospheres are, and how specifically adapted  creatures
are to the world on which they evolved." Just as each planet is a product of
the unique conditions of its formation and existence, we humans are products
of the planet on which we developed, specifically designed  to  function  in
this particular environment. Finding another setting in which we are equally
at home would be very difficult. These cannot be  planets  that  are  simply
Earthlike; they must almost exactly reproduce  conditions  on  Earth,  which
indeed is what most of the Star Wars planets do.

     As we established in the previous section, a relatively small number of
such planets may exist. Yet we're much more  likely  to  find  planets  that
require some minimal use of technology for humans to survive.  All  of  this
leads to another conclusion. Just as man would have trouble living on worlds
other than the one for which he was designed, so aliens would  have  trouble
living they were designed. Thus the Mos Eisley cantina, in which many aliens
mix and mingle in a single environment, becomes very unlikely. But what good
is a bar, if your face is enclosed in a breathing mask? Perhaps Darth  Vader
knows the answer....



     "THERE ARE MORE THINGS IN HEAVEN AND EARTH"


     While the pessimists' theory was the accepted wisdom for many years, it
now seems that all these conditions may not be required for life. What  many
scientists are coming to believe, based on recent discoveries, is that alien
life may be quite different from  terrestrial  life,  and  may  be  able  to
survive under a much wider range of conditions than previously believed.  In
the last twenty years, scientists have been  shocked  to  discover  life  in
extreme environments on Earth that we had previously  believed  inimical  to
life. We've discovered primitive organisms living over two miles underground
on only water and rock; thriving in boiling water  from  super-hot  volcanic
vents on the ocean's floor; and luxuriating in the frigid Arctic Ocean.

     These bacterialike organisms  are  called  extremophiles  because  they
thrive in extreme environments. Scientists now  believe  that  thousands  of
undiscovered extremophiles exist on Earth. These organisms are  a  lot  more
than curious  oddities.  In  fact,  they  may  have  been  among  the  first
life-forms to develop on Earth. You've probably heard the theory  that  life
on Earth originated in a "chemical soup" with lightning triggering  chemical
reactions. Yet many scientists these days believe life on  Earth  originated
around underwater volcanic vents, called  hydrothermal  vents.  These  vents
shoot out superheated  water  and  minerals,  providing  energy  that  helps
trigger the formation of organic molecules and encourages the growth of more
complex life. Since Earth underwent heavy meteoroid bombardment  during  the
early part of its existence, the Earth would have been much hotter then than
it is now, with conditions like those around hydrothermal vents more  common
.

     Many scientists believe that heat-loving extremophiles  may  have  been
the first life on Earth four billion years ago  and  the  ancestors  of  all
life. The discovery of life in such extreme environments suggests that  life
may also exist in similar extreme conditions on  other  planets.  While  the
surface of Mars seems a dry,  frigid  wasteland,  Dr.  David  McKay,  senior
scientist for planetary exploration at NASA's Johnson Space Center, believes
that conditions about a mile below the surface of Mars may be quite  similar
to those deep underground on  Earth,  with  geothermal  heat  from  volcanic
activity and a groundwater system.

     "Underground on Mars is a  good  place  to  look  for  life."  Possible
evidence that life existed on Mars several hundred  million  years  ago  was
uncovered in 1996. Dr. McKay  and  colleagues  claimed  to  have  discovered
organic molecules and possible fossilized bacteria in  a  Martian  meteorite
found in Antarctica. While the evidence is  still  controversial,  the  rock
contains a combination  of  elements  that  strongly  suggest  life.  "I  am
convinced," Dr. Stephens says, "at least  tentatively,  that  the  meteorite
from Mars really does have evidence of life in it." If life can survive  and
thrive in a wider range of conditions than we thought,  then  we  no  longer
need other planets to reproduce Earthlike conditions in order to  give  rise
to life. In that case, we can reduce the requirements for the development of
life to three: complex organic molecules, water, and energy.

     To be  considered  organic,  a  molecule  need  not  be  created  in  a
biological process; it simply needs to contain carbon, hydrogen, and oxygen.
Dr. Jakosky believes we  needn't  even  require  the  existence  of  organic
molecules, but only of the elements out of which these could be built.  With
this new outlook, we see preliminary indications of life  everywhere.  We've
discovered complex organic molecules on  the  outer  planets  of  our  solar
system, on comets and meteorites, in interstellar dust, and  even  in  other
galaxies.

     "There's carbon galore out there," Dr. Stephens says.  Some  scientists
believe such molecules, carried by extraterrestrial sources, introduced  the
building blocks of life to Earth. Ten percent  of  the  meteoritic  material
landing on Earth is made up of organic molecules, "seeding" the planet  with
the basic ingredients for life. Some meteoroids even carry amino acids,  the
building blocks of proteins. And Earth isn't the only planet receiving these
"seeds."

     Many scientists believe ice-covered Europa, a moon of Jupiter  slightly
smaller than our Moon, may also harbor life. While Europa has  a  very  thin
atmosphere that includes oxygen, the atmosphere doesn't seem  sufficient  to
support life on the frigid surface. Since Europa is far  outside  our  sun's
habitable zone, we used to believe  that  the  planet  was  covered  with  a
150-mile-thick layer of ice.  Yet  data  from  the  Galileo  probe  in  1996
revealed that liquid water may exist beneath a relatively thin layer of ice,
forming an ocean that may be a breeding ground for life. Since  Europa  gets
very little light and heat from the sun, how could liquid water exist?

     Heat from radioactive elements in Europa's core and tidal gravitational
forces caused by  Jupiter  and  Jupiter's  other  moons  most  likely  drive
geological activity and heat the planet, preventing the water from freezing.
Scientists now  theorize  that  Europa's  internal  heat  may  have  created
hydrothermal vents on the ocean floor just as it has on ours, and that these
vents may have stimulated the formation of life, just as we believe they did
on  Earth.  Dr.  John  Delaney,  an  oceanographer  at  the  University   of
Washington, feels sure that life does exist on Europa.

     If life can exist on Europa, imagining life on Hoth is easy. Alien life
may currently exist,  then,  on  two  other  bodies  in  our  solar  system.
Scientists also believe life may have existed  in  the  past  on  additional
bodies, particularly Venus  and  Saturn's  largest  moon,  Titan.  Since  we
believe that life either currently exists or may once have existed  on  four
different planets and moons in our solar system, life in other solar systems
seems fairly likely. Another piece of evidence in support of the  optimists'
theory is that scientists now believe life on Earth formed much earlier than
previously believed, soon after conditions arose that made the existence  of
life possible.

     Around 4 billion years ago, near  the  end  of  the  Earth's  formation
process, the bombardment of Earth by planetesimals finally slowed.  Evidence
now indicates that life may have existed as long as 3.85 billion years  ago,
and that life was widespread by 3.5 billion years ago. This means life  took
only a few hundred million years to form. Dr.  Jakosky  believes  that  this
rapid development  "suggests  that  the  origin  of  life  must  be  a  very
straightforward, natural process. Any  planet  that  has  the  environmental
conditions we think are necessary for life should undergo an origin of life.
It's hard  to  believe  it  wouldn't  be  common  any  place  you  have  the
ingredients. The most likely outcome is  that  life  is  widespread  in  the
universe."

     The optimists even have an answer to  the  pessimists'  view  that  our
solar system, and our Earth, embody a unique combination of  characteristics
that is extremely unlikely to arise again. Why, the optimists  ask,  is  our
particular solar system so unique? We orbit  a  fairly  average  star  in  a
rather unremarkable section of the galaxy. So rather than  saying  that  our
solar system is somehow unique, isn't it more reasonable to say that similar
stars in  similar  neighborhoods  might  similarly  develop  life?  If  life
originated once, the optimists argue, then it probably  originated  multiple
times. And their view is now becoming the dominant one among scientists.

     Dr. Jakosky believes that "life is common,"  and  feels  we're  on  the
verge of a great breakthrough. "It's been just within  the  last  few  years
that we've discovered planets and we've discovered the potential for life to
exist on other planets. That makes this a special time  in  the  history  of
humanity. We're  the  first  generation  that  has  a  realistic  chance  of
discovering life on another planet."

     Dr. Stephens is also hopeful about the existence of alien  life.  "Some
biologists think we're the result of a series of  accidents.  I  think  that
idea is absolutely preposterous. It has led us to believe  our  universe  is
sterile except for this tiny insignificant corner of the universe  where  we
just happened to be lucky. I don't think that's the case at all."  This  new
vision, of a universe filled with life, seems to reflect perfectly the  Star
Wars universe, in which life has developed in every available niche.



     JOURNEY TO THE CENTER OF NABOO


     Naboo is a puzzle. According to the official  Star  Wars  website,  the
planet Nis made up of large rocks thousands  of  miles  in  diameter.  These
rocks don't fit together terribly neatly, creating a honeycomb structure  of
caves throughout the planet's interior.  This  extremely  unusual  structure
defies natural explanation. The most likely explanation, actually,  is  that
the planet was artificially created, either  built  from  scratch  like  the
Death Star or altered through some sort of massive  mining  operations.  But
the description doesn't indicate any artificial components  or  alterations.
Let's consider, then, the factors that would  be  involved  in  the  natural
formation of such a planet. The major difference  between  Naboo  and  other
planets seems to be that the many rocks that comprise it  never  melted  and
fused into a unified planet. Naboo  remains  a  conglomeration  of  separate
rocks, held together by gravity. Since planets are formed by an  aggregation
of planetesimals, it makes sense that Naboo is made up of  many  rocks.  Yet
when planetesimals collide, like asteroids, they will either collide at high
velocities and break each other AY apart, or collide at low  velocities  and
stick together.

     When they stick together, much of the kinetic energy of their motion is
converted into heat energy. This heat fuses  the  bodies  together.  If  the
planetesimals forming Naboo failed to fuse, the  heat  generated  must  have
been minimal, which means the planetesimals  must  have  been  traveling  at
nearly the some velocity in the some  direction  when  they  gently  touched
together. While two small planetesimals might possibly  come  together  like
this, we get in trouble when the proto-Naboo has grown larger. As  the  body
that will eventually become Naboo grows larger, its gravitational attraction
will grow stronger. It will draw planetesimals to it with  increased  force,
and they will accelerate toward it and impact it with higher velocity.

     Heat is an unavoidable consequence. Thus the only way these  rocks  can
come together without generating  significant  heat  is  if  they  all  come
together simultaneously, at very low relative velocities. This would require
some bizarre  gravitational  forces  to  be  herding  1,  the  planetesimals
together, forces that are hard to imagine. If the planet does  somehow  form
in this way, would it remain this way? Most  planets  differentiate  into  a
core and separate layers.  As  we  know,  the  early  Earth  was  heated  by
gravitational  contraction,  meteoroid  impacts,  and   radioactive   decay,
bringing it to the melting point.

     This is how the Earth separated into a core, mantle, and crust. Some of
these heat-generating elements may have been scarcer on  Naboo  than  Earth.
Naboo may have suffered fewer meteoroid impacts than Earth, and it may  have
a smaller fraction of radioactive elements in its rock. This could  possibly
explain why it never reached the melting  point  and  differentiated  .  Yet
Naboo doesn't seem to have particularly light gravity, so we can  assume  it
has a mass similar to Earth's. A planet with the mass of Earth will  feel  a
strong gravitational attraction inward.

     Every rock in that planet will be drawn toward the center, which is why
the planet stays together. And the deeper a rock is beneath the surface, the
greater the downward pressure it feels from all the material above  it,  all
pushing toward the center. This pressure of the outer layers  on  the  inner
ones is what causes large asteroids and planets to contract into a spherical
shape. If a cave within a planet is made of materials that  can't  withstand
this pressure, it will collapse. In the case of Naboo, it seems likely  that
these caves would have collapsed, particularly  those  a  significant  depth
beneath the surface.

     The Naboo rocks must have some special structural strength that  allows
them to withstand the pressure, and that has kept them from contracting  and
melding with one another. The special  structure  of  Naboo  also  makes  it
difficult to understand how it can  have  liquid  water  or  an  atmosphere.
Scientists believe that both  of  these  arose  on  Earth  through  volcanic
processes. Without enough heat to melt the rock and  close  those  gaps,  it
seems unlikely that Naboo would have volcanism. An alternate  theory  posits
that a planet's water might come from comets impacting the surface.  Comets,
often described as "dirty snowballs," carry a fair amount of ice. Yet recent
scientific observations have thrown this theory  into  doubt.  Whatever  the
answer, Naboo must certainly have  arisen  from  a  strange  combination  of
factors. And how a planet so different from Earth might  have  developed  an
environment so similar remains a mystery.



     MOON OVER ENDOR


     Now that we know some of the conditions necessary for life,  let's  see
if those conditions are satisfied in a couple of the places  where  we  find
life in Star Wars. Around the silvery gas giant Endor, nine moons orbit. The
largest of these, the size of a small planet, is home to an  ancient  forest
and a species of diminutive furry creatures called Ewoks. But is  a  moon  a
likely home for the Ewoks? Are moons likely homes for life? If our own solar
system is any indication, moons  are  fairly  common.  Except  for  the  two
planets closest to our sun, Mercury and Venus, all the planets in our  solar
system have moons. We have a total of over sixty.

     Saturn has the most with eighteen. The majority of our  solar  system's
moons are quite small, though-as small as ten miles  across.  These  may  be
asteroids that were scattered out of our asteroid belt  and  gravitationally
captured by the planets.  Such  tiny  moons  are  too  small  to  retain  an
atmosphere or give rise to sophisticated life. Larger moons are less common.
Saturn has only one, Titan. Jupiter has four: lo,  Europa,  Ganymede  ,  and
Callisto. The largest moons-Titan, Ganymede, and Callisto-are actually about
equal in size to Mercury.

     It seems reasonable , then, that the gas giant Endor  has  nine  moons,
and that one of them may be of significant size. In our solar system,  Titan
is the only moon with a thick atmosphere,  so  a  life-giving  atmosphere  ,
while not common, is at least possible. What would  conditions  be  like  on
such a moon? If the Ewok moon was made of the same materials  as  Earth  yet
was the size of Ganymede, it would have  gravity  only  7  percent  that  on
Earth. This would take some getting used to, since if you weighed 150 pounds
on Earth, you'd weigh only 10.5 pounds on Endor's moon.

     Since the gas giant Endor is quite massive, the moon  would  likely  be
subject to tidal forces. Presumably the Ewok moon is not so close  to  Endor
that tidal forces would rip it apart. Yet even so, the forces would slow the
rotation of the moon. As we discussed earlier, tidal forces have braked  the
rotation of our Moon so that it keeps the same side facing the Earth at  all
times. Ganymede similarly presents the same face always to Jupiter. If  this
is also true of Endor, those who live on one side of the moon  would  always
see Endor in the sky, undergoing changes over the course of a day  like  the
phases of the Moon. Those who live on the other side of the moon would never
see Endor.

     Being in this sort of tidal lock is much less serious for a  moon  than
it is for a planet. If a planet is tidally locked about the  sun,  one  side
will bake while the other freezes. In this case, although one  side  of  the
moon always faces Endor, both sides will  receive  sunlight.  The  cycle  of
light and dark will not depend on the rotation of the moon about  its  axis,
but instead on its revolution about Endor. One day on the Ewok moon would be
the time it takes to orbit once around Endor. The  large  moons  of  Jupiter
take from 1.7 to 16.7 Earth days to orbit their planet.

     The farther the moon is from the  planet,  the  longer  its  period  of
revolution. As we discussed, the best chance for complex life  on  the  Ewok
moon occurs if it has a day only a few Earth days long. A longer  day  would
most likely result in  serious  temperature  extremes  and  violent  weather
patterns unfriendly to life. So the Ewoks would be better off  with  a  moon
closer to Endor. Tidal forces could also provide energy potentially  helpful
to life. They would generate internal heat within the moon, as we believe is
happening on Europa. This internal heat could help generate volcanic action.
Volcanoes could then vent water vapor into  the  atmosphere  and  ultimately
lead to the creation of oceans, as we believe happened on Earth.  But  would
the temperature on the planet allow liquid water to form?

     For an Earthlike environment like the one we  see  on  the  Ewok  moon,
Endor would need to orbit within the habitable zone of its  star,  as  Earth
does. This would put any moons into the habitable zone as well. Endor  is  a
gas giant like Jupiter and Saturn, though, and they  orbit  far  beyond  the
habitable zone. But as we know,  in  the  past  few  years  scientists  have
discovered gas giants  orbiting  other  stars  much  more  closely  than  we
believed possible. This suggests that a gas giant within the habitable  zone
is possible. Thus life on such a moon seems quite believable.

     And if gas giants in close orbits are as numerous as  we  now  believe,
life on moons around those gas giants may be more  plentiful  than  life  on
Earthlike planets. Life on the  Ewok  moon  may  not  be  all  cuddling  and
singing, though. One problem the Ewoks would face is radiation. Jupiter  has
lethal radiation belts like Earth's Van Allen belts, only Jupiter's are much
larger and more intense. These radiation belts are  generated  by  Jupiter's
powerful magnetic field, which is about ten times stronger than Earth's. The
magnetic field traps high-energy electrons and  protons  in  space,  causing
them to spiral back and forth at high  velocity  along  the  magnetic  field
lines.

     To picture the magnetic field lines, you might recall an experiment  in
science class, in which you scatter iron filings onto a sheet of  paper  and
then put a bar magnet onto the paper. The filings move to arrange themselves
along the magnetic field lines, which emanate upward out of the  north  pole
of the magnet, bow out around the side of the magnet in  a  semicircle,  and
come together again at the south pole of the magnet. Now  imagine  that  bar
magnet standing upright within the center of  Jupiter.  The  magnetic  field
lines emanate from the north  pole,  bow  out  into  the  space  surrounding
Jupiter, and then come together again at Jupiter's south pole.

     Now imagine charged particles spiraling  rapidly  around  these  lines.
While the magnetic field keeps most of these particles away from the  planet
itself, it's bad news for anything nearby.  When  the  Galileo  space  probe
traveled into  one  of  Jupiter's  radiation  belts,  its  heat  shield  was
penetrated by a million high-energy particles per  second.  The  four  inner
moons of Jupiter travel through Jupiter's radiation belts and are  bombarded
with these particles. Such high-energy particles  can  rip  through  matter,
breaking  apart  molecules  -including  DNA-and  atoms.  Such  radiation  is
extremely harmful to humans and almost all living creatures.

     Dr. Jakosky says, "A terrestrial life form that was transplanted to the
surface of Europa would not be able to survive for very long at all  due  to
the breaking of the chemical bonds." Yet there is an exception to this rule.
Some hardy terrestrial bacteria  can  withstand  extremely  high  levels  of
radiation. In fact, Dr. Jakosky points out, "They live in the  water  inside
of nuclear reactors!" Although they sustain  serious  genetic  damage,  they
have special methods for coping with this damage and rapidly  repairing  it.
If the Ewoks have similar abilities, they might be able to survive  in  such
an environment. I wouldn't hold out much hope for Luke, Vader, and  all  the
nonnatives , though!

     Another  possibility-one  more  friendly  to   tourists-is   that   the
atmosphere of the Ewok moon shields the  surface  from  radiation.  Our  own
atmosphere provides a similar shield. The atmosphere of the Ewok moon  would
have to protect against an even  greater  radiation  threat,  but  it  could
potentially keep its furry little occupants safe. One  further  possibility.
If a ring of rocky material orbits between Endor and the Ewok moon,  it  may
absorb the charged particles , clearing  the  area  beyond.  A  ring  around
Saturn has been shown to reduce the number of charged particles. And a  ring
of space debris around Earth is being found to create a similar effect.  The
key factor in all of this is the distance of the moon from Endor.  The  moon
would need to be close enough to have a short enough day and internal  tidal
heating; yet it would need to be far enough to  prevent  tidal  forces  from
ripping it apart and to keep radiation to a minimum level. The distance from
Endor to the moon can't be too far or too close; as all bears know,  it  has
to be just right.



     THE "BRIGHT CENTER TO THE UNIVERSE"?


     The planet we've had the most time to visit is Tatooine.  It  feels  so
familiar now, I almost feel like I've been there. Home of  Anakin  and  Luke
Skywalker, Tatooine is a harsh planet and appears to have no open bodies  of
water. Violent sandstorms sweep a landscape of desolate  sand  dunes,  sharp
mountains , narrow canyons, and barren rocky wastes. Water apparently exists
beneath the surface of the planet and as water vapor in the  air.  While  we
don't know all the details of Tatooine's environment,  we  do  have  similar
environments on Earth: deserts.

     The defining  characteristic  of  a  desert  is  the  small  amount  of
precipitation it receives: less than  ten  inches  per  year.  The  area  of
southern Tunisia where parts of Star Wars were filmed  receives  on  average
only six inches of rain per year. Tropical rain forests  average  80  inches
per year. Arabs call the desert the "sea without water." This is  echoed  in
the name of Tatooine's "Dune Sea," the undulating field of sand dunes  where
Return of the Jedi's Sarlacc lives. This lack of  water  provides  the  main
challenge to life. In some parts of the Sahara, no rain has fallen  in  more
than twenty years.

     Then suddenly rain falls in a torrent, flooding across the landscape  ,
plowing boulders ahead of it and cutting channels into the ground before  it
finally sinks into the subsoil. We see signs  of  similar  rain  erosion  on
Tatooine, which has several dry riverbeds: one where Artoo  is  captured  by
the Jawas, and another by Jabba's palace. In the desert, the land is so  dry
that the air is often parched, with only 2 to 5  percent  humidity.  Clouds,
then, are rare, and sunlight beats directly down, with up to 95  percent  of
it reaching the ground. In midday, heat-absorbing black rock can  reach  185
degrees, way too hot  to  walk  on.  Since  water  serves  as  a  moderating
influence on temperature, areas  without  water  heat  and  cool  much  more
quickly.

     At night, the temperature can plummet to only 50 degrees. Such  extreme
temperature variations actually cause rock  to  crack  and  burst.  As  Luke
Skywalker stands in the heat of the  day  on  a  mountain  cliff  above  Mos
Eisley, he may hear a series of loud cracks like cannon fire as the mountain
rock fractures . As rocks break  off  and  fall  down  the  mountains,  they
shatter into smaller pieces. Weathering reduces these fragments to sand  and
even smaller dust. Another phenomenon Anakin and Luke may be  familiar  with
is ghost rain. In the desert, a hot layer of air often forms just above  the
ground. Rain may begin to fall, but when  it  hits  that  heated  layer,  it
evaporates, never reaching the ground. Contrary to the vision you  may  have
of it, a desert is not all sand.

     Sand and dust are simply the endpoints of erosion of rock by  heat  and
wind. The Sahara is only 20 percent sand. The remainder includes  mountains,
plateaus, piles of slag, gravel-covered wastes, ravines, and canyons. We see
many of these features on Tatooine. The Jawas hide in caves in a rocky cliff
face. Luke catches up with the renegade Artoo  in  a  canyon,  and  Threepio
falls off a plateau when the Sand People attack. In The Phantom Menace, more
of Tatooine's topography is revealed in a white-knuckle pod race.  The  race
course seems to be part of a network of deep twisting ravines and  crevasses
that includes some bizarre stone formations, such as  a  series  of  natural
stone arches. The Sahara's Tassili n'Ajjer  Plateau,  an  area  of  southern
Algeria, provides a striking parallel to this part of Tatooine.

     The Tassili Plateau is made up of hundreds of huge blocks of  sandstone
that split apart long ago. Narrow steep-sided  ravines,  up  to  2,000  feet
deep, separate these blocks. Numerous shallower  canyons,  up  to  200  feet
deep, crisscross the plateau. German naturalist Uwe George, author of In the
Deserts of This Earth, says, "The canyons run through the plateau  like  the
streets of a large city, with 'apartment houses' between them."

     Within this city are dead ends, intersections,  tunnels,  caves,  stone
needles 100 feet high, and bridges arcing like overpasses over the  streets.
These bizarre formations were caused by wind and water  erosion,  the  water
erosion taking place long ago when the Sahara had  a  wetter  climate,  long
replaced by wind erosion in this extremely  and  region  .  Since  the  wind
carries sand and dust, high winds, according to  Uwe  George,  act  like  "a
sandblasting machine." It's certainly reasonable to find such formations  on
Tatooine. They also suggest that there may once  have  been  more  water  on
Tatooine than there is now. Before we try to figure out  what  Tatooine  may
have been like in the past, let's examine its current condition.

     As far as we can tell, the entire planet appears to be a desert.  Earth
has a much more varied climate, with only 30 percent of the continents being
desert. Deserts form in particular areas because of a  variety  of  factors.
Most terrestrial deserts  lie  near  the  Tropic  of  Cancer  or  Tropic  of
Capricorn, where the sun's rays are at their strongest during  the  Northern
Hemisphere's summer and  the  Southern  Hemisphere's  summer,  respectively.
Patterns of air circulation, ocean currents, and elevation  also  contribute
to the formation of deserts. Once formed, deserts  tend  to  expand.  Strong
winds dry out the topsoil of neighboring lands and blow it away.  Sandstorms
cause even more dramatic erosion. They can sand the paint off a car and wear
the landscape down to bare rock.

     The deserts on Earth are expanding in this way, with the Sahara growing
by forty square miles each day. Even if Earth's continents did  become  huge
deserts, though, our planet would  still  have  one  major  difference  from
Tatooine: oceans. We don't see any large bodies of water  on  Tatooine,  and
unless they're hiding on the far side of the planet, we have to assume there
are none.

     Dr. Condie finds the lack of surface water hard to accept. "To  have  a
whole planet that is a desert and yet to have moisture in the  atmosphere  I
think would be difficult."

     As we discussed earlier, scientists believe most of the free  water  on
Earth came from water locked in the  rocks,  and  since  Tatooine  generally
seems quite similar in composition to Earth, we  can  assume  that  Tatooine
similarly has water locked in its rock. On Earth, that water  was  liberated
by volcanic action. On Tatooine , then, less volcanic action may have  freed
smaller quantities of water. Why  would  Tatooine  have  had  less  volcanic
activity? Perhaps Tatooine has smaller quantities  of  radioactive  elements
that serve to heat it. Or if the composition of Tatooine is about  the  same
as Earth, then perhaps Tatooine is less massive than Earth.

     A less massive planet would have less internal heat. An example of such
a planet is Mars, which is only about half the size of Earth. Mars has  some
volcanic activity, but it has been decreasing steadily, and Mars  has  never
been as geologically active as Earth. Thus it's not too difficult to explain
why a planet would have less  free  water  than  Earth.  With  this  theory,
Tatooine always would have had less free water, and it always will have less
free water. Signs of water erosion, then, would  simply  be  the  result  of
irregular downpours, as occur in the desert.

     In proposing ways Tatooine differs from Earth, though, we  have  to  be
very careful. As discussed  earlier,  terrestrial  life  survives  on  Earth
because of many different factors  in  delicate  balance  .  A  planet  that
differs significantly from Earth in any way  will  likely  not  be  able  to
support human life. For example, if Tatooine had the  geologic  activity  of
Mars, human life could not survive on it.  Remember  that  currents  in  the
liquid outer core create a planet 's magnetic field. Because of its  minimal
internal activity, Mars has a very weak magnetic field, which does not  keep
damaging high-energy charged particles away  from  the  surface  as  Earth's
magnetic field does. So we must propose only incremental differences between
Tatooine and Earth, slight changes that might be just enough to  create  the
differences we see. Tatooine, after all, is much more like Earth than any of
the planets in our solar system.

     While we're doing this, please be aware that any theories  we  consider
will be very speculative. A planet is an extremely complex system, with many
different factors interacting, and we don't yet fully  understand  how  they
all affect each other. After all, when it comes to planets, we only  have  a
few examples to work with, and only one that we've studied in detail. If  we
want to theorize that Tatooine had more water  earlier  in  its  history-and
accounting for signs of erosion is only one  reason  we  might  want  to  do
this-we need to work a little harder. One of our local  planets  provides  a
handy comparison. While Mars is now a desert  planet,  it  is  covered  with
signs of water erosion.

     Scientists believe Mars once may have been warmer and wetter. But  what
happened to the water? Current theories involve several different  processes
occurring together.  One  of  these  in  particular  might  be  relevant  to
Tatooine. Scientists believe that some of  the  water  on  Mars  has  simply
evaporated from its atmosphere into space.

     A planet holds an atmosphere to it by gravity.  The  molecules  in  the
atmosphere are constantly moving around,  colliding  with  each  other.  The
higher the temperature, the faster the molecules  move  and  the  more  they
collide with each other. In these collisions, a lighter molecule can pick up
more speed than a heavier one. A lighter molecule may then  actually  attain
the  escape  velocity  required  to  overcome  the  planet's   gravitational
attraction. It will escape the atmosphere and head off into space. Molecules
are constantly leaking from the atmosphere of any  planet  into  space.  The
less massive the planet, the lower the required escape velocity.

     Dr. John Schilling, research engineer at SPARTA, Inc.,  explains,  "The
occasional molecule in the upper atmosphere  picks  up  enough  speed  in  a
'lucky' series of collisions to escape into interplanetary space." The  rate
of evaporation depends on the mass of the particular molecule, the  mass  of
the planet, and the air temperature. These factors allow light elements like
hydrogen and helium to escape from Earth's atmosphere. In the weaker gravity
of Mars, molecules as massive as water can sometimes escape, even though the
temperature, and so the velocity of the molecules, is lower.

     We really don't want Tatooine to have gravity as weak as that of  Mars.
Mars, after all, has only a very thin atmosphere and can't  support  complex
life. If water molecules can escape the atmosphere too easily, we won't have
any water left, and we'll lose other elements as well. Yet we don't need  to
lose an entire water molecule to lose water. Ultraviolet radiation from  the
twin suns can strike a water molecule in the upper atmosphere and  break  it
into hydrogen and oxygen. The light hydrogen could escape, while the heavier
oxygen remains trapped in the atmosphere. The water has virtually been lost,
though the entire molecule did not leave the planet.

     This process occurs on Earth, though at a  very  low  rate,  since  our
atmosphere acts as a shield against most ultraviolet radiation.  Only  if  a
molecule makes it to the upper part of the atmosphere will it likely be  hit
by ultraviolet rays. If we theorize that Tatooine is a bit less massive than
Earth, then it might start out with less free  water  in  the  first  place.
Water molecules in the atmosphere could rise higher in the lighter gravity ,
more easily reaching the upper  portion  where  they  would  be  exposed  to
ultraviolet r adiation.

     We could even imagine that Tatooine's twin suns  put  out  a  bit  more
ultraviolet radiation than our sun-though not too much, unless you want Luke
and Anakin to get skin cancer. Another factor could contribute as  well.  If
Tatooine does have a magnetic field just a bit weaker than Earth's, it would
offer slightly less protection from high-energy charged particles in  space.
These particles could also  break  apart  water  molecules.  Thus  we  could
explain a very slow loss of water from the atmosphere, leading to a  gradual
drying of the planet over billions of years.

     Humans happened to find and colonize Tatooine during the  few  tens  of
millions of years when it had lost most of its moisture but still had enough
remaining to make it habitable. So if we're theorizing that  Tatooine  is  a
"bit less massive" than Earth, how massive is that?

     Mars, at about half the size of Earth and just  10  percent  the  mass,
seems too  small.  Dr.  Michael  Burns,  a  theoretical  astrophysicist  and
president of Science, Math, and Engineering , Inc., believes a planet  about
two-thirds the size of Earth, with a mass about 30 percent  that  of  Earth,
might fit the bill. Even though Tatooine may be very slowly losing water, at
the time we see it, it still retains a fair amount. Moisture exists  in  the
air of Tatooine. We see clouds in the atmosphere, and Luke lives on Owen and
Beru's moisture farm,  which,  according  to  the  Star  Wars  Encyclopedia,
condenses moisture from the  air.  What  water  Tatooine  has,  then,  would
circulate through Tatooine as it does in the  desert.  Water  vapor  in  the
atmosphere would give rise to ghost rains and rare downpours that erode  the
landscape and then sink into the ground.

     Those downpours  would  provide  groundwater  that  could  be  accessed
through deep wells and that would perhaps, in  depressions  in  the  ground,
give rise to the occasional oasis. The Sahara has significant quantities  of
groundwater. Some of Tatooine 's rain and groundwater would  then  evaporate
into the atmosphere , continuing the cycle.  It's  very  expensive  to  pump
water up from signficiant depths, so perhaps farming the moisture  from  air
would be cheaper and easier.

     Dr. Condie points out that "In some areas on Earth you have a hard time
getting water out of the ground. The water table may be low or  nonexistent.
Yet in those cases you just go  to  a  well,  or  pipe  in  the  water  from
elsewhere." If water is this  difficult  to  pump  everywhere  on  Tatooine,
though, and condensation has somehow been made easy, that could be a  better
solution. If many farmers are doing it, this could  lead  to  a  significant
depletion of the slight humidity in the air. Luckily,  Tatooine  seems  only
sparsely populated. I said  earlier  that  positing  a  wetter  history  for
Tatooine was helpful for more than just explaining erosion.  If  the  theory
that life on Earth originated near underwater hydrothermal  vents  is  true,
then it's hard to imagine how life began on Tatooine.

     We can imagine primitive underground  life  developing,  as  scientists
think might exist on Mars, but what about more  complex  life?  Dr.  Jakosky
says, "If you're going to get big  organisms,  I  think  you  need  standing
bodies of water. Microbes can live in the pore space of rocks in the  crust.
But anything bigger needs room to move." So if Tatooine had  more  water  on
its surface at one time, that would make it easier to understand how complex
life might have evolved. What kind of life? You'll have to wait for the next
chapter to find out. Twenty years ago, most scientists would have said  that
planets are probably  rare,  habitable  planets  very  rare,  and  habitable
planets with all the ingredients for life extremely extremely rare.

     Now, planets appear to be  quite  common  in  the  universe,  habitable
planets a fair fraction of these, and the  ingredients  necessary  for  life
widespread. Life may be developing, living, and dying in  star  systems  all
around us. Although we might need  some  technological  assistance  when  we
visit, with a little help we should be able to survive on a wide variety  of
worlds. So in this huge population explosion, exactly what sort of neighbors
might we find?


     Aliens


     A black, triangular-headed alien with glimmering gold eyes pops  up  in
the local cantina. An ancient, eyeless slug  lurks  within  an  asteroid.  A
sinuous snakelike creature with a periscope for  a  head  prowls  the  Death
Star's garbage masher for tasty treats. One of the most  delightful  aspects
of Star Wars is the constant appearance of bizarre forms of alien life.
    Almost anywhere you go  in "a galaxy far, far away," alien life is there. 
You'll either land in it,  step on it, or get eaten by it. The skeleton of a 
of  a    Sandsnake   on a  Tatooine sand dune creates an echo of the past. A 
dragon-like  creature   lurks  in   an underwater cave on Naboo. Artoo falls 
into the  swamps of  Dagobah  and  is  almost instantly eaten, and almost as 
quickly spit out.   Wherever you go, whatever youdo, there will always be an 
alien there to do it with you. 
    When Luke   Skywalker entered that cantina twenty-two years ago, the way 
we   thought of aliens and the way they  were  treated  in  science  fiction
changed forever. No longer were we expected to  gawk  in  fascination  at  a
single alien species; the universe, according to  George  Lucas,  is  filled
with life. Not only do many planets develop life, but  on  any  one  planet,
many different species evolve, just as on Earth.  Even  in  environments  as
inhospitable as Tatooine , Hoth,  or  an  asteroid,  life  finds  a  way  to
survive. But what sort of life would develop in these various environments ?

     If alien life is indeed plentiful,  as  recent  scientific  discoveries
lead us to believe, will it look anything like  Star  Wars  aliens?  Is  the
universe likely to be home to glowing-eyed Jawas,  wriggling  Hutts,  cuddly
Ewoks, hungry Sarlaccs, gooey Mynoks, and goofy Gungans?


     HOW ALIEN ARE ALIENS?


     On Earth, we're presented with a huge variety  of  life-organisms  with
leaves, wings, trunks, claws, flippers, tentacles, hooks, antennae ,  horns,
quills, scales, fur, fangs, shells, slime. Organisms that reproduce  through
spores, seeds, division, sex with another, sex  with  themselves.  Organisms
that live inside other  organisms;  organisms  that  live  attached  to  the
outside of other organisms; organisms that live in water, air,  rock,  dirt,
blood, ooze. Over the history of our planet, tens of billions  of  different
species have existed .

     Dr. Pickover says,  "When  I  gaze  upon  crazy-looking  crustaceans  ;
squishy-tentacled jellyfish;  grotesque,  hermaphroditic  worms;  and  slime
molds more alien than the wildest dreams of science fiction writers, I  know
that God has a sense of humor, and we will see this reflected in other forms
in the universe." Considering that such a variety of creatures developed  on
our single planet, it seems unlikely that aliens will happen to  have  human
characteristics or form.

     With two arms used to perform tasks, two legs used to walk, and a  head
with sensory apparatus, many Star Wars aliens have the  general  form  of  a
human: Yoda, the Jawas, the Sand  People,  jar  jar  Binks,  the  Wampa  ice
creature, Greedo, Admiral Ackbar, the Ugnaughts of Cloud  City,  the  lizard
bounty hunter Bossk, the tentacle-headed Bib Fortuna,  singer  Sy  Snootles,
Lando's copilot Nein Numb, Chewbacca, the Ewoks, the cantina band, and  many
other miscellaneous aliens in the movies. Yet Star  Wars  provides  us  with
many non-humanoid aliens as well, offering a wider variety  of  aliens  than
any other science  fiction  movies,  with  Banthas,  Tauntauns,  Sandsnakes,
Sarlaccs, Hutts, Dewbacks, Mynoks, space slugs, and many more.

     These make the Star Wars universe feel real, vibrant, and  unique.  Dr.
Michio Kaku, Henry Semat  Professor  of  Theoretical  Physics  at  the  City
University of New York and author of Hyperspace and Visions  ,  agrees.  "In
Star Wars, the aliens don't look like us anymore. They tried to have  aliens
with different architectures. In that sense, Star  Wars  is  more  realistic
than some of the stuff I've seen."

     But is this what alien life would really be like? The most likely alien
life we'll encounter will resemble terrestrial bacteria. Bacteria  developed
first on Earth about 3.85 billion years ago, and remained the sole  type  of
life for billions of years.  Multicellular  organisms  didn't  appear  until
about one billion years ago, and animals evolved only  six  hundred  million
years ago,  quite  recently  in  Earth's  life  span.  Even  though  complex
life-forms are now common on Earth, bacteria still make up the  majority  of
life on our planet. Dr. Stephens believes we're going to find the same ratio
of primitive to more sophisticated life everywhere  in  the  universe  .  "I
think what we're going to find is enormous  numbers  of  planets  and  moons
where the first steps of life have occurred, even up  to  the  formation  of
things that resemble bacteria."

     So we'd likely encounter many planets with primitive life-forms, and  a
much smaller number with more complex life. Dr. Jakosky comes  to  the  same
conclusion. "It took three billion years on Earth to go  from  single-celled
organisms to multicellular complex organisms. That means that's not a likely
event. Once we got complex organisms one billion years  ago,  though,  Earth
experienced a rapid explosion  of  diversity  of  life.  Once  complex  life
develops, tremendous diversity is likely to arise."

     What would this complex life be like? To consider what alien life might
look like, it's helpful to think about how terrestrial  life  came  to  look
like  it  does.  Species  are  created  through  evolution.  Random  genetic
mutations occur as organisms live and reproduce. If a mutation happens to be
favorable, helping the organism to survive in its  particular  surroundings,
it's more likely to reproduce and pass that mutation on to offspring. If the
mutation happens to be unfavorable, the organism may die  before  it  has  a
chance to reproduce, and so the mutation will disappear from the gene  pool.
Evolution involves a lot  of  chance  circumstances,  both  genetically  and
ecologically.

     Dr. Jakosky calls these chance circumstances "accidents of history."  A
mutation could occur that makes a fish much more fit for life  in  the  tiny
pond where it lives. Yet it happens to be born in a dry year, and before  it
has a chance to reproduce, the pond dries up  and  the  fish  dies,  so  the
mutation is never passed on. At the same time, another fish is born that has
a mutation that pond. Normally pond. Normally , the  first  fish  would  eat
this one for breakfast. Yet as the pond dries up, the second fish  finds  it
can survive for brief periods outside water, long enough, in fact,  to  flop
over to a larger lake a few feet away that doesn't dry up.  This  odd  fish,
which can move between land and water, survives and reproduces, and  perhaps
becomes the ancestor of all vertebrates, including man.

     If instead of a dry year it had been a year of heavy rains,  that  fish
would never have survived, and quite different creatures might have evolved.
Dr. Jack Cohen, reproductive biologist and consultant  for  the  Mathematics
and Ecosystems Departments at the University of  Warwick,  points  out  some
interesting characteristics of the fish that came out  of  the  water  three
hundred million years ago to become the ancestor of all vertebrates. "It had
its airway crossing its foodway, and it had a reproductory system mixed with
its digestive system. There were many fish that didn't have those  mistakes,
and one of those could have crawled out of the water."

     Chance, then, has played a large role in  our  development,  making  us
creatures that breathe and eat through the  same  opening,  our  mouth,  and
reproduce through organs intertwined with our excretory system .  Many  Star
Wars aliens seem to share these mistakes-at least they  appear  to  use  the
same opening to breathe  and  eat,  which  seems  quite  odd.  We  can  only
speculate on their reproductory systems . How these "accidents  of  history"
might combine on another planet is very difficult to predict. Dr. Tim White,
professor  of  integrative  biology  at  the  University  of  California  at
Berkeley, believes that "it's hard for us to imagine other kinds of life.

     Animals adapt, through evolution, to their environment,  and  we  don't
know about extraterrestrial environments  outside  our  solar  system  .  In
addition, you have chance events that end up  knocking  things  off  balance
every once in a while, and thereby structuring the fabric of life and making
its evolution unpredictable." Even a planet  similar  to  Earth  would  most
likely give rise to significantly different organisms. In  fact,  scientists
believe humans wouldn't even have evolved here  unless  the  dinosaurs  were
killed off by a huge meteoroid sixty-five million years ago.

     Dr. White says, "You take away this event or that event, and we're  not
having this conversation." Most likely, aliens are going to be stranger than
we can  imagine  .  Dr.  Pickover  agrees.  "Considering  that  octopi,  sea
cucumbers, tube worms, and pine trees are all very closely related to us, an
alien would look less like us than does a squid." So is there no way to tell
what aliens might look like?

     Well, aliens are life-forms,  like  us,  and  face  some  of  the  same
problems we  face-problems  of  movement,  sensing  and  manipulating  their
environment, nourishing themselves,  and  reproducing.  Solutions  to  these
problems that are valid on Earth ought to be equally valid in "a galaxy far,
far away." Thus, even though alien life would have taken  a  very  different
evolutionary course and would have DNA quite different than ours-if  it  has
DNA at all-it might end  up  with  some  similar  characteristics.  Life  on
planets has to deal with gravity, which will probably lead to organisms with
a specific top and bottom. Sophisticated life that moves will probably  have
a front and a back. To sense their environment, organisms need one  or  more
of the following abilities: to detect a useful spectrum  of  electromagnetic
radiation (to see); to detect changes in the surrounding atmosphere (to hear
and smell); to detect heat and evaluate surfaces (to touch); and to evaluate
food (to taste). If an organism must seek out food, then it would make sense
to concentrate these sensory organs at the front end of the organism.

     To  manipulate  the  environment,   sophisticated   organisms   require
appendages. To move through that environment ,  they  need  some  method  of
locomotion. Some sort of symmetry will make mobility easier. But how  likely
is it that a creature might move using two limbs like a man, four limbs like
a giraffe, a muscular trunk like a snake or a fish, wings like a bird or  an
insect, a tentacle like an octopus, or some other method?

     We can get some idea of how common or likely a certain  solution  might
be by examining how many times that trait independently developed on  Earth.
Solutions that developed in different times and places must be  particularly
useful or efficient. For example , flight developed three separate times  on
Earth: once with birds,  once  with  insects,  and  again  with  bats.  Eyes
developed four separate times.

     So these solutions may be a bit  more  likely  to  develop  on  another
planet. Dr. Pickover points to three quite  unrelated  animals:  a  dolphin,
which is a mammal; a salmon, which is a fish; and an ichthyosaur,  which  is
an extinct reptile. "They all swam in coastal waters darting about in search
of small fish to eat. These creatures  have  very  little  to  do  with  one
another biochemically , genetically, or evolutionarily, yet they all have  a
similar look. They are nothing more than living, breathing  torpedoes.  They
have evolved streamlined bodies to help  them  quickly  travel  through  the
water. We might expect aquatic aliens that  feed  on  smaller,  quick-moving
prey to also have streamlined bodies."

     Other solutions have occurred only once on Earth, making them seem less
likely to occur on another planet. For example, while all land animals  have
developed methods of acquiring water, only one, the elephant,  uses  a  long
trunk. Dr. Stephens believes that the form these solutions take  is  largely
determined by physical constraints, which in turn are  consequences  of  the
laws of physics, chemistry,  and  biology.  For  example  ,  let's  consider
fingers or, more generallay, digits. If aliens arrive  here  in  spaceships,
how many digits are they likely to have?

     An intelligent, space-faring race needs to be able  to  manipulate  its
surroundings with limbs, and digits at the end of those limbs. Dolphins  may
be intelligent, but they'll never light a fire and never build a  spaceship.
The realities of the physical world make  certain  numbers  of  digits  more
functional than others.

     "Is there an ideal number?" Dr. Stephens asks. "Clearly the  answer  is
yes." One digit is obviously not going to be terribly useful  at  performing
complex  tasks.  Similarly,  two  digits  aren't  very  good,  which  you've
discovered if you've ever tried to do anything delicate wearing mittens. Dr.
Stephens says, "Three is some kind of minimum threshold if you're  going  to
do serious manipulations." If three is the minimum,  what  is  the  maximum?
"When you get up to seven or eight,  I  think  you  have  a  difficult  time
accommodating that many digits on the end of an extremity and  things  would
start becoming awkward." While we haven't done experiments that might  prove
five is the ideal number, Dr. Stephens believes five likely is the ideal.

     "What we've learned recently is that our amphibian  ancestors  did  not
have five digits but had six or seven digits. Evolution and selection  chose
five for us, suggesting five is some  sort  of  ideal."  Dr.  Stephens  then
believes that intelligent aliens would likely have five digits,  as  we  do.
Since certain physical constraints are valid throughout the universe  ,  Dr.
Stephens concludes that even though intelligent aliens  might  have  evolved
from vastly different organisms than we did, they may very well be humanoid.
"The probability of finding an alien that looks like us is perhaps  as  high
as 80 percent."

     Yet he seems to be in the minority. Dr. Cohen suggests the opposite  is
true. "Finding another planet with our kind of dinosaurs or people  is  more
unlikely than finding a remote Pacific island on  which  the  natives  speak
perfect German." Aliens  would  have  gone  through  an  entirely  different
evolutionary procedure, suffering different "accidents  of  history,"  which
would have led to different adaptations.  Dr.  Pickover  considers  humanoid
aliens "far-fetched. Some of the Star Wars creatures seem a little too human
looking considering the quite different evolutionary pathways we'd  expect."
For Dr. White, the most troubling characteristic of  intelligent  aliens  is
that most of them are bipedal. "There is no  necessary  correlation  between
bipedality and high intelligence ."

     Dr. Kaku believes there are only  three  key  elements  an  intelligent
alien must have. "An opposable thumb or tentacle of some sort,  language  to
communicate, and stereo eyes to hunt and strategize. Other  than  that,  all
bets are off." Dr. Jakosky agrees. "There's no intrinsic evolutionary  drive
toward a human shape, even though we can make all these arguments about  how
wonderful we are."

     While the number of aliens with human characteristics may be high, Star
Wars aliens embody many nonhuman characteristics as well. Do the aliens make
use of more "common" solutions, which would make them more likely aliens; do
they use solutions that occurred  only  once  on  Earth,  making  them  seem
unlikely to occur ever again; or do they use uniquely alien solutions?



     FUZZBALL OR GENIUS?


     If we do find alien life, will it be  intelligent?  Star  Wars  abounds
with intelligent aliens, from Chewbacca to Jabba to Greedo  to  Jar  Jar  to
Yoda. When I speak of intelligence here, I mean intelligence  comparable  to
the sophisticated self-conscious intelligence humans have. My iguana, Igmoe,
is extremely intelligent, yet even I won't claim that he has the  powers  of
thought, reasoning, and understanding that we have-at  least,  he  fails  to
appreciate Star Wars, which is a failing of intelligence in my opinion.

     Some scientists  believe  that  while  alien  life  may  be  plentiful,
intelligent I alien life is  much  less  probable.  They  argue  that  while
evolution works through "survival of the fittest," being  smarter  does  not
always make you more fit. Organisms can be very successful in surviving  and
reproducing without high intelligence.  Cockroaches,  for  example,  are  an
extremely hardy species and may well outlive man. If additional intelligence
was an advantage . for them, so the argument goes, then we should have  seen
them growing progressively more intelligent over  the  generations,  and  we
haven't. Of course, I don't know anyone who's administered  an  intelligence
test to a cockroach. Dr. Jakosky agrees that evolution  doesn't  necessarily
encourage intelligence.

     "Organisms tend to have a brain just big enough to  handle  their  body
and not a lot extra. We're the  exception."  He  points  out  that  in  four
billion years and tens of billions of species, only man has developed  self-
conscious intelligence, "so that says it's an uncommon event." Or  in  other
words, it's an uncommon solution to the problem of  survival.  Dr.  Pickover
sees our intelligence as an evolutionary accident.  "I  believe  that  alien
life will be unintelligent and unable to build crafts to leave their  world.
This is the prime reason why the universe of Star Wars, which  thrives  with
intelligent life, is unrealistic."

     Yet other scientists believe intelligent life may be more common. While
intelligence within a particular species may not increase, scientists  point
out that as life has evolved on Earth into more complex, advanced forms, the
size of the brain relative to the body has increased, and  intelligence  has
increased . And while human-level intelligence may have only developed  once
on this planet, lower levels of intelligence developed independently in  all
the different classes of animals. Astronomer Carl  Sagan  argued  that  more
intelligence is beneficial to any organism, helping it find  food  and  cope
with changes in its environment. In that case, intelligent  organisms  would
have a better chance of survival.  Thus  intelligence  would  be  a  natural
consequence of life and evolution.

     Dr. Frank Drake, head of the SETI Institute, estimates ten thousand  to
a hundred thousand intelligent civilizations exist in  our  galaxy.  But  if
intelligent alien life is common, then why haven't any aliens dropped in  on
us? This question is known as Fermi's paradox, and scientists have struggled
for an explanation for more than two hundred years. Some of the explanations
they've come up with?

     * Alien civilizations self-destruct before  they  develop  interstellar
travel. 

     * Aliens do visit us, but they   like to   keep   their  visits  secret.
Word could get back to a pesky bounty hunter. 

     * The stars are  so  for  from each other, visits are just too difficult 
and expensive. Maybe if we  kicked in some money for gas.... 

     * Earth is just too for from the bright center  of the universe to draw 
alien tourists. 

     * Aliens prefer to stay home, put on  a pot of  stew, and  observe   us 
through the Force.



     DO YOUR EARS HANG LOW?


     Of all the alien species we meet in  Star  Wars,  we  know  the  native
planets of only a few.  Without  this  information  it's  difficult  to  say
whether their traits are likely or not. Even  with  this  information,  it's
very difficult to draw any firm conclusions. For example, say  giraffes  are
not a species on Earth but an alien species in the next Star Wars movie.  We
could speculate endlessly about the viability  of  such  an  alien  and  the
bizarre environment that might have spawned such a creature.

     That long, heavy neck? How unlikely! It would fall on its face. It must
come from a planet of light gravity that allows  it  to  survive  with  such
skinny stick legs. The planet must be covered with  trees  that  hold  their
leaves an enticing fifteen or twenty feet off the ground. These  conclusions
seem reasonable , yet every one is wrong.

     Thus, any speculation about specific aliens can  be  little  more  than
educated guesses at this point. One factor may help a bit. Since the  aliens
we tend to see in the  movies  are  those  that  can  survive  in  the  same
environments as humans, we  can  assume  that  they  probably  developed  in
environments not radically different from Earth. Now let's examine  some  of
our favorite aliens.

     The Phantom Menace introduces the lovable goofball  jar  jar  Binks,  a
native of Naboo. Jar jar has the basic  exterior  characteristics  discussed
earlier for complex, intelligent life: a top and bottom , a front and  back,
bilateral symmetry, sensory organs, a method of locomotion,  and  appendages
to manipulate the environment. Generally humanoid in shape, jar  jar  has  a
number of distinctive characteristics that actually make him  a  fascinating
mystery. Clearly the "accidents of history" that guided the evolution of jar
jar's species were much different than ours, but led to  a  body  form  that
generally has much in common with a human's. His long muzzle gives  him  the
look of a camel or horse, his long  ears  are  a  bit  rabbitlike,  and  the
patterning of pigment on his arms is reminiscent of a lizard. Jar jar's most
prominent trait--literally-is his eyes. Popping out from the top of his head
like two ears with an identity crisis, they  are  unlike  the  eyes  of  any
Earthly creature. The unusual location  of  the  eyes  and  their  structure
suggest that their position may be critical to the  survival  of  jar  jar's
species, the Gungans.

     While we don't know exactly where on Naboo the Gungans evolved or  how,
we do have terrestrial animals with some similarities  that  may  illuminate
jar jar's situation. In the crocodile, the nostril openings and the eyes are
the highest parts of the head. This allows the crocodile  to  float  on  the
surface of the water, with most of his body and head submerged, and yet  see
and smell his surroundings. Thus the crocodile  can  wait,  looking  like  a
floating log, until a potential meal comes to the edge of the water for  its
last drink. Then with a quick snap, it's mealtime . Perhaps the Gungans,  or
their ancestors, obtained their food by some similar method. Their  nostrils
are positioned high on their heads, though not as high as the eyes.  Another
terrestrial model offers a different possibility. Many crustaceans, as  well
as some insects and fish, have eyes on stalks. Eyestalks allow  the  eyes  a
great freedom of movement. While jar Jar's eyes are not  on  stalks  and  so
can't have the level of mobility of stalk eyes, his eyes still probably have
some mobility, with muscles at the base of the eyes allowing  them  to  tilt
forward or back or twist to one side or the other.

     In some creatures with stalk eyes, each eye is at the end of a  rod  of
cartilage. At the base of the rod is a muscle that controls the movement  of
the rod. Thus the rod can be moved around, aiming the eye in  virtually  any
direction. Since crustaceans tend to be slow moving and are  slowed  further
by the viscous water, they can't dart their heads about quickly  like  birds
to monitor their surroundings.

     Jar jar can move quickly, though. So it's unclear what advantage moving
eyes would have when he could move his head just as fast. Some  mobility  in
his eyes, though, can potentially  provide  a  wide  field  of  view.  If  a
creature is an herbivore, a wide field of vision is helpful  to  keep  watch
for predators sneaking up on it.

     In terrestrial creatures, most herbivores get a nearly 360-degree  view
by having eyes that face  to  the  side.  If  a  creature  is  a  carnivore,
stereoscopic depth perception is helpful to precisely target and  seize  its
prey. Carnivores then tend to have both eyes facing ahead. Jar jar's eyes do
seem to face ahead when at rest, so he may have the  best  of  both  worlds:
stereoscopic depth perception and  a  wide  field  of  vision  when  needed.
Another advantage of this construction is with the  eyes  removed  from  the
skull, there is more room for the brain.

     In many terrestrial species, brains and eyes  must  compete  for  skull
space. The larger the eye, the greater the visual resolution. So larger eyes
with sharper vision would be helpful to all creatures to  survive.  Yet  the
bigger the eyes,  the  less  room  is  left  for  the  brain.  Birds,  whose
high-speed flying requires sharp vision, give up more skull space  to  their
eyes than their brain. Removing the eyes from the skull would allow jar  jar
to have a bigger  brain  than  a  camel  or  horse.  This  solution  to  the
skull-space problem, though, makes the eyes  vulnerable  to  damage,  rather
than protected within bony sockets.

     Dr. Stephens points out, "If you look at any vertebrate  organism,  the
senses are quite well protected by bone. Even the crocodile has a  ridge  of
bone on top of its eyes. No vertebrate organism  I  can  think  of  has  any
sensory organ hanging out there in the breeze without protection." A fall on
the head could get squishy, and  a  predator  could  tear  jar  jar's  tasty
nuggets off in one  bite.  It  seems  the  eyes  must  offer  a  significant
advantage to make up for this danger.

     His eyes yield yet further information. Animals that live in  nocturnal
environments must develop very sensitive eyes,  eyes  that  have  both  very
large pupils to allow in as much light as possible  and  specially  designed
retinas to detect the dimmest light. The light-sensitive retina at the  back
of the eye is normally made up of two kinds of cells, rods  and  cones.  The
rods are sensitive to dim light, while the cones  handle  bright  light  and
provide color vision. Nocturnal animals have more  rods  than  cones,  which
gives them better night vision. But when these  animals  also  go  out  into
bright light, they have trouble coping. Their pupils can  contract  to  shut
out most of the blinding light, muscles in the eye tightening to  make  that
opening smaller.

     But the specific arrangement of the muscles sets a limit on how small a
round pupil can become. Even at its smallest, it may let in more light  than
a nocturnal creature can handle. A slit pupil, on the other  hand,  has  its
muscles arranged differently. When the pupil is dilated, it  appears  round,
yet when it contracts, the muscles can close  it  down  to  a  narrow  slit,
allowing only a tiny fraction of light to enter.  The  slit  pupil  is  much
better for  nocturnal  animals  that  also  venture  out  in  daylight.  The
crocodile, which is mainly nocturnal but also enjoys  basking  in  sunlight,
has a slit pupil. We can theorize that jar jar is mainly nocturnal as  well.
That must make it hard for him to adopt the diurnal schedule  of  his  human
companions .

     Qui-Gon may find him prowling around at night, like you'd find your pet
cat. Another clue to his lifestyle may be in his rather long, flexible neck.
Many terrestrial animals have developed long necks, so  it  seems  a  fairly
reasonable trait to find in an alien. Terrestrial animals use long necks for
a variety of reasons. Giraffes use them to reach leaves high off the ground;
storks use them to catch fish. We have a problem with any  theory  that  has
him using his neck to get food, though. A biped with two legs and two  arms,
like jar jar, would be much more likely to catch a fish with his  hands,  or
to reach up with a hand and pull a branch with some  tasty  leaves  down  to
mouth level.

     Dr. Stephens asks, "Why would you develop a long neck if your grasp  is
twice as high as your head?" Perhaps, if he is operating like  a  crocodile,
he waits until prey come close to his mouth and snaps them in, the long neck
giving him additional mobility. Or perhaps the advantage of the neck is  not
to reach food, but to elevate the eyes even further. Camels have  both  long
legs and long necks, which together serve to elevate their heads  above  the
blinding, choking particles of desert sandstorms . A  similar  environmental
condition could explain why jar Jar's body works so strongly to elevate  his
eyes. Perhaps a layer of ground fog tends to form during the  night  in  the
region where the Gungans evolved.

     This occurs in  different  areas  on  Earth,  such  as  river  valleys,
wetlands, or in coastal regions. The fog may tend to dissipate at a  certain
height, offering an advantage to those whose eyes are  above  the  obscuring
fog. Another interesting trait is jar jar's long muzzle, which on  Earth  is
common to quadrupeds. Quadrupeds tend to have long muzzles, since they  need
to use their mouths to hold and manipulate food as they eat it. Bipeds  with
arms, like humans, can use their hands to hold and manipulate food, so  they
don't need a long muzzle. Jar jar's muzzle leads Dr. Stephens to "expect him
to be very clumsy with his hands."

     Jar jar definitely has some coordination problems. One  final  clue  to
jar jar's nature is his huge, floppy ears. Large ears in terrestrial animals
help animals radiate excess heat into the surrounding  air.  Desert-dwelling
rabbits and other desert animals often have extra-large ears  to  help  cool
their blood. The large ears of African elephants  serve  the  same  purpose.
Prominent veins in the ears help bring the blood close to the skin's surface
for cooling. In addition, the elephant can flap his ears to  speed  cooling.
Jar Jar's ears may work in a similar way.

     They may also serve as communication devices. Elephants move their ears
to assert their dominance over other males and to  defend  their  territory.
Perhaps the movies will give us further clues as to whether jar  jar's  ears
function in this way as well. We can thus theorize that the Gungans may have
evolved in a hot climate where threatening predators lived.  Hunting  mainly
at night offered one method for avoiding the heat,  while  their  huge  ears
offered a method for dealing with heat when they come out  during  the  day.
Environmental conditions may have existed that made it difficult to see near
ground level, so that elevating their eyes offered great advantages. Or  the
placement of their eyes may have helped them surprise prey. Yet the eyes are
jar jar's Achilles' heel, and he must guard them  at  all  times.  One  good
tumble, and it's lights out.



     THE DAWN OF WOOKIEE


     Of all Star Wars aliens, the one I feel closest to is  Chewbacca.  Over
seven feet tall and more than two hundred years old,  Chewie  is  a  hulking
walking carpet, loyal, courageous, at times fierce, at times-when  his  nose
is telling him things no one else seems to notice-a bit skittish.

     According to the Star Wars Encyclopedia, Wookiees come from the  forest
planet of Kashyyyk, where they build cities a mile off  the  ground  in  the
tops of massive trees, rather like Ewoks. Their long limbs would  help  them
climb trees and swing from branch to branch. Claws on their feet, which  are
narrow and sharp, seem potentially helpful for climbing, though Chewie's are
clipped short-or perhaps they're just retracted, like a cat's. We can't  see
if Chewie has claws on his hands, since, like  most  of  his  body,  they're
shrouded in fur. Wookiees are very strong and can rip people's arms  out  of
their sockets, as Threepio well knows. They communicate through  a  language
of cries, howls, and grunts.

     While they can understand English, they are unable to speak  it.  Since
from outward appearances Wookiees are basically humans covered in fur,  they
seem like viable organisms, in which all  the  pieces  could  fit  and  work
together. Since body coverings like fur, hair, and feathers  have  developed
independently several times on Earth, fur on an alien seems reasonable. Such
body coverings help insulate a creature from external  temperature  changes,
so Wookiees most likely face temperature fluctuations similar  to  those  on
Earth and use a similar solution to cope with them.

     Chewie 's sharp teeth, front-facing eyes, and claws all point toward  a
carnivore. Chewie's sensitive sense of  smell  would  aid  in  tracking  and
locating prey. Humans hunt prey  as  well,  though-at  least  our  ancestors
did-so we might question why Wookiees have a better sense of smell  than  we
do.

     Scientists have recently found that 72 percent of the genes that govern
the formation of our olfactory receptors, the proteins  that  enable  us  to
smell, are mutated so badly that the receptors  don't  work.  Our  sense  of
smell has deteriorated greatly. Exactly when these mutations occurred is not
yet known; they may have occurred during human evolution, or  even  earlier,
before man developed. Apparently  a  high-powered  sense  of  smell  is  not
critical to man's survival, and so those with  less  effective  noses  still
survive .

     In Wookiees, smell must play a more critical  role.  They  may  need-or
have needed-smell to aid in the tracking of prey, which could  hide  in  the
dense forest. Or they may use their sense of smell to detect the emotions of
other creatures. An angry snake, for example , has the distinctive smell  of
a wet dog, and knowing when a snake is  angry  could  come  in  very  handy.
Wookiees may  also  use  smell  to  send  signals  to  each  other,  marking
territory, indicating a desire to mate, or  warning  of  danger.  Since  the
vocabulary of Wookiees may be limited, scents could offer another method  of
communication . A dog's sense of smell is one million times  more  sensitive
than ours.

     If Chewie's is equal to or even greater than this, he may be getting  a
wealth of information through his nose.  He  could  tell  whether  Jabba  is
hiding bounty hunters with blasters in the next room, a caseload of  spices,
or a frozen Han Solo. A  strong  sense  of  smell  could  even  explain  why
Wookiees seem rather emotional. Scientists  believe  smell,  more  than  any
other sense, evokes strong feelings. The smell of the sweater of a loved one
calls up a vivid sense  of  that  person,  triggering  strong  memories  and
feelings; the smell of fresh-baked chocolate-chip cookies triggers  pleasure
and excitement (in  me,  anyway).  Odors  can  be  informative,  disgusting,
delightful, frightening, and evocative.

     Scientists believe that smell was one of the first senses to develop in
terrestrial life. While information from our other sensory organs is relayed
to the neocortex, the part of the brain involved in  higher  thought,  scent
information is passed directly to the most primitive part of the brain,  the
limbic system, and particularly an ancient structure  called  the  amygdala.
The amygdala is involved in storing emotional memories and can imbue  events
with intense emotions.

     In our primitive ancestors, a smell triggered a strong emotion that  in
turn triggered a behavior: good food-eat! Today, while reason  may  keep  us
from acting on our desires-keep your hands  out  of  the  cookie  jar-scents
retain their direct line to our  emotions  .  These  brain  connections  are
largely the result of  evolutionary  "accidents  of  history,"  yet  perhaps
Chewie's senses are wired in a similar way. With his more refined and  acute
sense of smell, scents may call up  powerful  emotions  in  him.  While  the
Wookiees' ability to smell is much greater than ours, their ability to speak
seems much more limited. In this way, Woo- kiees are similar to chimpanzees.
Chimpanzees  communicate  by  expressions,  gestures,  and   many   distinct
vocalizations, including screams, roars, hoots, and grunts.

     They lack the ability to articulate the variety of sounds man can. Many
elements contribute to man's ability, including the lips, tongue, teeth, and
the hard and soft palates on the  roof  of  the  mouth.  The  most  critical
element is the larynx, where the vocal cords are  located.  In  humans,  the
larynx is lower in the throat than in apes.  This  change  occurred  as  man
began to walk erect, his brain size  increased,  and  the  location  of  the
skull's fastening to the spinal cord shifted to better balance the head. The
lower position of the larynx creates a tubular cavity  in  which  sound  can
resonate. Our relatively low-pitched speech arises from this cavity.

     The structure of the chimpanzee's larynx doesn't allow it to make  many
of the sounds needed for human speech. But they have been taught  to  say  a
few limited words, such as "mama" just like in Planet of the Apes. Wookiees,
then, may not have their larynxes positioned in a way that  allows  them  to
reproduce human speech.

     And why should they? It seems much more believable that aliens wouldn't
be set up with the exact structure needed to reproduce  human  sounds.  With
his great number of similarities to us, Chewie doesn't pose as  difficult  a
puzzle as jar jar. Yet he  does  raise  one  compelling  question:  Why  are
Wookiees bipeds? Bipedality has evolved  a  number  of  different  times  on
Earth, in dinosaurs, kangaroos, birds, and hominids. So it seems a trait  we
might possibly find in aliens. Yet is it a trait we  would  likely  find  in
Wookiees?

     We don't know if the Wookiees always lived in the  trees,  or  if  they
only moved there recently, once their level of technology  allowed  them  to
construct cities in the treetops. Yet it  seems  odd  that  a  species  that
evolved on the ground would suddenly decide to move up into the trees.  They
would feel more at home on solid ground, the animals  that  served  as  food
would be on the ground, and the conditions  most  favorable  to  their  body
structure and lifestyle would be on the ground. Climbing a mile down to  the
ground to hunt for dinner and a mile back up would make hunting a  difficult
proposition. It seems more likely, then, that Wookiees always lived  in  the
trees, and that they're able to satisfy all  their  needs  without  climbing
down to the surface.

     If the Wookiees did evolve in the trees, then, as seems more likely, we
might wonder why they'd develop a bipedal gait. Walking upright doesn't seem
the easiest way to get around on a tree. Even if you could  balance  upright
on a gigantic tree branch, why risk it?

     Quadruped tree dwellers can move with  great  agility  and  speed.  Dr.
White would prefer to have more information  before  speculating  about  the
evolution of the Wookiee. "In the unlikely event that I was presented with a
real, rather than imaginative, Wookiee, I'd like to  check  out  its  living
relatives and its ancestors, as much as we could figure out from the Wookiee
fossil record, in order to explain where that creature came  from."  In  the
absence of that information, though, can we learn  anything  from  comparing
Woo- kiees with Earth's tree dwellers? A  four-limbed  creature  needs  many
specific characteristics to walk on two limbs. The bones  of  the  vertebral
column, pelvis, leg, and foot need to have the  proportions  and  shapes  to
withstand the stresses placed on them and allow easy movement.  The  muscles
of the trunk and thighs need to develop the ability to balance  and  support
the body's weight and to propel it forward.

     Scientists believe that  a  tree-climbing  life  helped  prepare  man's
ancestors to walk on two legs. Tree climbers  tend  to  develop  front  legs
somewhat different than their back legs, the front limbs reaching  for  food
or  branches,  and  the  back  legs  supporting  the  weight  of  the  body.
Anthropologist Michael Seaman at Yale  University  points  out  that  "Since
they're climbing up and down all the time, they hold their torsos erect."

     These adaptations actually serve as the preliminary  changes  necessary
to prepare for a biped gait. So climbing creatures that evolve  into  bipeds
seem reasonable . Yet the accepted theory for many years has been that a key
element in the development  of  the  biped  gait  in  man's  ancestors,  the
hominids, was a change in climate. About four million years ago, the climate
on Earth began to get drier. East Africa, which had been a  moist  woodland,
began to change into an open grass- and  scrub-covered  savanna,  the  trees
dying off. Man's ancestors then had to leave the trees and adapt to life  on
the ground. In fact, footprints preserved in  volcanic  ash  reveal  bipedal
locomotion had developed in this region 3.6 million years ago.

     If the savanna theory  is  true,  and  bipeds  did  develop  because  a
climactic change led hominids to move from the  trees  to  the  ground,  one
might then wonder how Wookiees-and Ewoks-ever became bipeds. Since they both
are said to live in trees on heavily forested planets, and  we've  theorized
that they evolved in these trees, the conditions seem incompatible with  the
savanna theory. In the last five years, though, the savanna theory has  been
challenged by new fossil discoveries and revised estimates  of  the  climate
during the development of hominids.

     It's now believed that Africa's climate did not become particularly and
until 2.8 million years ago, while we  have  recently  discovered  signs  of
bipedal locomotion as early as 4.2 million years ago. The recent discoveries
of two previously unknown hominid species older than any  before  found  are
adding to the uncertainty. There are even indications  that  bipedalism  may
have  developed  independently  more  than  once  in  different  species  of
hominids, which would make it a somewhat more likely trait for aliens. While
the savanna theory has been thrown into serious doubt, the problem  is  that
scientists have no clear theory to replace it.

     The leading contender appears to be one proposed by Dr. Owen Lovejoy of
Kent State University. In his theory, the stimulus for  bipedalism  was  the
pairing off of male and female hominids into monogamous  couples.  The  male
began to provide food to the female and babies. When hominids developed this
new strategy, it allowed females to give birth more frequently and males  to
gain exclusive sexual access to a female, which allowed successful pairs  to
pass their genes on to a large number of offspring. What does sex have to do
with how you walk? Well, with this new lifestyle, the male needed  to  carry
large amounts of food back to the female and children. To do this, he needed
to walk upright and free his arms for carrying.

     Dr. White believes "the Lovejoy model is the best available model."  If
Dr. Lovejoy's theory is true, it may reveal how Wookiees  developed  bipedal
strides. While we don't see much of the Wookiees' lifestyle in  the  movies,
key information is provided  in  the  1978  Star  Wars  Holiday  Special,  a
two-hour TV show that is so awful it's fascinating. Yet  the  show  provides
exactly the information we need. In this show,  Chewbacca  visits  Kashyyyk,
returning to the home where his wife Malla and son Lumpy live. And so we see
the monogamous lifestyle that  may  offer  a  possible  explanation  of  the
Wookiees' biped gait. My guess is that plenty of males would be  willing  to
try walking upright on a tree branch if it meant they could have  sex  on  a
regular basis.



     JUST BECAUSE IT GOES "HO HO HO" DOESN'T MEAN IT'S SANTA


     The award for most disgusting alien would have to go to Jabba the Hutt.
Over sixteen feet long, with a bloated sluglike body,  stubby  arms,  and  a
head like a giant pimple,  Jabba  slithers  his  way  through  the  galactic
underworld , with his home base a great palace on Tatooine. According to the
Star Wars Encyclopedia, Jabba secretes mucus and  sweat  through  his  skin,
making him slimy and slippery to catch by enemies.  "His  high  exaltedness"
enjoys snacking on marine life, which he keeps in a  small  aquarium  beside
the dais in his palace's throne room. This suggests Jabba's  native  habitat
may be near the water. Although terrestrial slugs are only a few inches long
at most, they offer the closest comparison we have to Jabba.

     Slugs have soft, slimy bodies and tend to be  nocturnal.  While  common
slugs eat fungi and decaying leaves, some slugs are carnivorous, like Jabba,
eating snails and earthworms. Slugs are hermaphrodites, containing both male
and female sexual organs. The Encyclopedia tells us Jabba is  the  some.  We
should, in fact, call Jabba it, but that seems strange, so  let's  go  along
with the Encyclopedia and call Jabba him. A slug can reproduce by taking  on
the male role and injecting sperm into another, or by simply  combining  its
own sperm and eggs, in essence having sex with itself.

     Jabba may have both of these options as well, which  makes  one  wonder
why he would be attracted to the scantily clad  Leia.  Dr.  Pickover  points
out, "The chance of Jabba finding a human female alluring is about as  great
as you and I finding a female  squid  alluring."  I  prefer  a  male  iguana
myself.

     The belly of a slug is actually a single, tapered foot. The slug  moves
by generating waves of muscular contraction that ripple down the  foot  from
the tail end to the front end. Also helping the slug along are tiny cilia on
its foot, and a mucous sheet secreted by the front of the foot that provides
a slimy carpet to help the slug glide ahead. This secretion of mucous causes
the slug to lose a great  amount  of  water,  so  all  slugs  need  a  moist
environment to thrive.

     Slugs and snails are both in the class Gastropoda, but snails developed
in areas with irregular moisture, their shells a safe place to withdraw  and
contain their moisture in dry times. They can literally seal  themselves  in
and wait years for rain. Slugs, without a  protective  shell,  developed  in
areas that are moist year-round. To make sure they don't run out  of  water,
they conserve what they have, reabsorbing the water in their urine.  But  if
slugs require moisture, how can  Jabba  survive  on  the  desert  planet  of
Tatooine?

     In neither the special edition of A New Hope nor The Return of the Jedi
do we see Jabba outside. Even as he is ordering Han Solo to his death in the
Sarlacc, he remains below decks in his barge, without a clear  view  of  the
spectacle. I can't believe Jabba would willingly miss  seeing  Han's  death.
Jabba must need to remain in darkness most of the time, sheltered  from  the
sun, the heat, and the dry air. Jabba's preference for the dark  goes  along
with a slug's nocturnal lifestyle. Jabba's slit-shaped  pupils  support  the
theory that Hutts are naturally nocturnal. Both his barge and his palace are
kept dark, and he may have humidifiers of some kind keeping the air humid.

     Of course such a method would be extremely costly on  a  desert  planet
where water is scarce. But he is Jabba the Hutt. And Tatooine, isolated  and
unwatched , may offer a very comfortable home for a crime lord.  Jabba  does
seem able to get around, at least in a minimal way. In A New  Hope,  we  see
him in the Millennium Falcon's docking bay, which certainly is not  equipped
with any special humidifiers. Here, Jabba's size may give him  an  advantage
over terrestrial slugs.

     A large slug will dry out more slowly than a small slug. So Jabba could
survive short periods of low humidity without any problems.  The  comparison
to a slug does suggest several ways in which you might cope with a Hutt,  if
you find yourself face to face with one and don't have a chain  to  strangle
him with. First of all, don't try to grab him, because the slime  will  help
him slip away. And if you do manage to get hold of him,  the  Hutt  probably
has another trick up his sleeve.

     Several kinds of land slugs have the ability  to  break  off  the  back
portion of their foot. This  portion  twitches  violently,  distracting  the
enemy, while the rest of the slug slides away. In A New  Hope,  Jabba  seems
shocked when Han jumps onto his back. I wonder if  he  was  nearly  startled
into breaking his body apart. To kill a Hutt, you could always leave him  in
the desert to dry out. If you want to speed up the process, you can irritate
his skin. Just as getting an irritating speck of dust in your eye makes your
eye water, getting some irritating material on the skin of a slug  makes  it
secrete huge amounts of slime. Spreading ashes or salt over the ground where
a slug must travel works very well. The overproduction of slime  dehydrates,
exhausts, and finally kills the slug.

     This could have saved Han, Leia, and Luke lots of trouble. Is it likely
that an alien would look like a slug? The fossil record  reveals  that  from
more   primitive   forms,   land-dwelling,   carnivorous   slugs   developed
independently  several  times   on   Earth.   This   suggests   that   these
characteristics are fairly useful and efficient, and  might  possibly  arise
again on another planet. So when you head out on that  space  vacation,  you
may want to take a bucket of ash with you. And keep an eye on the right side
of the Hutt's head. The slug keeps its male reproductory organ there.



     SLUGFEST


     One of the most surprising aliens, and one of  the  most  difficult  to
understand, is the space slug that lives inside one of the  Hoth  asteroids.
The slug is hidden inside a cave or tunnel in the rock, and Han  unknowingly
lands the Millennium Falcon inside it. The slug  seems  to  use  a  strategy
similar to the Sarlacc on Tatooine, or the terrestrial ant lion or stargazer
fish. The slug stays put with its mouth open, waiting for prey to fall in or
come close enough to be grabbed.

     The stargazer fish buries itself tail first in the sand,  so  only  its
eyes and mouth are visible-and only visible if you know what  to  look  for.
When prey swim by, it gulps them down. Many terrestrial organisms have  such
lifestyles, which seems to make the space slug fairly believable. And  since
we've discussed organisms that live deep underground on Earth, surviving  on
only rock and water, this suggests a narrow  possibility  that  an  organism
could find sufficient nutrition on an asteroid.

     Some asteroids are believed to have a layer  of  permafrost,  and  some
reveal evidence that in the past they  were  heated  enough  so  that  their
interiors melted. While it's extremely unlikely that  any  heat  would  have
lasted long enough to develop life, we could perhaps believe that under some
unusual circumstances , the largest, hottest asteroid could  have  had  some
tiny stirring of life within. Yet the slug is clearly  not  feeding  off  of
water and rock. It is a predator, hiding in wait with sharp  teeth  to  grab
and tear prey apart. This means there must be an  entire  ecosystem  in  the
asteroids .

     There must be creatures on whom the slug normally feeds-  and  I  think
it's fair to assume they aren't spaceships, since a pilot would "have to  be
crazy" to fly into an asteroid field. To support something  as  big  as  the
space slug, these food creatures must be fairly large or  fairly  plentiful.
Even if the slug lies dormant for long periods, it has to feed sometime. Yet
we see no sign of organisms. And if there are microscopic  organisms  living
deep within the rock, the slug cannot be feeding on them, since its mouth is
pointed toward space.  We  might  posit  some  other  microscopic  organisms
somehow floating through space, the giant space slug feeding off them like a
whale feeds off tiny plankton. But then why would the slug have such  fierce
teeth, or the ability to lurch out of its burrow and catch prey?

     The Millennium Falcon seems too small for it to even notice.  Its  prey
must be large and active. Let's put aside for a moment the problem  of  what
it eats. Say there is a  large,  constantly  replenished  supply  of  insane
Corellian space jockeys that fly into the  asteroid  field,  and  have  been
flying into it for the last billion years. Could the space slug live in such
an unfriendly environment? The slug would face a host of problems, including
cold, meteoroids, and high-energy particles. But let's focus  on  just  one:
pressure. Asteroids are too small to hold an atmosphere, so the slug is  not
sheltered in any way from the vacuum of space. Many people believe that  the
lack of pressure in space would  cause  living  creatures  to  explode.  The
reasoning goes like this.

     Our bodies are in a  state  of  hydrostatic  equilibrium  with  Earth's
atmosphere . At sea level, the atmosphere pushes in on us with a pressure of
fifteen pounds on every square inch of our  bodies.  The  fluids  and  gases
inside our bodies exert an equal  pressure  outward  .  Any  change  in  the
pressure causes difficulties. If you are subjected to  pressures  less  than
14.7 pounds per square inch, the body swells and bubbles of gas form in  the
blood. Divers go through some of these stresses when they move  too  quickly
from high-pressure ocean depths to the lower-pressure surface, suffering the
"bends." If you quickly bring a deep-sea fish, which lives naturally at high
pressures, up to the ocean surface, the gases dissolved in their body fluids
will expand and blow the guts out through the mouth. The fish will  explode.
But that's a fish.

     The truth is that, while a pressure of zero pounds per square  inch  is
very unhealthy for humans,  it  won't  make  us  blow  up.  We  will  suffer
violently from the bends, all our internal gases would rush out of our  body
orifices-calling it farting just doesn't cut it-and we'll lose consciousness
in only a few seconds. The proof came in  1971,  when  a  Soviet  spacecraft
underwent accidental depressurization, exposing the three cosmonauts  within
to the vacuum . Their  bodies  did  not  explode  or  become  deformed  with
exposure to the vacuum. Unfortunately, they died from lack of air.

     Dr. Pickover estimates, "You should  have  fifteen  seconds  of  useful
consciousness before you pass out, and several  minutes  would  be  required
before you die." Apes exposed to a vacuum suffered some bleeding from  areas
with blood vessels very close to the surface, such as nasal passages,  eyes,
and lungs, but survived a brief exposure  without  permanent  damage.  Since
humans and apes, which evolved on Earth, can survive the lack of pressure in
a vacuum, it's not unreasonable to imagine that a life-form could develop in
the vacuum and survive there. An organism is, in essence, a contained packet
of liquid and chemicals, like a Ziploc bag filled with water.

     If the skin of  the  packet  is  strong  enough,  it  can  hold  itself
together. Since the slug appears to have no nasal passages  or  eyes,  those
possible sources of danger are eliminated. Another huge threat to  the  slug
remains, however. The slug's mouth  and  throat  are  also  exposed  to  the
vacuum. And if it doesn't have some sort of airlock device to seal  off  its
throat, the slug's entire digestive system would be exposed to  the  vacuum.
If the cells lining the digestive tract are as strong and protective as  the
outer cells of the slug, no problem. But the whole purpose of the  digestive
tract is to absorb nutrients. To do this, cell membranes must be  permeable,
meaning they must be able to pass materials in and out.

     If they are, then the water in the cells will  quickly  evaporate  into
space. Indeed, when Han and the others step out into the slug's throat, it's
moist and misty, suggesting the slug is losing water. Dr. Jakosky points out
that "Any water lost would have to be replaced, presumably by ingesting  new
water, and it's not obvious what the source would be." Their excursion  into
the "cave" raises more problems. Any mist in the slug's open mouth should be
quickly sucked out into space. And since  the  slug's  mouth  is  open,  the
pressure inside the throat would be zero, which would disable Han, Leia, and
Chewie in fifteen seconds, with all their bodily gases rushing out of  them.
That would make for an interesting scene. If the slug had an airlock  device
of some kind in its throat, which would allow food to be passed safely  from
the vacuum outside to a pressurized interior, we might be  able  to  explain
some of this. But when Han flies the ship back out of the slug, there is  no
such barrier.

     Scientists do believe that life may be able to survive  in  space,  but
only hardy bacteria, probably in  their  dormant  spore  form,  buried  deep
within the  rock  of  a  large  meteoroid.  Dr.  Pickover  points  out  that
terrestrial bacteria were found to have survived on a  camera  left  in  the
near-vacuum and extreme temperatures on the Moon for three years, when  they
were retrieved by the crew of Apollo 12. So might a more advanced  life-form
possibly live in the vacuum of space? Dr. Stephens says, "I don't think  the
thing is even remotely feasible." Yet Dr. Jakosky feels  life  may  be  more
varied than we know. "I'd be reluctant to rule it out."



     HOW MANY ALIENS DOES IT TAKE TO START A BAR FIGHT?


     We discussed earlier how unlikely it would  be  for  aliens  from  many
different planets to survive in a single environment, such as the Mos Eisley
cantina. Dr. Pickover raises an additional problem besides the environmental
one. "The senses of aliens could be very different. Communication  would  be
difficult." He points out that every Earthly  species  perceives  the  world
differently . "They can smell what we cannot, they can see what  we  cannot,
they can hear what we cannot."

     Bees, for example, can see ultraviolet light invisible to us, and  dogs
can hear sounds undetectable by us. "If the  organisms  of  the  Earth  were
somehow able to describe their world to you," Dr. Pickover says,  "it  would
probably not be recognizable to you. It's likely that we will never be  able
to fully understand alien ideas, just as we may never be able to  understand
the 'language' of dolphins." Misunderstandings would be  common  unless  one
was in a very close relationship with an alien, like Han's  friendship  with
Chewbacca. Among humans from the some country, misunderstandings  can  arise
easily enough. And among  humans  from  different  countries,  language  and
culture can raise more problems.

     Considering that aliens might see, smell, and  sense  different  things
than we do, it's not surprising that an alien in the cantina  might  dislike
Luke for seemingly no reason. It's a short step from there to violence,  and
before you know it, the barkeeper has more body parts to clean up.



     WHEN THE TEDDY BEARS HAVE THEIR PICNIC


     We discussed the Ewok moon in the  last  chapter,  considering  various
elements of the environment, and found that  it  could  potentially  support
life. Let's now look at the life that  has  evolved  there.  The  Ewoks  are
short, furry creatures that look a lot like teddy bears. They walk  upright,
have short limbs, and short fingers and toes bare of fur. Each hand  has  an
opposable thumb, as on humans , allowing  the  Ewoks  to  use  tools.  Their
fingernails and toenails look like humans' and are kept neatly  trimmed.  In
Return of the Jedi we learn that they  set  traps  for  food,  so  they  are
predators. According to The  Star  Wars  Encyclopedia,  they  are  not  only
hunters but gatherers, which makes them omnivores. The Ewoks live in  tribal
groups, in villages built high up in great trees of the forest.  The  Ewoks'
small size would be a handicap in their development of tools and technology.
It would allow them to wield a tool with only about one-twenty-fifth of  the
energy we could, making it hard to imagine how they might chop  wood,  build
their homes, or kill an animal with one of those spears.

     Their stubby fingers would make fine work  very  difficult.  And  their
short arms make it hard to imagine the Ewoks starting a fire without burning
their noses. But perhaps they're particularly  dexterous  and  patient.  The
terrestrial animals that Ewoks most resemble are koalas, Australian  natives
about thirty inches tall. These short, furry  creatures  have  rounded  ears
that perch on top of their heads like the Ewoks'. The color and  pattern  of
koala fur varies with the individual, also like the Ewoks'. Koalas have long
fingers, including two opposable thumbs on each hand and one on  each  foot.
These allow the koala to hold branches in a powerful, viselike grip.  Koalas
also have long claws to help  them  climb  trees,  and  rough  pads  on  the
underside of their hands and feet to increase their traction while climbing.
Koalas live in loose groups, but they each like to have their  own  tree  to
live in. They are vegetarians, living on eucaplyptus leaves.

     Comparison  to  another  terrestrial  species,  chimpanzees,  is   also
illuminating. Chimps live in groups of fifteen to eighty and build nests  up
in trees, as Ewoks do, sleeping in them at night  to  avoid  predators  like
lions and tigers. While chimps are mainly vegetarians , they will  sometimes
kill baboons or pigs for food. Chimps  climb  trees  using  their  powerful,
grasping hands and feet, each of which has an opposable thumb. They also get
around  by  swinging  with  their  long  arms  from  branch  to  branch.  We
immediately see several  key  differences  between  Ewoks  and  these  other
species. Ewoks lack the characteristic traits of tree-dwelling vertebrates.

     Dr. White points out that  such  animals  have  at  least  one  of  two
qualities: "One, a bunch of sharp claws on their hands and  feet  that  they
cling onto the tree with. Two, a quadrumanous or four-handed anatomy. If you
look at the foot of a primate, it looks like the hand, and  it  can  grasp."
While Ewoks have opposable thumbs on each hand, their fingers are really too
short and fat to use these thumbs to grasp any but the skinniest branch. And
their feet have no opposable digit. It's hard to imagine  them  scaling  the
huge trees that surround them, since their arms  and  legs  could  not  wrap
around them, and their nails could not dig  into  the  bark.  Anthropologist
Michael Seaman finds the Ewoks' body structure unlikely.  "They  don't  look
like they're really adapted for anything."

     We could argue that Ewoks don't naturally live  in  those  huge  trees,
just as humans don't naturally live in apartment buildings.  The  Ewoks  may
have simply decided to move into the trees because it appealed to  them,  or
because it offered them shelter from  ground-dwelling  predators.  And  they
might use stairs and ladders to climb up  there,  rather  than  climbing  up
unaided. Michael Seaman finds this more plausible. "They may have evolved in
a different type of forest or scurrying along the ground." In  a  forest  of
smaller trees, their stubby limbs could be more effective.

     They could put one foot on either side of  the  trunk  and  push  their
bodies up, like we climb a rope. If they did evolve in  a  forest  of  small
trees, though, what happened to it, or why did the Ewoks move to this forest
of giants? Perhaps the Ewoks  simply  multiplied  and  spread  beyond  their
original habitat. Perhaps they were displaced by Imperial forces. Or perhaps
they found the great trees better homes for  more  extensive  ,  elaborately
constructed villages, where they could really put on a great Jedi barbecue.



     THE SMALL, THE BIG, AND THE HAIRY


     To consider the final group of aliens in the chapter, let's  return  to
the planet Tatooine. In Chapter 1, we theorized that  the  planet  may  have
gradually dried over billions of years. How would life adapt to  the  desert
environment? Surviving under such harsh conditions requires  that  organisms
cope with extremes of temperature , survive with little water, and make  the
most of what water they have. On Earth, a wide range of animals  and  plants
have adapted to life in the desert. They have many  mechanisms  for  dealing
with the lack of water, some external, some internal.

     We have no information about what internal mechanisms might be employed
by Tatooine dwellers, but we can deduce a fair amount about how well they're
adapted to a desert environment by  their  external  characteristics.  Small
mammals tend to deal with the heat  by  retreating  to  underground  burrows
during the hottest part of the day. Only a few inches below the ground,  the
temperature can be significantly  cooler.  Since  most  of  these  creatures
cannot pant or sweat to release excess heat, it's critical for  them  to  be
able to escape the worst of the heat through behavior. This solution to  the
heat is limited to small animals, since the larger the animal, the harder it
is to dig an underground burrow of sufficient size.

     On Earth, the Jerboa or desert rat stays in  such  burrows  during  the
day, where the temperature usually reaches no more  than  68  degrees.  When
they come out at night, they move so quickly that they look  almost  like  a
cartoon Roadrunner blur. Their long hind legs allow  them  to  leap  like  a
kangaroo up to 61/2 feet, and their large feet, a bit like  snowshoes,  help
them move quickly over loose, sandy soil.  This  jumping  motion  keeps  the
contact between their feet and the hot sand to a minimum. Another trait they
share with the kangaroo is a long tail that helps them keep  their  balance,
even when they suddenly change direction. These traits allow  them  to  move
quickly with minimal exertion, a  very  valuable  ability  to  have  in  the
desert, where you want to get food and get home before sunup.

     The Jerboa are quite good at functioning on little water. They  extract
all their needed water from the seeds they eat. They're also much better  at
conserving water than humans are. Since they don't pant or  sweat  to  lower
their body temperature, they don't need as much water as we do. They excrete
very little water, 20 percent less than a regular rodent. They also seal  up
their burrows during the day, locking in the moisture, and they  sleep  with
their mouths lying next to stored seed, the moisture in their  breath  going
into the seed to be eaten and recycled later.

     While different  deserts  are  homes  to  different  species  of  small
rodents, they all have these elongated back legs and shortened  front  legs,
suggesting that these are very valuable  characteristics  to  have.  We  see
strikingly similar creatures in Mos Eisley in the special edition of  A  New
Hope. They scatter as Luke and Obi-Wan drive into  the  city.  These  little
Scurriers have short front legs, long hind legs, and long  tails,  and  they
usually run on their two hind legs, just like the Jerboa. While  we  do  see
them out during the day, this may be because their normal rhythms have  been
disrupted by man. Or perhaps daytime is the  best  time  for  scavenging  on
Tatooine , and a quick scurry from one air-conditioned building  to  another
may keep them sufficiently cool.

     Tatooine also has its share  of  larger  species.  Large  animals  take
longer to  heat  up  than  their  smaller  counterparts,  giving  them  more
tolerance to heat. If you put a glass of iced tea and a gallon of  iced  tea
out in the sun, you would expect the glass of tea to grow warm more  quickly
than the gallon. The smaller the object, the more quickly it  will  heat  or
cool. So once an animal is too large to burrow into the ground and must stay
out in the sun, the larger it is, the better.

     The Dewback is a reptile indigenous to Tatooine. We see storm- troopers
riding this large, ungainly, four-legged creature. It has gray-green skin, a
thick muscular tail,  skinny  legs,  and  bird-type  feet,  and  performs  a
hitching waddle through the sand. While reptiles cannot withstand  extremely
hot temperatures, they do  have  several  advantages  over  other  types  of
animals in a desert setting. Their tough, scaly skin keeps water loss  to  a
minimum , and their eggs have leathery  shells  that  keep  them  safe  from
drying out. But desert-dwelling reptiles have a hard time dealing  with  the
heat because they are cold-blooded.  Their  temperature  is  not  internally
regulated,  as  ours  is,  but  simply  rises  or  falls  depending  on  the
environment.  This  makes  controlling  body  temperature  one  of  the  top
priorities of any reptile. Exposed to the sun on  a  hot  desert  day,  most
reptiles' temperatures will rise too high for them to  survive.  No  reptile
can survive a temperature of over 118 degrees.

     My iguana, Igmoe, basking outside on our deck on a sunny 85-degree  New
Hampshire day will begin to pant after an hour or so, struggling to  release
excess heat. One method reptiles have of controlling their body  temperature
is to manipulate how much of their body is exposed to the sun.  To  maximize
heating, they orient their long, cylindrical bodies with one side toward the
sun. To minimize heating, they aim either their heads or  tails  toward  the
sun, exposing as  little  surface  area  as  possible.  Even  then,  though,
temperatures will often rise above the point they can tolerate. To cope with
this, most reptiles are active in the morning and evening  only,  retreating
to rock crevices or burrows at the hottest part of the day.

     Hopefully the stormtroopers don't force the Dewbacks out into  the  sun
at temperatures above what they can tolerate. The Dew- backs  seem  to  cope
reasonably well in the daytime situations where we see them. By manipulating
their orientation to the sun, they can  at  least  minimize  the  heat  they
absorb.

     Another technique for coping with  the  heat  is  used  by  the  agamid
lizards. They have long legs that hold  their  bodies  up  off  the  burning
sands. This offers a small bit of relief. In  addition,  the  agamids,  when
stationary, always keep one foot in the air, constantly  switching  feet  by
turns in a circular cycle, so no one foot will get too  hot.  The  Dewback's
skinny legs are tall enough to keep its underside a foot or  two  above  the
hot sands, so it can avoid that intense heat just like the agamids. I'd like
to think it might also alternate feet, though we don't see  a  Dewback  long
enough to observe this. The Dewback's feet are its  most  troubling  aspect.
They are quite birdlike, with two toes pointing generally forward in a V and
one toe pointing straight back. While the  spread  of  the  toes  will  help
distribute the weight of the Dewback over a large area, making this type  of
foot superior to a hoof, the narrow toes will not be terribly  effective  at
pushing through loose sand.

     The camel, for example, has webbing between its two broad toes,  and  a
foot as big as a plate. The arrangement of the Dewback's  toes  suggests  it
does not normally live in areas of loose sand. Most likely, it lives in more
stony regions of the desert, as many reptiles do. There, its tough bird feet
would serve it well. But on loose sand they could easily get bogged down.  I
wouldn't suggest stormtroopers ride them into the Dune  Sea-or  then  again,
maybe I would. One final interesting characteristic of the  Dewback  is  its
name. As night falls on the desert, the ground cools  rapidly,  cooling  the
air directly above it as well. Since cool air can't hold as much moisture as
warm air, the cool air deposits a thin layer of dew on the ground. What does
that have to do with the Dewback? Well, one terrestrial reptile, the  thorny
devil, uses dew. Its skin cools rapidly as night falls,  triggering  dew  to
condense on its body just as it does on the ground.

     This dew then runs into hundreds of folds in the thorny  devil's  skin,
the folds channeling the droplets of dew to the thorny devil's mouth,  where
it can drink them. The Dewback may have a similar mechanism, dew forming  on
its back and running through the wrinkles and folds in its skin to  a  place
where the Dewback can access it. Another reptile that lives on  Tatooine  is
the Ronto, a longnecked beast of burden that looks like  a  new  species  of
dinosaur. The Ronto has a number of characteristics that suggest it  may  be
well adapted to  desert  conditions.  The  long  neck  of  the  Ronto  is  a
characteristic it shares with a number of  desert  dwellers.  Giraffe-necked
antelopes not only have very long necks that allow them to eat leaves out of
reach of other animals, but they can stand on their hind  legs  as  well  to
reach vegetation even higher up. The Ronto may similarly  use  its  neck  to
reach food, and we see it rear up on its hind legs.

     The camel also has a long neck, as we discussed earlier. The height  of
the camel's  head-a  result  both  of  its  long  neck  and  its  very  long
legs-elevates it above the level of most sandstorms. Sand particles tend  to
be of a rather uniform size. Thus when the wind blows at a certain velocity,
the height that the sand can be lifted is fairly predictable.  Depending  on
the ferocity of the storm, sand may rise from 3 to 61/2 feet off the ground.
Below that height, the air is filled with stinging sand that can invade your
nose and mouth. Visibility is reduced to almost nothing. Above that  height,
the air is almost completely clear. In a sandstorm , a  camel's  head  rises
above the level of the sand, allowing it to  breathe  and  see  with  little
problem.

     The Ronto would share this advantage. The Ronto's legs raise  its  body
higher than the Dewback's, so its stomach is about a Jawa's height  off  the
ground. A hot layer of air tends to form in the  few  feet  just  above  the
desert surface, and the Ronto's legs would help to  elevate  it  above  this
layer. In addition , the Ronto's large round feet resemble those of a camel.
About the size of a serving plate, they  would  help  keep  the  Ronto  from
sinking into the sand. The Ronto's neck is thick and bony, and it has a bony
bulge  behind  its  head.  Different  species  of  dinosaurs  had  odd  bony
structures in the head and neck area that may have served various  purposes.
The protoceratops had a bony growth on the back  of  its  skull  that  looks
rather like the bulge behind the Ronto's head.

     The triceratops had a wide bony frill like a crown protruding from  the
back of its head. By  studying  the  chemical  composition  of  this  frill,
scientists recently discovered that it helped the  dinosaur  radiate  excess
heat. Dr. Reese Barrick, from  the  University  of  North  Carolina,  tested
various sections of the  triceratops's  skeleton  for  levels  of  different
oxygen isotopes. An isotope is simply a different version of  an  element  ,
with either more or less neutrons in its nucleus than  the  element  usually
has. Oxygen normally has eight neutrons in its nucleus.

     But sometimes a heavier oxygen is found with ten neutrons. The  heavier
oxygen tends toward cold locations, while the lighter tends toward warm.  As
the triceratops grew, the bones in colder parts of its body had  more  heavy
oxygen incorporated into them, while bones in  warmer  parts  of  its  light
oxygen incorporated into them. Thus by measuring the levels of the different
oxygen isotopes in various bones, Dr. Barrick could deduce the  temperatures
at different points in the triceratops's body. What he found  was  that  the
frill was warm in the middle and cool on the outside, showing that it helped
radiate heat away. Similarly, desert jackrabbits use  their  large  ears  to
radiate heat, as we discussed in connection with jar jar.

     The jackrabbits' ears have a dense network of blood vessels that  bring
the hot blood near the surface of the skin and allow it to release its  heat
to the environment more quickly. The cool blood then returns to the interior
of the body, cooling  the  rabbit.  Scientists  discovered  signs  that  the
triceratops's frill similarly had a network of blood  vessels  crisscrossing
it.  While  scientists  aren't  as  certain  about  the   purpose   of   the
protoceratops 's bony bulge, one possible explanation for  it--and  for  the
Ronto's oddly shaped head and neck is that the structure  helps  to  radiate
excess heat and keep the animal cool. Another large species on  Tatooine  is
the Bantha, an elephant- sized mount used by the Sand People. While  Banthas
are not native to Tatooine, they appear to function quite well in the desert
heat. Their most striking characteristic is their long, thick fur.

     You might think that fur would be a horrible hindrance in  the  desert,
overheating the Banthas like a  fur  coat.  Yet  fur  insulates  an  animal,
keeping out excess cold or heat. Many desert  animals  have  fur,  from  the
jerboa to the antelope to the camel.  In  the  desert,  the  sun's  heat  is
actually absorbed by the fur  on  the  animal's  back,  preventing  it  from
penetrating deeper into the skin. The  hair  on  a  camel's  back  has  been
measured at 158 degrees, while the body temperature of the  camel  was  only
104. The Bantha's fur would certainly help it cope with the heat. The Bantha
also has a long, furry tail. While we see it dragging along on  the  ground,
it may be capable of significant movement, as most animals' tails  are.  The
Namib ground squirrel fluffs out its tail and holds it up over its head like
a parasol, to shelter itself from the sun.

     Perhaps the Bantha does the same. There's one more nonhumanoid Tatooine
dweller we have  to  discuss.  The  Sarlacc,  according  to  the  Star  Wars
Encyclopedia, is not a native of Tatooine, but  seems  to  function  in  the
desert climate just fine, digging itself into the  ground  and  waiting  for
prey to come. We can't be sure how big the Sarlacc is, but it must be fairly
large to have such a huge appetite.

     While burrowing seems limited to smaller animals on Earth, the  Sarlacc
somehow manages to get its huge bulk into  the  ground.  For  a  terrestrial
model for this kind of behavior, we look to a much smaller animal,  the  ant
lion. Ant lions live in  a  variety  of  climates  and  are  common  in  the
southwest United States. In their larval stage, ant lions have a large head,
spiny jaws, and a bristly body about 1/2 inch long.  Moving  backwards,  the
larval ant lion traces out a circular pattern , spiraling  steadily  inward,
digging deeper and deeper, until it creates a steep, conical pit in the sand
and buries itself at the base of it. All  that  remains  visible  are  long,
curved jaws that lie open waiting for prey. When an unlucky ant comes up  to
the edge of the pit, the sand collapses, and it falls down into the trap.

     The ant-much like Lando Calrissian-finds it can't climb out of the pit.
The sides are angled so they crumble when the victim  tries  to  crawl  out,
which is just what happens when Lando tries to climb out  of  the  Sarlacc's
pit. In the rare event that the prey looks like it  might  escape,  the  ant
lion flicks sand at it, triggering  an  avalanche  that  brings  the  victim
tumbling into its hungry maw. The ant lion snaps its jaws  shut,  injects  a
paralyzing poison and digestive acids into the victim , then sucks  out  its
vital juices. When the ant lion is finished, it flings the  carcass  out  of
the pit with a flick of its head.  Although  the  body  of  the  prey  isn't
digested inside the ant lion for one thousand  years,  as  is  said  of  the
Sarlacc, any juices it has extracted from the prey  do  remain  in  the  ant
lion's body, since it has no method of excreting waste products.

     It's not until  the  ant  lion  transforms  into  its  pupal  stage-the
inactive stage between larva and winged insect-that it can eliminate  waste.
This means that the ant lion must hold all its waste for its  entire  larval
lifetime: three years. And I thought sitting through a movie could be tough.



     DID YOU LEAVE YOUR HEADLIGHTS ON?


     Tatooine has two indigenous humanoid species, the Jawas  and  the  Sand
People, also known as Tusken Raiders. We  have  never  seen  a  Sand  Person
without his protective mask or wrappings, so it's hard to say  whether  they
have specific characteristics favorable for desert  living.  Obviously  they
need artificial aids to survive in the harshest desert conditions,  just  as
we need aids-coats, gloves, and boots-to survive in the winter. If a species
is intelligent enough to use artificial means for survival, they don't  need
to be naturally as well adapted to the environment to survive. So aside from
concluding that the Sand People are intelligent, we can't tell much more.

     The Jawas also remain rather mysterious, swathed in  robes  from  which
their bright eyes pierce. The Jawas' hands appear furred, and the Star  Wars
Encyclopedia calls them "rodentlike," so we might conclude they are a furred
mammal of some kind. They're hanging out among rocks  and  caves  when  they
ambush Artoo. Perhaps they take shelter in caves  during  the  heat  of  the
day--or at least they  may  have  lived  this  way  before  they  had  large
air-conditioned transports for  their  comfort.  The  Jawas'  most  striking
feature is their glowing eyes. While those twin lights do at  first  impress
us as eyes, though, it's not clear that this is truly what they are.

     They may be artificial, a tool, like a coal miner's  light,  to  assist
them in seeing into caves and other dark places. Yet if that is so,  why  do
they keep them on during the day? So perhaps we were right  in  our  initial
impression, and these two glowing  disks  actually  are  their  eyes.  Let's
consider how eyes work. Eyes are sensitive  light-reception  devices.  Light
from the environment enters through the pupil, and that allows us to see our
environment. If the eyes themselves glow like  a  flashlight,  this  intense
outgoing light will interfere with the incoming light, in essence washing it
out.

     Dr. Pickover offers an analogy. "How well could we  hear  if  our  ears
emitted a continuous sound?" Instead, the eyes and lights could be  separate
organs, one to receive light, the other to emit it.  Dozens  of  terrestrial
organisms  emit  light,  including  fireflies,  earthworms,  algae,   fungi,
jellyfish, crustaceans, and fish. Various chemical reactions can  produce  a
bioluminescent glow.  The  most  brilliant  light  from  a  single  creature
probably comes from the Caribbean fire  beetle,  which  has  a  heart-shaped
orange light on its stomach and two yellow-green lights on its shoulders.

     Women even put fire beetles  in  their  hair  as  decorations-an  idea,
perhaps, for George Lucas, in his quest for unusual female  hairstyles.  The
greatest collective light display is put on by male fireflies  in  Thailand,
who gather in rows of trees and put on an impressive  show  of  synchronized
flashing to attract females. The most useful terrestrial animals with  which
to compare the Jawas are deep-sea fish. Two-thirds of all deep-sea fish  are
bioluminescent .

     In the dark depths where a deep-sea fish lives, the lights on  its  own
body may help it attract prey or mates, while the lights on other fish  help
it spot potential mates, recognize predators , and keep close to its school.
These fish have light-producing glands called photophores.  The  photophores
are composed of many tiny tubules, in  which  light-producing  bacteria  are
confined. The bacteria and the fish live in a  symbiotic  relationship,  the
fish providing the bacteria a tasty enzyme to  eat,  the  bacteria,  in  the
chemical reaction that occurs when they eat the enzyme, producing light  for
the fish. Two fish, Anomalops and Photoblepharon, known as  lamplight  fish,
have photophores beneath each eye.

     These photophores can even be rotated in and out of a  bony  socket  on
the fish's face, like headlights on a fancy car, so the fish  can  make  the
lights "blink" by moving them in and out, or the fish can  hide  by  tucking
the lights inside. Muscles can even aim the photophores a bit more ahead, so
they can function more like headlights. At chow time, the fish  gather  with
their  school  and  their  lights  illuminate  the  immediate  surroundings,
allowing fish to see the plankton  they  feed  on.  Looking  at  these  fish
head-on, the photophores look like two glowing eyes.

     If the Jawas did evolve in caves, their lights  could  serve  the  same
function. Even in environments that aren't completely dark,  organisms  find
luminescence an advantage. One of the main uses of luminescence is  to  help
attract the opposite sex. The female annelid fireworm  releases  streams  of
glowing eggs in the ocean. The males are attracted  to  the  eggs,  flash  a
light in response, and release their sperm.

     If the Jawas' lights serve this purpose, they all seem to be constantly
looking for love. Bioluminescence can also serve more devious purposes.  The
females of one species of firefly mimic the flashing pattern  of  another  .
When the males show up ready for action,  the  females,  not  interested  in
mating at all, gobble them up. Similarly, the Jawas might use  their  lights
to lure prey close. The ponyfish has glowing cells along  the  underside  of
its body. When predators below look up at the ponyfish,  the  glowing  cells
help the fish blend in with the light-mottled surface of  the  water  above.
Perhaps  bioluminescent  fungi  grow  inside  the  caves,  and  the   Jawas'
headlights help them blend in with the cave  wall,  camouflaging  them  from
predators.

     The lights might be particularly  useful  in  the  desert.  Before,  we
talked about how the camel's height-and the Ronto's-lifts its head above the
level of sandstorms, allowing it to see and breathe. Jawas, as short as they
are, will be completely immersed in a sandstorm .  Many  short  animals  can
move very quickly to get to shelter in times of need. The Jawas  don't  seem
particularly fleet of foot, though. If the Jawas'  lifestyle  requires  they
travel significant distances from home to find food, they  could  be  caught
out in a sandstorm . In such a case,  their  glowing  eyes  could  serve  as
beacons, helping the Jawas find each other.

     So what good is it to find your friends in a sandstorm  if  you're  all
lost? The camel may shed some light on this. Camels out in the heat  of  day
huddle together. This seems odd; we might expect them to  stand  separately.
But remember that a small animal will gain or lose temperature more  quickly
than  a  large  one.  When  the  camels  group  together,  they  are  making
themselves, in essence, a single, larger organism. So their  temperature  is
affected less by the environment.

     Similarly, Jawas in  the  extreme  heat  and  dehydrating  winds  of  a
sandstorm might want to find each other so they  can  huddle  and  create  a
larger collective organism, perhaps  helping  them  survive  until  the  air
clears.



     AT HOME IN THE JUNDLAND WASTES


     Finally, let's consider the human settlers who live on Tatooine. How do
humans cope in desert environments? Tatooine residents seem to  favor  thick
hooded cloaks and ponchos. Obi-Wan, Qui-Gon, Luke, the Sand People, and even
the Jawas seem to prefer this type of dress. You might think that you'd want
to wear as little clothing as possible in the desert heat (or just enough to
avoid a sunburn). But heavy robes provide the same insulation that  the  fur
of animals does, helping to moderate the temperature beneath  from  extremes
of the environment.

     Bedouin Arabs wear thick robes and head wrappings for the same  reason.
Loose clothing that traps a layer of air beside the body is the  best.  Many
people believe white clothing is much better to wear in the hot  sun,  since
white is better at reflecting heat than black. This  is  only  partly  true.
White does reflect visible light, while black absorbs it. Yet  most  of  the
heat in the desert comes not from visible light  but  from  lower  frequency
infrared light. Infrared light is absorbed as well by white clothing  as  it
is by black. Thus the brown cloak of Obi-Wan and the  brown  cloaks  of  the
Jawas are perfectly suitable to the desert. Even with such clothing, though,
humans must constantly struggle to survive in the desert.

     During sandstorms, the temperature rises and the air becomes very  dry.
A person can lose up to a quart of  moisture  from  his  body  in  an  hour.
Without lots of drinking water,  a  person  can  die  within  a  few  hours,
literally drying into a mummy. And conditions aren't much better  even  when
it's not a sandstorm . Humans cool themselves  by  sweating,  which  quickly
depletes their bodies of water. If Luke Skywalker were abandoned out on  the
desert at twin-sunrise with no protective  clothing  or  shelter,  he  would
sweat away up to twenty-one pints of water before nightfall.

     His body would draw water from his fat,  tissues,  and  eventually  his
blood. As his blood thickened, his body temperature would rise, as if he had
a fever. Blood  circulation  helps  to  cool  blood,  by  bringing  it  just
underneath the skin where it can radiate  heat  away.  Thus  impaired  blood
circulation makes matters even worse. He would not survive a single day.

     Uwe George tells the story  of  a  couple  visiting  the  Sahara.  They
decided to drive their car from a large oasis to a small oasis twenty  miles
away. They arrived safely at the small  oasis,  and  after  a  visit  turned
around to drive back to the large oasis.  They  assumed  their  return  trip
would be as uneventful as the initial one had been, so they didn't bother to
fill their water bottles.

     They also forgot to fill their gas tank. They ran out of gas ten  miles
from the large oasis. The woman decided to wait in the shade beside the  car
while the man went ahead to the large oasis for gas. When the  man  returned
five hours later with the gas, Uwe  George  says,  "She  was  still  sitting
there. But she had perished of thirst."

     Hopefully Luke keeps his speeder stocked with water at  all  times,  in
case of such a situation. The desert is not friendly  to  machines,  either.
Sand mires cars in dunes and chokes up  car  engines.  While  we're  on  the
subject of the speeder, I can't imagine why one would use an open vehicle to
travel in the desert. Loose sand would irritate ones eyes and  nose,  and  a
sandstorm  would  cause  major  breathing  problems.  How  could  one   live
comfortably in such a place?

     The home of Owen and Beru Lars, where Luke lives,  is  built  into  the
ground. Desert dwellers on Earth have used a similar strategy to create cool
homes. In the Tunisian village of Matmata, over one hundred homes have  been
tunneled into the ground, each with a central courtyard  open  to  the  sky.
Such homes are usually two stories deep, the upper story used  for  storage,
the cooler lower story used for living. Just as animals dig burrows to  keep
cool, humans do the same.

     When you look down from ground level into the circular  courtyard,  you
see numerous doors and windows in the walls, and stairs connecting one level
to the other. The scenes in Owen and Bern's home were actually filmed inside
such a structure, the hotel Sidi Driss in Matmata. Having a courtyard  about
thirty feet below ground level  means  it  will  more  often  be  in  shade,
receiving the direct heat of the sun only when it is  nearly  overhead.  The
courtyard also tends to retain cool night air and keep  the  inside  of  the
house cooler during the day. Thick walls further insulate the  inner  rooms,
creating a home significantly cooler than one built above ground.

     We see those thick walls again in Anakin's home in Mos Espa, helping to
insulate the interior even though it's not  below  ground.  Apparently,  air
conditioning is out of fashion on Tatooine. Star Wars  presents  a  universe
filled with an amazing variety of life, filling every  available  ecological
niche. While scientists remain uncertain about what sort of  alien  life  we
will find, it is sure to include species as bizarre as those we see  in  the
movies, and probably species even more bizarre.

     But visiting "a galaxy far, far away" may give us some small hint about
what may be waiting for us out in our own galaxy.  Aliens  aren't  the  only
strange creatures we meet in Star Wars, though. In the next  chapter,  we'll
discuss an entirely different class of creatures that are not aliens at all,
but artificial life-forms: droids.

     The tall one is almost always worried and unhappy,  believing  disaster
around every corner. The short one is adventurous and determined,  impatient
with his cowardly partner. Anxious and frustrated, the  tall  one  at  times
lashes out, verbally and even physically, kicking the short one or  slapping
him on the head. The short one counters by giving the tall one the raspberry
and even, when their differences become too great, abandoning him. No,  this
is not a dysfunctional couple in family therapy; it is  a  pair  of  robots:
C-3PO and R2-D2.

     When most scientists think of a robot, they think  of  a  sophisticated
artificial  intelligence,  sensors   that   can   detect   the   surrounding
environment, some sort of limbs for interacting with the environment, and  a
method of travelling through that environment. Yet a funny thing happened on
the  trip  through  George  Lucas's  imagination.  In  addition   to   these
characteristics , robots gained personalities, desires, and emotions. Droids
can  be  kind,  cruel,  loyal,  afraid,  disgusted,  excited,  concerned   ,
impatient, embarrassed, and proud. These characteristics cause us to  become
as emotionally attached to the droids in Star Wars as we do to the humans.

     We've met many robots in science fiction movies, but none as  memorable
as R2-D2 and C-3PO. First of all, they are amazing embodiments  of  advanced
technology, able to perform a wide variety of tasks. Artoo has sensors  that
can detect distant signs of life on Tatooine  as  well  as  details  of  his
nearby environment, a hologram projector, and a  very  expressive  nonverbal
voice.

     He functions as a component of Luke's X-wing fighter;  plugs  into  the
Imperial network on the Death Star, reads files  and  overrides  controls  ;
carries a huge amount of information; and thinks creatively to complete  his
missions. Threepio doesn't seem quite as brainy, or at least doesn't like to
admit he can follow Artoo's technical talk. He is conversant in six  million
forms of communication, speaking human and alien languages and communicating
with machines , including the Falcon. Threepio calls Artoo his  counterpart,
which suggests they work together in some  way.  But  it's  not  what  these
droids do that makes them so memorable ; it's who they are.

     Artoo and Threepio have personalities as strong as the  humans  in  the
Star Wars universe. In fact, they seem so much like  living  beings  that  I
find myself unable to call either of them it as I  write  about  them.  Both
Artoo and Threepio have strong ideas, goals, and emotions, and  they  bicker
endlessly, though affectionately, like old friends. We sympathize with them,
just as we do with the human and alien characters, as they go through  their
adventures. Might robots like Artoo  and  Threepio  someday  be  within  our
reach?

     And if they are, are these the  type  of  robots  we'll  be  likely  to
create? Before we talk about robot personalities, intelligence, or emotions,
let's take a look at the basic shape of these future robots.



     WHEELS OR LEGS?


     Artoo normally cruises  along  on  three  small  tread  wheels  like  a
tricycle, which is fine for the polished corridors of the Death  Star.  When
he gets onto rougher terrain, like the  swamps  of  Dagobah  or  the  stairs
leading into the Mos Eisley cantina, he has to bring his two back wheels  up
alongside his body and use them as stubby legs. From watching Artoo, one can
tell that these stubby legs don't work terribly well.  They're  very  short,
and lack the joints that help human and animal legs function.

     Obviously Artoo has been designed  to  function  in  a  mainly  indoor,
sophisticated environment , or else to remain stationary,  as  he  is  while
plugged into an X-wing. Most robots today are  stationary,  designed  for  a
specific purpose , and set up in the location where they can accomplish that
purpose, such as on an  assembly  line.  Those  that  require  mobility  are
usually built with wheels. A number of hospitals now use wheeled  robots  to
deliver lab  specimens,  surgical  supplies,  medical  records,  and  meals.
Wheeled robots are simple to make, energy efficient, and can easily navigate
interior environments where floors are smooth. Even some robots designed for
outdoor use have been made with wheels, such as Sojourner, the wheeled rover
NASA recently sent to Mars.

     While Sojourner's mission was a success , its  mobility  on  the  rocky
surface of Mars was limited. For movement on uneven, outdoor  surfaces,  you
might think we'd want to create two-legged humanoid robots such as Threepio.
After all, we have two legs, and we do a pretty good job of getting  around.
Yet of the robots currently in outdoor use  to  clean  up  hazardous  -waste
sites, dispose of bombs,  or  put  out  fires,  none  are  bipedal.  Why?  A
two-legged gait requires a lot of coordination.

     As you walk on two legs, your body must shift  slightly  from  side  to
side so that your center of gravity is more nearly over the supporting  leg.
Sixty percent of human bodyweight is  above  the  hips,  so  balancing  this
top-heavy structure is not easy. You must also learn how to use the  muscles
in your hips, thighs, knees, calves, and ankles to move one leg forward  and
hold the other stiff. Walking uses more than thirty muscles in each leg  and
yet more muscles in the trunk.

     So it actually is quite a challenge to walk and chew gum  at  the  same
time. In designing robots, scientists find it difficult even to artificially
duplicate a bipedal stance. Simply standing still and  balancing  your  body
isn't as easy as you might think. Stand up right now and notice what's going
on in your body (this is the exercise portion of the book). Your leg muscles
will make tiny adjustments as your torso moves slightly forward or back;  in
fact, you'll find it impossible to completely relax  your  leg  muscles  and
remain upright . (You can sit down now.)

     The two-legged stance is inherently unstable. While four legs provide a
much more stable stance-ask any table-walking on four legs still requires  a
shift from side to side in the center of gravity. Five legs are the  minimum
allowing a stable gait. A five-legged robot can have one leg in the air  and
still remain stable without shifting its center of gravity. This  makes  the
coordination  issues  much  less  complex  and  the  gait  much  easier   to
artificially duplicate.

     Of course, if a robot has five legs and can only lift one  at  a  time,
it's not going to be terribly speedy. Scientists have  found  that  modeling
robots after insects, with six legs, provides a stable stance and gait,  and
allows the robots to lift three legs at a time.  Insect-modeled  robots  can
use a tripod gait, the front and back leg on one side hitting the ground  at
the same time as the middle leg on the opposite side. With three legs on the
ground at any time, both insects and the robots based on them are  extremely
stable.

     Dr. Randall Beer and colleagues at Case Western Reserve University have
built several such robots around 11/2 feet long. Although their first robots
were slow and awkward, the latest models are graceful and  almost  lifelike.
By studying the movements of the cockroach and the neurons triggering  those
movements, the team has  learned  that  a  combination  of  centralized  and
decentralized signals control the cockroach  's  legs.  Centralized  control
coordinates the movements of the legs  and  keeps  the  cockroach  balanced,
while decentralized control allows each leg to act more independently.

     The closer the team makes its robots to actual cockroaches, the  better
the robots have performed. These robots are still not nearly as fast as real
cockroaches, though. We have a long way to go before we match their  agility
and speed. Yet robots modeled after insects can skillfully  navigate  uneven
terrain. They've been used to explore an active volcano in Alaska and  clean
up nuclear power plants. They are being developed for  a  number  of  future
uses, including the exploration of other planets.

     Must all legged robots have six legs, then? Well, founder  of  the  MIT
Leg Laboratory Dr. Marc Raibert and colleagues built a robot with  only  one
leg, the most unstable situation there is. Working with just one leg allowed
Dr. Raibert to focus on issues of balance, rather than worrying about how to
coordinate the movement of different legs. The robot maintains  its  balance
by continuously hopping, just as a person on a pogo stick stays  upright  by
hopping. It can hop in a particular direction or follow a  particular  path.
Its top speed is a little less than 5 miles per hour.

     While scientists don't particularly believe a one-legged robot  is  the
wave of the future, they do believe that a two-legged robot that runs  as  a
human runs, with just one leg hitting the ground at any time, is essentially
the same as a one-legged robot. Using this one-legged success, a  two-legged
robot has indeed been built. With its two  legs  hopping  in  turn,  it  can
maintain its forward/backward balance, propel itself ahead at up to 13 miles
per hour, and even bound up stairs. Unfortunately, the robot cannot maintain
its lateral, or side-to-side balance.

     A rotating boom extending from the center of the lab to the top of  the
robot keeps it laterally stable, constraining it  to  hopping  around  in  a
circle. Robotocists at Honda decided to take a different approach when  they
began their humanoid robot research in 1986. Their  goal  was  to  create  a
robot that could operate in people's homes and interact  with  them.  Rather
than trying to create a biped that ran, they thought maybe they should first
teach it to walk. With detailed studies of the joints in the legs and  feet,
they built robot legs that would have the same range of motion and  ability.
They also explored the many ways that humans sense their state of balance  ,
velocity, and direction, and created similar sensors for their robot.

     They have now  built  three  prototypes,  each  progressively  smaller,
lighter, and more skilled at walking. The latest, P3,  is  about  51/2  feet
tall and 300 pounds. It can walk up and down stairs and transport objects in
its arms. Yet it takes slow, deliberate steps, its speed limited to  just  1
mile per hour. The robot has a blocky, bulky appearance, as if it's made out
of giant Legos, with wide legs and feet that help it maintain balance.

     While it has some ability to maintain its stability on uneven  terrain,
Honda scientists are still working to improve this ability. Although bipedal
robots are proving a challenge to build, they  are  appealing  because  they
could be built to resemble humans, rather than cockroaches or  pogo  sticks,
and so would be easier for us to interact with. C-3PO is obviously  designed
to resemble a human, which makes his job of translating speech and following
the customs of various humanoid races easier. A pogo stick would have a hard
time bowing, shaking hands,  or  communicating  through  body  language  and
gestures.

     While Threepio's form may put humans at ease and  foster  communication
with them, it is not terribly mobile. Threepio is a  bit  better  able  than
Artoo to navigate stairs and uneven terrain, yet his range of motion is more
restricted than a human's. He seems barely  able  to  navigate  stairs,  let
alone rocky or swampy terrain, and out on the sands of Tatooine  his  joints
begin to freeze  up.  Obviously  modeling  Threepio  after  a  man  has  its
disadvantages. Do the advantages outweigh the disadvantages, making this the
best design for Threepio? Threepio's knowledge  of  etiquette  and  protocol
suggests he is meant to function among ambassadors and diplomats.

     In such a rarefied atmosphere, in elegant surroundings, we can  imagine
that Threepio could  get  around  fairly  well,  and  his  golden,  humanoid
appearance would add a touch of class to the  proceedings.  But  translating
and assisting the elite aren't Threepio's only duties, much as he might wish
they  were.  His  stated  specialty,  "human/cyborg  relations,"  is  a  bit
confusing,  since  cyborgs  are  organisms  with  mechanical  or  electronic
components, and the only cyborgs we see in the movies are Darth Vader,  Luke
after he receives his bionic hand, and Lando's assistant, Lobot.

     I think perhaps what Threepio means is human/machine  relations,  since
he can serve as interpreter to the Falcon, to moisture  vaporators  or  load
lifters, telling their owners what is wrong with them. This is the  capacity
in which Luke's Uncle Owen wants Threepio to work, serving as  a  diagnostic
tool  for  machines  and  other  droids.  Three-  pio  seems  to   have   an
unnecessarily sophisticated design for  such  a  purpose.  We  have  similar
devices today, such as computers that diagnose problems in the transmissions
of our cars. These computers are immobile.

     We simply bring the machines to be repaired to them.  If  the  machines
are too big to bring in for repair, the diagnostic computer could be mounted
on a simple transport device. Uncle Owen could put it on his speeder or  use
one of the antigravity devices that seem fairly common.  Perhaps  a  simpler
droid like that is what Owen is looking for, and why he's hesitant to buy  a
fancy droid like Threepio. So while Threepio's design  makes  sense  if  his
primary function is  indeed  translating  for  the  elite  and  making  sure
etiquette and protocol are followed at official functions,  he  would  be  a
rare droid indeed in the galaxy, one of only a handful  designed  and  built
for such a specialized purpose. Other droids specializing in human/  machine
relations and translation would likely be of  a  much  simpler  and  cheaper
design. Droids with other  purposes  would  seem  even  less  likely  to  be
bipedal. Battle droids, for example, designed  as  killing  machines,  would
probably be built in a number of different configurations, depending on  how
they were to be used.

     The only situation in which a humanoid form would really be  useful  is
one in which robots are taking the  place  of  human  soldiers;  they  could
operate the same equipment. If human  soldiers  are  not  used  in  specific
combat situations, droids would have little reason for  looking  human.  For
inner-city guerilla fighting, we could use a spherical droid held aloft with
antigravity, similar in appearance to the baseball -sized remote Luke trains
with in A New Hope, though perhaps bigger to allow for increased laser power
and intelligence. If antigravity  is  not  an  option,  then  insect-modeled
robots would be very fast and flexible.

     Such battle droids could inspire terror in the enemy. They  could  even
have laser-gun turrets on their backs. If we're looking for  an  inexpensive
option, an R2 unit could serve in a number of situations.  Plug  it  into  a
STAP or other antigravity vehicle and you  have  a  formidable  weapon.  For
space battles, it could be inserted into an X-wing or other fighter and  fly
it. It could even operate a . Walker. If computers aren't terribly expensive
to build, then you  don't  even  need  an  R2  unit  to  plug  into  various
accessories.

     Just build an intelligent STAP. It doesn't need  a  humanoid  robot  to
hold onto it and fire its weapons. If we were part of the rebellion, and  we
wanted a droid to help us execute our secret missions, what  type  of  droid
would be the most useful? Princess Leia most likely had to make do with what
was available. What if she'd had her choice of designs? Well, a  droid  that
fits in with  its  surroundings  would  have  a  better  chance  of  evading
detection. But since little attention seems to be paid to droids, this seems
a minor concern. One that can easily navigate rough terrain would be able to
avoid capture  and  reach  remote  rebel  bases.  An  antigravity  droid  or
insect-modeled robot, then, would seem to be the most practical solutions.

     But can you imagine Threepio's head mounted on the hood of  a  speeder,
or Artoo with the six legs of a roachbot?



     THESE TANKS ARE MADE FOR WALKING


     0ne of the most memorable battle scenes in Star Wars takes place on the
planet Hoth, where rebels  attempt  to  defend  themselves  against  massive
walking tanks, called All-Terrain Armored Transports,  or  Walkers.  Walkers
seem to have  two  potential  advantages:  height  to  see  and  shoot  long
distances, and the ability to cross  rough  terrain.  These  two  qualities,
while both valuable, actually work against each other. The top-heavy  design
that gives the Walkers their height advantage would also tend to destabilize
them on uneven terrain. We already know that  four-legged  locomotion,  like
that of the Walkers, is unstable and requires that the "body" of the  Walker
shift back and forth to compensate. The massiveness  of  that  "body"  would
make this a challenge.

     A lower-bodied, six-legged robot seems as if it would  function  better
on rugged terrain. But if the Empire does have the ability to  coordinate  a
shift in the top-heavy Walker's center of gravity with its gait, and  if  an
antigravity tank is for some reason impossible, would this be a useful shape
for a  battle  tank?  Using  the  some  techniques  that  created  one-  and
two-legged running robots, Dr. Raibert has created quadruped robots that run
with different gaits, trotting, pacing, and bounding. Such  robots  are  not
yet laterally stable, though. And they'd provide quite a rough ride for  the
Imperial troops inside. Robotocist Kimura Hiroshi  and  colleagues  built  a
walking quadruped robot that resembles a miniature Walker. Its  four  sturdy
legs move quickly, giving the impression of two people scurrying along,  one
behind the other.

     It, too, is not laterally stable. It moves forward while attached to  a
pipe running  above  it.  Yet  it  can  handle  moderately  uneven  terrain,
stumbling over obstacles but quickly regaining its forward/backward balance.
The most fascinating quadruped design is actually  the  oldest  one,  dating
back to 1968. Ralph Mosher at General Electric built a  four-legged  walking
truck.

     Eleven feet tall, it looked more or less like a  truck  taken  off  its
wheels and placed on four tall legs. Rather than being run by computer, this
one's movement was controlled by a human driver in the cab of  the  "truck."
The truck had four controls, two connected to the driver's hands and two  to
his as to take a step, the control would push  against  the  driver's  hand,
reflecting the pressure of the ground against the truck's "foot." This  gave
the driver the illusion that the  truck  limbs  were  his  limbs,  and  made
control easier. The truck was able to move with  agility,  even  climbing  a
stack of railroad ties. The drawback of the design, though, was that it  had
to keep three legs on the ground at all times for  stability,  and  that  it
could move a leg only a small amount at a time, so that its center  of  mass
remained above the three supporting legs. Because of this, its  speed  never
got much above 5 miles per hour.

     The Walkers also only lift one leg at a  time  and  take  fairly  small
steps. The Star Wars Encyclopedia tells us that Walkers can travel up to  40
miles per hour. I'm not so sure. The oddest idea for a tank was patented  in
1942. The inventor was sure it would catch on,  since  it  would  be  nearly
impossible for an enemy to target and destroy. It was a  one-legged  hopping
tank.



     I, DROID


     Now that we've explored the shapes of the droids, let's look  at  their
intelligence. Unlike current robots or computers, they have the  ability  to
plan and perform extremely complex tasks independently . Artoo  demonstrates
this skill in A New Hope when Princess Leia gives him a  secret  mission  to
complete: to deliver himself and Leia's message  to  Obi-Wan  Kenobi.  Artoo
enters an escape pod and sees himself and Threepio safely to Tatooine.  Once
there, he seeks out a populated area,  and  after  being  bought  by  Luke's
uncle, quickly gathers the information he needs. He lies to  Luke,  claiming
to be owned by Obi-Wan, and so discovers the Jedi's location.

     Then, after discerning Luke's interest in Leia's  message,  claims  the
restraining bolt prevents him from playing the entire message, so Luke  will
remove the bolt. Without the bolt, Artoo is free to pursue his  mission.  He
leaves Luke's home and heads off across the desert toward Ben's  home.  This
sequence of actions requires an advanced intelligence, an  understanding  of
human  nature,  the  ability  to   reason,   and   flexible   planning   and
decision-making abilities. Such qualities are key elements of an  artificial
intelligence, or Al,  a  computer  that  exhibits  the  qualities  of  human
intelligence. Scientists have been working to create an Al for forty  years,
and  although  they  have  not  yet  achieved  this  goal,  they  have  made
substantial progress with several different approaches.

     The rule-based approach focuses on making a computer  an  expert  in  a
particular, narrow subject area. By choosing a  narrow  specialty,  computer
scientists are able to program extensive knowledge about  the  subject  into
the computer. IBM's  Deep  Blue,  which  beat  world  chess  champion  Garry
Kasparov, is one such system. The computer contains all the rules pertaining
to chess and has the ability to  weigh  various  possible  moves  and  their
outcomes to choose the best one. Such systems, however, quickly  break  down
when the computer is presented with a problem outside its area of expertise.

     It can't extrapolate  from  the  knowledge  it's  been  given  or  make
comparisons; it can only follow the rules.  2-1B,  the  medical  droid  that
treats Luke after he's attacked by the Wampa ice creature on Hoth, may be an
example of such a system. It has expertise in a narrow area, but appears  to
have minimal interpersonal skills-like many doctors. Both Artoo and Threepio
appear  to  have  certain  areas  in  which  they  are  "experts,"  such  as
translation  and  piloting  an  X-wing,  but  they  also  exhibit  a   great
flexibility to function usefully in a wide variety of circumstances. So they
can't be exclusively rule-based systems. A second approach  scientists  have
taken is to create an Al that uses case-based reasoning. Rather than blindly
following rules, the  computer  draws  analogies,  comparing  the  situation
confronting it with other situations it knows, determining  which  are  most
similar , and drawing information from the comparisons. For  example,  Artoo
probably knows where human settlements are on Alderaan and a number of other
planets.

     To find human settlements on Tatooine , he could compare the geographic
features of those other settlements with the geographic features he observed
as the escape pod fell toward Tatooine, locating the most likely  areas  for
human habitation. In fact, this seems to be what he does, suggesting that he
has some case-based abilities. Such systems have had some success  ,  though
unless the  comparison  is  straightforward,  the  case-based  systems  have
difficulty determining which comparisons are suitable and which are not.

     To do that, computers need to  have  some  basic  knowledge  about  the
world, what we call common sense. Our common  sense  is  built  from  things
we've learned throughout our lives. While we tend to take  it  for  granted,
this knowledge is very difficult to impart to a  computer.  Both  Artoo  and
Threepio exhibit a great deal of common sense. For example, they  know  that
if Luke is trapped in the garbage masher, he will not suddenly appear beside
the Millennium Falcon. They know that if the two walls of the garbage masher
come together, they will squash and kill Luke. And  they  know  that  humans
prefer to be living than dead, so that Luke will be happy if they  are  able
to stop the garbage masher. All these things may seem  obvious  to  us,  but
they are not obvious to a computer , unless this information is  input  into
it.

     Dr. Douglas Lenat has been programming common  sense  into  a  computer
called CYC, short for encyclopedia. His goal is  to  give  CYC  one  hundred
million pieces of common sense. This  knowledge  will  help  it  draw  valid
comparisons and make decisions more efficiently , eliminating impractical or
undesirable solutions. Thus far,  CYC  has  conducted  much  more  effective
searches for information than standard Internet search engines. For example,
when asked to deliver a photo of "a  strong  and  adventurous  person,"  CYC
delivered a photo with the caption, "a man climbing a rock face."

     CYC recognized that rock climbing is adventurous and requires strength.
A third approach to creating an Al is to build a system that can learn  from
experience. If we can give a computer the ability to perceive events  around
it and learn from those events, then potentially the  computer  can  develop
intelligence  just  as  a  baby  does.  To  create  such  learning  systems,
scientists build neural networks, systems designed to mimic, in a crude way,
the structure of the human brain. Regular computers are governed by a single
complex central processor. Yet the brain has no central control.  The  brain
consists of roughly one hundred billion nerve cells, or neurons,  with  each
neuron connected to ten thousand others. In imitation of the  brain,  neural
networks consist of many simple processors without any centralized governing
program.

     These simple processors are connected to each other  similarly  to  the
way neurons are connected to each other in the brain. Scientists believe the
massive number of connections between neurons gives the brain its ability to
process one thousand trillion pieces of information  simultaneously  .  This
huge degree of interconnectedness, called parallelism, allows many different
signals to travel from one place to another at the same time.  Steve  Grand,
Chief Technology  Officer  of  Cyberlife  Technology  and  Director  of  the
Cyberlife  Institute,  which  is  devoted  to  the  creation   of   advanced
intelligent artificial  life-forms,  believes  parallelism  is  key  to  the
development of artificial intelligence .  "Brains  are  really  machines  in
which many  things  happen  simultaneously.  Only  such  massively  parallel
systems are capable of being intelligent."

     So far, neural networks are nowhere near as complex or extensive as the
brain-they have only one-fiftieth the brain power of a  cockroach-yet  in  a
basic way they do reproduce the decentralized  structure  of  the  brain.  A
neural network  works  like  this.  Computer  scientists  input  a  specific
stimulus on the input side of  the  network.  The  stimulus  is  transmitted
through these connections to other processors, and a signal  is  emitted  on
the output side of the network. By "training" the  network,  scientists  can
make it emit the desired output. But how do we train a neural network?

     The connections are the key to the network, rather than the  individual
processors. These connections can  be  strengthened  or  weakened,  and  the
process of changing their strengths reproduces, in a  rudimentary  way,  the
learning process in the  brain.  Neurons  in  the  brain  remember  previous
signals that have passed through them, and which other neurons those signals
have come from. Based on this previous experience, neurons give more  weight
to signals from other specific neurons. Those connections are  strengthened,
while others are weakened. This process is going on, for example,  when  you
are learning to play the piano or multiply and divide.  Pathways  are  being
established  in  the  brain,  making  these  tasks  easier  with   practice.
Scientists train the network by adjusting the strength of  its  connections,
creating the appropriate pathways that produce the desired result.

     These adjustments mimic a basic level of learning, yet the network uses
no  logic  at  all.  Even  though  neural  networks  aren't   yet   terribly
sophisticated, they have the ability to master processes that aren't  easily
programmed . For example, they  can  recognize  complex  patterns,  a  skill
called pattern matching.  Neural  nets  are  now  being  used  to  recognize
patterns and predict trends in the stock market. Scientists are also testing
them as components in electronic eyes.

     In the future, they might  help  computers  recognize  people's  faces.
Right now a computer can recognize a person's face only when it  displays  a
constant neutral expression and is shown in a full-face,  straight-on  shot.
Strong pattern-matching abilities could allow  a  neural  net  to  recognize
Leia's face under various lighting conditions , at  an  angle  or  partially
obscured, when she is smiling or frowning, or even with her hair in  various
exotic configurations.

     Artoo and Threepio certainly have this ability.  Steve  Grand  believes
connectionist techniques used in neural networks are the most promising  for
creating artificial intelligence. "Rule-based systems and case-based systems
have had fifty years to prove themselves and haven't  exactly  lived  up  to
their promise ." Grand judges that Artoo uses neural networks. "Intelligence
of the kind R2-D2 shows is by  nature  an  emergent  phenomenon,"  he  says,
meaning that it arises as a property of a  group  rather  than  of  any  one
member of that group. Grand gives  an  example.  "You,  as  a  distinct  and
unified human being, are an emergent consequence of the interactions of  all
the billions of individual cells that make up your body. There is no  single
cell in which 'you' reside."

     Similarly, the many processors connected in parallel that make  up  the
neural net. Intelligence cannot exist in any single processor. Yet to create
intelligence through many interconnected processors, we need  to  make  them
interact the way neurons do in the brain.

     "The big snag," Grand explains, is that "we have almost no idea how the
brain  works  at  all!"  Since  Artoo  and  Threepio  have  pattern-matching
abilities, we can assume neural nets make up at least part of their systems.
In addition, the Star Wars Encyclopedia says Artoo and Threepio have avoided
the regular memory wipes imposed on droids, which has allowed them to  learn
from experience. The ability to  learn  again  implies  the  involvement  of
neural nets. Our best chance at creating a true artificial intelligence  may
be in combining these three approaches. And the droids seem to do just that.
The most brilliant intelligence, though, will not make a good  robot  unless
it can  sense  its  surroundings,  gathering  information  ,  learning,  and
interacting. Artoo and Threepio can see, hear, and even feel. How  far  away
are we from creating robots with these abilities?



     DO YOU HEAR WHAT I HEAR?


     Threepio and Artoo have a variety of ways to sense  their  world.  They
both seem to see, hear, and have a sense of touch. Both Threepio  and  Artoo
react when they are touched: in The Empire Strikes Back, Threepio turns when
Han touches his shoulder; and in  A  New  Hope,  Artoo  bows  when  Threepio
touches the back of his head. Creating robots with any of these senses poses
a fascinating and difficult problem. We touched briefly on the difficulty of
teaching a robot to recognize a person's face from different angles and with
different expressions .

     That's just one small example of the difficulty of making  robots  that
"see." Certainly we can connect a video camera to a computer. Computers  can
store video input and manipulate it. But teaching them to actually "see" the
images the video contains is a completely different issue. The computer must
separate objects from the background and be able to recognize these  objects
and their significance . Simply distinguishing where  one  object  ends  and
another begins is difficult. Often the only clues are a change in  color  or
texture . Objects that move create even more problems.

     In the company of people, the computer must not  only  recognize  faces
under different circumstances, but must recognize bodies in  many  different
positions, carrying out a variety of actions.  And  it  must  recognize  the
significance of those actions. For example, Threepio needs to know that when
Han raises his index finger straight up in front of him, as he does  in  The
Empire Strikes Back, it means "Wait a minute," or possibly  "Threepio,  shut
up."  Computers  have  been   programmed   to   recognize   a   variety   of
two-dimensional shapes, such as letters of the alphabet  or  photographs  of
human faces displaying neutral expressions. It's  more  difficult  to  teach
computers to recognize three-dimensional objects , since they might see them
from a variety of angles.

     Some factory robots have basic three-dimensional recognition abilities.
For example, they can tell that an object with four legs, a flat  horizontal
surface on top of those legs, and a flat vertical surface  protruding  above
that, is probably a  chair.  Recently,  two  German  scientists,  Dr.  Ernst
Dickmanns and Dr.  Volker  Graefe,  built  a  computer-controlled  car.  The
computer can "see" moving objects well enough to  drive  on  roads  with  or
without lane markings, avoid other traffic, and travel at up to sixty  miles
per hour.

     Still, its ability to recognize objects is limited to a certain area of
specialty. It will be some time before we have robots as visually capable as
humans, or as Artoo or Threepio. As hard as it is to create a robot that can
see, it's equally hard to create one that can hear. Hearing plays a critical
role in the functioning of both Threepio and Artoo. They must understand the
orders of their human owners. But can a computer understand our speech? This
is actually a much more complicated task than you might think, because human
speech is not at all uniform.

     While Artoo might be programmed to enunciate his  whistles  and  clicks
clearly and distinctly, and to  always  use  proper  robot  grammar,  humans
aren't so easily programmed. The problems associated with teaching computers
to hear fall into two general categories:  sound  and  meaning.  First,  the
computer must accurately identify the sounds being made. Not an easy  thing,
since English has over ten thousand possible syllables. Often we don't  even
pronounce every syllable.

     And of those syllables we do pronounce, we don't each generate the same
exact sound. Different people pronounce words  differently.  Sometimes  even
the same person pronounces the same word differently. Princess Leia seems to
like using a British accent in some situations and  an  American  accent  in
others. Once the  syllables  have  been  identified,  the  computer  has  to
separate  them  into  words.  If  each  word  were  spoken  separately   and
distinctly, this wouldn't be too difficult.

     But we tend to run our words and sentences together. In fact, some Star
Wars dialogue approaches light speed, with no pauses to indicate punctuation
. My nominee for fastest line comes in A New Hope from  Luke,  who  delivers
the entire sentence as a single word, without a breath: "You know  with  his
howling and your blasting everything  in  sight  it's  a  wonder  the  whole
station doesn't know we're here."

     If the computer is able to successfully separate the syllables into the
correct words (perhaps Artoo and  Threepio  could  consult  the  script  for
assistance), it still needs to understand  the  meaning  behind  the  words.
Human beings often misunderstand each other. How can robots do  any  better?
This task is far  from  straightforward  .  Each  person  expresses  himself
slightly differently; the meaning of a word often depends  on  its  context;
and a person's tone can completely change his meaning, for example  changing
a sentence from a statement to a question. Artoo and Threepio need  to  deal
with all of these issues and to have sophisticated artificial  intelligences
in order to understand their human  companions.  At  this  point,  computers
remain extremely limited in any understanding of speech.

     They have, however, made progress in recognizing speech. In  the  early
days of speech-recognition systems, they had to be taught to recognize  each
speaker separately, and each word had to be spoken  with  a  distinct  pause
between. Now, although systems still improve as they gain familiarity with a
speaker, such systems can recognize, to a  limited  extent,  the  speech  of
strangers. If a person speaks at a normal speed, these systems can recognize
a limited one-thousand-word vocabulary. If the speaker separates  his  words
with brief pauses, the systems can recognize up to sixty thousand  different
words. Such systems are used by the  handicapped  to  operate  devices  with
spoken commands , and by lab technicians who can speak their observations as
they look into a microscope.

     They're even incorporated into certain cell phones: just speak the name
of the person you want to call and  the  phone  dials  for  you.  Threepio's
speech recognition goes far beyond the English  language  ,  though.  As  he
likes to remind us, he knows six million forms  of  communication,  and  can
translate between them, such as between Artoo's robot language and  English.
A new software system  ,  Verbmobil,  is  being  developed  to  serve  as  a
translator of German or  Japanese  into  English.  We  might  consider  this
Threepio's great-great-great-great-grandfather. Verbmobil's advanced speech-
recognition system makes a best guess for each word you speak,  checks  this
information against the spoken word's stress and pitch,  and  then  analyzes
the results in two different ways.

     Deep analysis pulls out grammatically  correct  strings  of  words  and
retrieves their meaning from a dictionary of such strings. Shallow  analysis
picks out words or phrases that  have  appeared  earlier  and  compares  the
earlier context to the current one. Verbmobil then looks at all the possible
things you might have said: 1. May the force be with you. 2. May  the  fours
be with you. 3. May the fours bee with you. 4. May the fourth, be with   you.  
5.  May the force be with ewe. 6. May the force be with Hugh. 7.   May   the 
force b with u.  8.  May  the force be with 9. May the force be   with  thew. 
9. May the foreseeable. 10. Mae LaForsby with Hugh? and picks the most likely.

     Hopefully  it's  the  right  one.  You  might  think  with  all   these
capabilities that Verbmobil will soon be  taking  over  translation  at  the
United Nations. Unfortunately , so far it's only being programmed  with  the
limited  vocabulary  needed  to   translate   conversations   about   making
appointments. Shall we meet at 2 P.M. for a secret attack on the Death Star?
After  deciding  what  you  most  likely  said,  Verbmobil  translates  your
statement into an equivalent in Japanese or German.

     This of course does not mean Verbmobil understands what  was  said,  or
its translation. It simply knows which phrases  are  equivalent  to  others.
Verbmobil then articulates the translation with a speech synthesizer . While
Threepio's  voice  sounds  quite  human,  current   electroacoustic   speech
synthesizers are less successful at mimicking the intonation and  rhythm  of
human speech.

     Their speech tends to be slow and monotonous, with an electronic twang.
On a basic level, it's hard enough to  tell  a  computer  how  to  pronounce
words.  Many  words  that  are  spelled  similarly  are   pronounced   quite
differently, such as have and gave, through  and  cough.  A  letter  is  not
always pronounced the same way. So a simple series  of  pronunciation  rules
will not be sufficient. In addition to general rules, the computer  needs  a
pronunciation dictionary to pronounce each word correctly. We have computers
now that have this information and can pronounce words quite accurately. But
that's not enough to  make  the  computer's  speech  sound  human,  or  even
natural. Our speech varies in pitch, volume, speed, and stress.  Programming
in all these different qualities, so that the speech  generated  will  sound
human, would be impossibly complex.

     One promising approach that might allow scientists to avoid some of the
difficulties of programming in all these various factors is  to  use  neural
networks to generate natural computer  speech.  As  we  discussed  above,  a
neural network can be "trained" without any overall governing  program,  and
it is particularly suited to recognize complex patterns, such  as  those  in
speech. A few years ago, Dr. Terrence  Sejnowski  and  colleagues  at  Johns
Hopkins University created NETtalk, a neural network  designed  to  generate
speech. NETtalk was given a passage to practice reading over and over again,
and was told how each word should be pronounced.

     The network began  generating  unintelligible  sounds,  then  developed
recognizable baby-type talk, and within a few hours of training  learned  to
pronounce 92 percent of the words in the passage  accurately.  With  current
improvements  in  hardware,  it's  estimated  that   such   training   could
potentially occur in only a few seconds. We might  then  imagine  Threepio's
speech generator, before it was installed, undergoing  similar  though  much
more extensive training,  learning  how  to  pronounce  a  wide  variety  of
sentences and phrases in six million different languages.

     I wonder if Anakin did that. In the event that Threepio needs to  speak
a phrase outside his training, he might then  use  case-based  reasoning  to
find a comparable phrase, and base his stress and intonation on  that.  What
is apparent in listening to Threepio is that  he  is  not  just  pronouncing
words; he is speaking, with intelligence, will,  and  understanding  .  This
means he combines speech recognition and speech generation  systems  with  a
sophisticated artificial intelligence . And Threepio has yet another quality
to his speech: emotion.

     Threepio's speech is imbued with emotion, from disgust to  arrogance  ,
fear to joy. Scientists are currently studying how emotions affect  the  way
we speak. This can vary  significantly  depending  on  the  person  and  the
situation. Programmers need to find some way to quantify this  in  order  to
create emotional synthesized speech. To generate such speech, we'd  need  to
program a computer to discern which  emotion  would  be  appropriate  for  a
particular utterance , and to then alter those words in  a  way  that  would
convey the emotion. Choosing an appropriate emotion suggests a  computer  is
simply mimicking or simulating a feeling.

     But the emotion in Three- pio's speech  appears  genuinely  felt.  When
Threepio stumbles onto stormtroopers in Cloud City, he actually stutters  in
fear. But is that possible? Can robots feel emotion?



     DO DROIDS DREAM OF ELECTRIC SHEEP?


     The most amazing thing about R2-D2 and C-3P0 is how  human  they  seem.
They  each  have  strong  personalities,  and  constantly  convey  emotions.
Threepio is a worrier and  a  whiner,  concerned  primarily  about  his  own
well-being-his favorite refrain, "Will this never end?"

     To be fair, he also cares about Artoo, "Master Luke," and  others.  Yet
that affection only comes out in the rare moments when Threepio is in a good
mood. He seems constantly irritated, often venting his emotions by insulting
Artoo, calling him  an  "overweight  glob  of  grease"  and  other  colorful
insults. He is disgusted by Jawas, self-conscious about his appearance  when
his legs are not attached, and generally fastidious. He views his "life"  as
one trial after another, and believes one small misstep  will  lead  to  the
spice mines of Kessel or some other horrible fate.

     He is prone to melodrama; self-absorbed and insensitive to others;  yet
can be quite the kiss-up when necessary, as  when  convincing  Luke's  Uncle
Owen to buy him or when translating for "his  high  exaltedness"  Jabba  the
Hutt. Don't get me wrong; I love Threepio. He's anything but a typical hero.
And as a robot, he's fascinating. I just don't think I'd like to  be  locked
in a trash masher with  him.  Artoo,  even  without  the  ability  to  speak
English, manages to convey a clear personality himself,  and  to  express  a
range of emotions . Artoo is loyal to the humans he  serves,  and  he  cares
about them, for example when he stands out in the cold of Hoth scanning  for
Luke.  He  also  cares  about  his  counterpart  Threepio,  though  Threepio
sometimes irritates him, driving Artoo to call him a "mindless  philosopher"
and to give Threepio the raspberry.

     He doesn't like being alone, as when Threepio  separates  from  him  on
Tatooine, and he's frightened when he comes in contact with the Jawas. Artoo
can be excited, as when he discovers Princess Leia  is  a  prisoner  on  the
Death Star; embarrassed, as when he falls from Luke's X-wing into the swamps
of Dagobah and whistles casually to cover; and he can be stubborn, as he  is
when Yoda tries to take a small flashlight from Luke's camp. Could computers
and robots be given human-type emotions and personalities? And why would  we
want to give them such emotions?

     In science fiction, emotional  computers  and  robots  usually  end  up
wreaking havoc. In 2001: A Space  Odyssey,  the  Hal  9000,  which  has  the
ability to perceive the emotions of others and express his  own,  kills  all
but one of the spacecraft's  crew,  and  expresses  fear  as  the  remaining
astronaut turns him off. In Saturn 3, a robot lusts after Farrah Fawcett and
goes on a killing rampage. In the Star Trek episode "The Ultimate Computer,"
a computer given its creator's personality and emotions fears that  it  will
be turned off. It believes that war games  are  actual  attacks  and  begins
shooting at friendly ships. When finally convinced by Captain Kirk  that  it
has committed murder, the computer feels guilt over its  mistake  and  kills
itself.

     In these cases, and in life, emotion is often perceived as  negative  .
Too much emotion in a person  or  a  robot  can  lead  to  irrationality  or
psychosis. Decisions made out of emotion are considered unwise. Most  people
believe robots should be rational, logical, and  scientific,  unaffected  by
emotion. Yet some scientists argue that while too  much  emotion  can  cause
irrational behavior, so can too little. Let's first look  at  how  decisions
are made in the human brain. We might like to think that  we  weigh  options
logically and unemotionally , but scientists are finding that  this  is  not
true. Researchers have spent a lot of time trying to pinpoint the  different
sections in the brain where abstract thinking and emotional responses occur.

     The neocortex, made up of gray matter, forms the outer layer of the two
large hemispheres of the brain, and is believed to be the location  of  most
thought. The limbic system, the more interior  section  of  the  brain  that
includes the hypothalamus, the hippocampus , the amygdala, and the  anterior
cingulate cortex, is believed to be the location  of  emotion,  memory,  and
attention.

     Yet what scientists are now realizing is that  most  functions  of  the
brain tend to involve both the neocortex and the limbic system,  both  logic
and  emotion.  The  systems  work  in  concert,   intertwined,   information
constantly passing between them. Emotions do not intrude on reason; they are
actually a critical part of  it.  In  a  normal  human,  only  the  simplest
decisions can be made totally  logically.  Dr.  Rosalind  Picard,  associate
professor at the MIT Media Lab and author of Affective  Computing,  explains
that it must be "a short, well-defined decision.

     Given this rule, you get that decision. For example, if I'm picking  up
trash, and I know that a soda can lying sideways on  the  ground  is  trash,
then when I see such a can, I decide to pick it  up."  Computers  are  quite
good at making these kinds  of  decisions.  More  complex  human  decisions,
however, require emotion as well as logic. Yet we expect computers  to  make
these decisions using only logic. Perhaps  computers  have  been  unable  to
reason  intelligently  because  they  are  missing  the  equivalent  of  the
"emotional" part of a brain. After all, if emotions and  desires  served  no
purpose, why would they have evolved in us and in so many animals?

     Recent research reveals that emotions help motivate  us;  help  us  set
priorities; help guide our reasoning , planning, and decision  making;  help
us focus our attention; and help us cope with  adversity.  Evidence  of  the
importance of emotions has been found by Dr.  Antonio  Damasio,  M.  W.  Van
Allen Professor of Neurology at the University of Iowa College  of  Medicine
and author of Descartes' Error. Dr. Damasio  treats  patients  with  frontal
lobe disorders. In these patients, communication between the  neocortex  and
the limbic system is impaired, giving Dr. Damasio an  opportunity  to  study
how humans function when logic and emotion are not intertwined .

     The patients seem extremely logical and intelligent,  yet  unemotional.
As Dr. Damasio says, they seem "to know but not to feel. " You  might  think
such people would act very rationally. And sometimes they  do.  Dr.  Damasio
relates the story of one patient who  drove  to  the  doctor's  office  over
treacherous roads after an  ice  storm.  With  complete  calm,  the  patient
navigated the slick roads, utilizing the  appropriate  methods  for  dealing
with icy conditions.

     The woman  driving  in  front  of  him  skidded  on  the  ice,  reacted
inappropriately by braking, and spun into a ditch. While most  of  us  would
have reacted to her skid in fear and perhaps hit the brakes  ourselves,  the
patient had no such reaction, continuing sedately on his way, following  the
correct procedures. Here, the patient 's unemotional  state  worked  to  his
advantage, much like we imagine a computer's unemotional state  to  work  to
its advantage. Yet in actuality  this  lack  of  emotion  is  more  often  a
hindrance than a help. As emotion declines, so does the power to reason. Dr.
Damasio's logical patients are actually unable to make  rational  decisions.
To make even the simplest decision,  they  consider  each  possible  option,
debating endlessly with themselves about which is best. Dr. Damasio  relates
another story of the same patient.

     The doctor suggested two possible dates for their next appointment, and
the patient then spent nearly a half hour discussing the pros  and  cons  of
each date, covering  every  possible  circumstance,  factor  ,  option,  and
consequence: other appointments, other commitments , the cost  of  gas,  the
weather, and on and on.  The  doctor  finally  cracked  and  picked  a  date
himself. Most of us, after a brief indecision, would choose  an  option.  We
would decide one factor outweighed  the  others,  or  if  there  was  little
difference, we would go with a gut feeling that one option was  better  than
the others, or we would choose something at random . We would know that  any
prolonged consideration of this minor issue would be a waste  of  time,  and
embarrassing as well.

     Those negative emotional associations would keep us from  debating  the
issue at such length. Yet those negative associations did not play a part in
the patient's  actions.  In  this  case,  the  patient's  unemotional  state
crippled his ability to make a simple decision. "Even  though  emotions  are
considered quite primitive phenomena ," Steve Grand says, "they are  clearly
a very important  aspect  of  intelligence."  If  a  robot  is  flying  your
spaceship, you certainly don't want it "slamming on the brakes" in  a  panic
when this could create a dangerous condition. Yet you  also  don't  want  it
endlessly debating whether it would be better to visit Obi-Wan  on  Tatooine
first and then go to Coruscant, or vice versa.

     And indecision isn't the only problem created by this lack of emotional
input. People with frontal lobe  disorders  tend  to  repeat  the  same  bad
decisions over and over. Dr. Damasio tested patients with  a  gambling  game
designed by  his  postdoctoral  student,  Antoine  Bechara.  A  patient  was
"loaned" $2,000 of play money and told to lose as little as possible and  to
try to make more. Four decks of cards were laid out on the table. The player
was to turn over one card at a time, and a monetary reward or penalty  would
result. The players were not told how the rewards or penalties were decided.

     Two of the decks  provided  rewards  of  $100  interspersed  with  high
penalties of as much as $1,250. The other two decks provided  rewards  of  $
50, interspersed with much lower penalties, no higher  than  $100.  "Normal"
players would experiment with all four decks, but then quickly realize  that
the higher- paying  $100  decks  were  too  dangerous,  carrying  them  near
bankruptcy . They would then stick to the $50 low-risk decks,  turning  many
more cards in these decks. Players with frontal lobe disorders  turned  many
more cards in the "dangerous" $100 decks. With the game only  halfway  over,
they would often have lost all their money and need to borrow more.

     Yet even after borrowing more, they persisted in their previous pattern
of behavior. The negative outcome did not deter them. We would associate the
dangerous decks with bad feelings and the safer decks  with  good  feelings,
and so we would be drawn back to the safer decks. In addition,  most  of  us
would feel shame over making a bad decision, which would focus our attention
on avoiding a repetition of the mistake. The patients don't  make  emotional
associations with each deck, and they decision. Thus, they  aren't  deterred
from repeating that bad decision. This causes  problems  not  only  in  card
games but in life. The patients repeat the  same  mistakes  there  as  well,
losing money in poor investments, starting up ill-conceived new businesses ,
marrying unsuitable mates, and more.

     Dr. Damasio concludes that feelings are "an integral component  of  the
machinery of reason." One additional problem has been  documented  in  those
with frontal lobe disorders: the inability to  remain  focused  on  a  goal.
While most of  us  set  a  hierarchy  of  priorities  and  attach  different
emotional urgencies to different tasks, Dr. Damasio's patients are unable to
do so. Another patient, Elliot, found that he could not keep  focused  on  a
single task or goal. If Elliot was given a pile of  documents  to  sort,  he
could easily become involved  in  reading  one  and  spend  hours  on  that,
distracted from his task. One then can argue that computers without emotions
are prone to  the  same  problems.  Indeed,  artificial  intelligences  have
difficulty focusing and setting priorities. They also tend to make the  same
decisions over and over, whether those decisions lead to  good  outcomes  or
not. And they are not good at coming to those decisions.  Just  like  people
with frontal lobe disorders, they can become overwhelmed by  the  number  of
possible options and waste time in  an  exhaustive  consideration  of  every
factor.

     For example, in A New Hope, Artoo must decide whether to stay at Luke's
house or to seek out Obi-Wan. Yet there are more options  than  this.  Artoo
can stay at Luke's house and tell the truth about his secret  mission  ;  he
can stay at Luke's and attempt to send a message to Obi-Wan; he  could  stay
at Luke's, forget about his secret mission, and take an oil bath;  he  could
leave for Obi-Wan's at night; he could wait until morning to leave; he could
have Threepio: load him into a speeder to reach Obi-Wan's faster. And on and
... on. While humans might instinctively dismiss fifty out of sixty options,
computers have  a  difficult  time  duplicating  this  type  of  elimination
process. Dr. Picard says, "They can't feel what's most important. That's one
of their biggest failings. Computers just don't get it."

     Dr. Picard believes  that  emotions  could  remedy  some  of  the  most
striking failures of current computers. Emotions could  potentially  aid  in
the decision-making process, associating certain options with  good  or  bad
"gut" feelings, and giving the computer a sense of the importance of various
factors. Emotions could help computers realize certain actions or  decisions
lead to negative results , and avoid repeating those mistakes in the future.
Emotions  could  help  robots  set  priorities,  create  motivations,   make
decisions , focus their  attention,  and  communicate  more  helpfully  with
humans. This last benefit, which relates to one of Threepio's  main  duties,
explains why Threepio's creators would have wanted to provide him with  some
emotional ability.

     Both Threepio and Artoo seem able to set priorities, remain focused and
motivated, make decisions, and  interact  rather  effectively  with  humans,
which suggests that they do have emotions. If we did want to give a computer
or robot emotions, exactly what would we need to  do?  Dr.  Picard  proposes
that computers should be given the ability to recognize, express,  and  even
feel emotions.

     Let's take these one at a time. First, we'd need to give the robot  the
ability to sense the emotions of others.



     WHY HAN AND THREEPIO WILL NEVER BE FRIENDS


     If a robot can recognize our emotions, it can use that  information  to
guide its decisions and behaviors, making it more useful to us. The  ability
to recognize emotions would tell a robot what is important to  us,  what  is
irrelevant, what actions or data satisfy us, and what actions or data  leave
us dissatisfied. If my Microsoft Word program could  read  my  emotions,  it
could tell when its "help" function has failed to help me and  I'm  bursting
with frustration- which happens just about  every  time  I  use  the  "help"
function. In such  a  case,  it  could  adjust  its  behavior,  offering  me
additional options or simpler instructions. If  it  found  that  I  remained
frustrated even with these additional options, a simple "I'm sorry"  message
would be nice.

     How can we teach computers to detect our emotions? We  reveal  emotions
in a number of ways:  visually,  through  our  expressions  ,  posture,  and
gestures; aurally, through the inflection of our voices; and through various
bodily processes, such as  heart  rate,  temperature,  and  blood  pressure.
Earlier we discussed how difficult it  is  to  make  a  computer  understand
visual input. If we are successful at teaching our droid to "see,"  then  we
might have it study the human face for patterns that correspond to different
expressions. Facial expressions tend to reveal whether we feel positively or
negatively about something. In addition, researchers have connected  certain
facial muscles and movements with specific emotions, so we could potentially
program such information into our droid.

     Systems are now being developed to distinguish a smile from a frown, or
to track eyebrow movements  and  equate  these  with  emotions.  Yet  people
express emotions differently. Luke expresses his disappointment at not being
allowed to go to the academy by hanging his head  and  frowning,  while  Ben
expresses his disappointment at Luke's insistence  on  leaving  Dagobah  for
Bespin by simply closing his mouth. These expressions can vary depending  on
age, sex, the culture one is raised in, and the specific situation. To  make
life even more complicated, sometimes people hide or  fake  emotions  .  For
example, on Cloud City Lando hides the extent of his anger at  Darth  Vader,
so that his plans to double-cross  Vader  will  have  a  greater  chance  of
success.

     To make matters more difficult, emotions vary in  intensity  and  often
mix with each other to create unique, unnameable emotional states.  A  robot
with diplomatic duties like Threepio would need  to  be  able  to  recognize
different emotions not only in humans,  but  also  in  a  variety  of  alien
species, each of which would  have  its  own  ways  of  expressing  emotion.
Wookiees, for example, have rather inexpressive  faces  yet  reveal  emotion
through voice and body language .

     If you've ever had a pet, you've gone through the process  of  learning
to "read" that animal's emotions. I swear I can tell exactly what my  iguana
is thinking, but it took me several years to develop that ability.  Threepio
would need this skill  six  million  times  over.  He  even  seems  able  to
recognize emotions in other robots . He knows that Artoo is upset when  Luke
is missing on Hoth. Taking all this into consideration, we can see it  would
be quite difficult to give robots the ability to detect emotions. One way to
make this task more manageable would be to have the robot focus on  learning
the emotional states of just one person, its owner.

     This would make it much easier for the robot to learn which expressions
correspond with which emotional states. Just as we're best  able  to  "read"
the emotions of those closest to us, so would droids. Dr. Picard notes  that
when Threepio is not engaged in conversation, he often looks at  Luke,  then
looks at whatever has Luke's attention , then looks back at Luke.  "Threepio
would constantly look at Luke's face, even though  Luke  wasn't  talking  to
him. What was Threepio doing then? It was almost as if he was reading Luke's
face and watching for signs  of  approval  or  disapproval,  seriousness  or
distress." In this way, Threepio could learn which expressions are usual for
Luke in various situations. "You have  to  watch  someone  a  long  time  to
understand what their expressions really mean," Dr. Picard explains.

     A droid could combine its visual input with other information about its
owner,  such  as  habits,  preferences  ,  personal  goals,  reactions   and
expressions recorded in previous situations, in order to  better  judge  its
owner's desires, and so better perform its job.  To  judge  the  desires  of
strangers, a droid might then compare the strangers to its owner to  try  to
understand them. If our robot can also "hear," we might teach  it  to  study
the intonation of our speech to deduce our emotional state. Tone can be very
revealing of emotion. Though my iguana, Igmoe, makes no sounds  himself,  he
can tell when my tone is reassuring, scolding, and even impatient, and as he
detects these various tones, his response varies accordingly. As  with  many
of the qualities we've discussed thus far, programming this information into
a robot is quite complex. If the content of a person's speech is emotionally
neutral (meaning the person is saying something like "Open the door" and not
"Just open the door, you stupid lump!  "),  people  correctly  identify  the
emotions of the speaker only 60 percent of the time.

     So how can we expect robots  to  do  better?  Scientists  studying  how
speech varies with emotion are discovering that many qualities are involved,
including pitch, loudness , inflection, articulation, and  rhythm.  Dr.  Deb
Roy and colleagues at MIT have  created  a  program  that  can  successfully
distinguish between an approving voice and a  disapproving  voice  about  75
percent of the time. With some speakers the emotion is  much  more  reliably
detected than in others, since some people's voices are more expressive than
others. My research assistant, Keith Maxwell, has  a  Joe  Friday-rapid-fire
delivery that reveals very little emotion. Yoda's voice, on the other  hand,
is extremely expressive. For Threepio to  be  an  effective  translator,  he
needs to be able  to  recognize  the  emotion  with  which  someone  speaks,
translate the speaker's  statement  into  another  language,  translate  the
emotion into  the  equivalent  inflection,  rhythm,  and  pitch  in  another
language, and speak the translation with this particular intonation .

     Other sensory data might refine the robot's emotional acuity. While the
voice tends to reveal the intensity of  emotion  and  facial  expression  to
reveal whether the emotion is positive or negative, additional sensors could
help even more. Mood rings popular in the seventies claimed to  reveal  your
mood by changing color with your  body  temperature.  If  Threepio  had  the
ability to measure temperature, heart rate, respiration, blood pressure, and
pupilary dilation, like a sophisticated lie detector, he  could  be  a  more
reliable emotion detector. Combining this data with  information  about  the
individual and the situation could provide a higher degree of accuracy.

     Yet such abilities could also provide conflicting data. Say Threepio is
attempting to deduce Leia's emotional state. Her heart is racing, her  blood
pressure is up, her face is tense and  tightly  controlled.  Threepio  might
conclude that she is very upset, as she is when she comes face to face  with
Darth Vader on Cloud City. Yet she exhibits the same  characteristics  after
kissing Han on the Millennium Falcon. There her  emotional  state  is  quite
different .

     If Star Wars robots did have  the  capability  of  reading  emotions  ,
though,  such  information  could  certainly   be   useful   in   diplomatic
negotiations and in rebel planning. A droid would be able  to  tell  whether
someone was being truthful or planning a trap.  In  such  a  case,  the  big
winner would be Vader. With a mask covering his face, his voice enhanced and
altered, and  his  respiration  and  other  bodily  processes  regulated  by
machinery, it would be very  difficult  to  read  his  emotions.  Using  the
techniques discussed, computers may in the near future have the  ability  to
recognize human emotions. But do Three- pio and Artoo have this ability?

     For Artoo, this question is difficult to answer. He actually  seems  to
rely, at least in part, on Threepio to interpret human emotions for him. The
most revealing evidence comes early in A  New  Hope.  Artoo  plays  part  of
Princess Leia's holographic message in front of Luke. He  tricks  Luke  into
removing his restraining bolt, then denies all knowledge of the message  and
fakes technical difficulties. Luke, angry and frustrated, is called away  to
dinner. Threepio tells Artoo he better play the message for Luke, and  Artoo
beeps back a question.

     Threepio answers, "No, I don't think he  likes  you  at  all."  Artoo's
question apparently is, "Does our new owner like me?" He seems  to  have  an
understanding of emotions and a sense of their importance,  yet  he  may  be
unable to evaluate human emotions himself, or  at  least  he  may  recognize
Threepio's  superior  abilities  in  this  area.  Threepio  here  reveals  a
sophisticated ability to detect emotions . Through Luke's angry tone,  sharp
emphatic gestures, and perhaps other signals, Threepio has deduced that Luke
is not pleased  with  Artoo's  behavior.  Thus  Threepio  has  an  important
function,  not  only  translating  words  between  humans  and  droids,  but
conveying emotions. Artoo can then  discover  how  well  he's  succeeded  at
pleasing his master. Threepio is also watchful for signs that he is pleasing
his master . When Threepio discovers Luke is giving him as a gift  to  Jabba
the Hutt, he puzzles over Luke's motivation, saying  Luke  "never  expressed
any unhappiness with my work."

     Obviously Threepio has been monitoring  Luke's  level  of  satisfaction
with him. Another example of Threepio's ability to  detect  emotions  occurs
when Luke is missing on Hoth. Threepio,  translating  Artoo's  beeps,  tells
Leia the chances of survival. After a moment of hesitation ,  Threepio  adds
that "Artoo has been known to make mistakes . . . from time to time." He has
realized, albeit belatedly, that Leia is upset and telling her the long odds
has only increased her concern. Not only does he  detect  her  emotions,  he
tries to change them and make her feel better. Threepio's abilities, though,
are far from perfect. In A New Hope, when  he  hears  Luke  and  the  others
crying out in  joy  that  the  trash  masher  has  stopped,  he  incorrectly
interprets their cries as screams of pain. Part of the reason for his  error
may be that he has only the poorly transmitted sound  from  the  comlink  to
judge by. Dr. Picard comments, "What's fascinating with that example is that
Threepio is making the same mistake that our state-of-the-art speech  affect
analysis makes."

     While computers can deduce the level  of  excitement  or  intensity  in
someone's voice, that can't  yet  reliably  tell  whether  that  emotion  is
positive or negative. Threepio  here  mistakes  a  positive  emotion  for  a
negative one. Without visual or other input, the  mistake  is  one  a  human
might well make. Threepio's biggest failure to read emotions occurs with Han
Solo. If Threepio understood how his complaints and protests irritated  Han,
he could attempt other methods of interacting with Han. But Threepio has Han
close to bursting a blood vessel through most of The Empire Strikes Back. He
irritates Han to the point that Han has Leia turn Threepio off! Certainly  a
robot who can  detect  emotions  should  know  enough  to  avoid  this  dire
situation . Yet let's look at things from Threepio's  point  of  view.  He's
apparently used to dealing with Princess Leia and other diplomats.

     And he seems to function fairly well  with  Leia  and  with  Luke,  who
treats him with respect. He may never have met anyone like Han Solo  before,
and so have trouble deducing Han's emotional state.  Han  expresses  himself
much differently than Leia. He's the king of sarcasm,  and  often  says  one
thing when he means exactly the opposite. Dr. Picard recognizes  this  could
be a problem. "Humor and sarcasm involve more than just recognizing  a  face
or a voice. They also require  some  situational  understanding  and  common
sense." A failure to recognize Han's tone  could  easily  lead  a  droid  to
misunderstand the meaning of what was said.  Sometimes  Threepio  recognizes
Han's sarcasm, as when he points out to Han that the asteroid they've landed
in is unstable. Han replies, "I'm glad you're here to tell us these things."
While the words themselves praise, Threepio clearly realizes that he's being
criticized and takes offense. Yet later, when Threepio  interrupts  Han  and
Leia's kiss to announce the exciting progress he's  made  in  repairing  the
hyper-drive, Threepio mistakes Han's sarcastic "Thank you.  Thank  you  very
much," for sincere praise.

     His ability to read sarcasm-or at least Han's sarcasm-isn't perfect. In
Threepio's eyes, then, Han  is  erratic:  sometimes  rude,  arrogant  ,  and
insulting; sometimes helpful and appreciative. If Three- pio  is  attempting
to please, these mixed signals could generate  conflicting  impulses  within
him. No wonder Threepio calls Han "impossible." Yet misunderstandings aren't
the only roadblock to a friendship between Han and Threepio. Han clearly has
a general dislike  of  droids.  If  Threepio  is  programmed  to  serve  his
owner-and his owner's friends-in a satisfactory and pleasing way, he's going
to have a long wait for his actions to bring a smile to Han's face.

     Even if Han didn't dislike droids, Threepio might  still  have  a  hard
time making Han happy. Not only does he need to detect  Han's  emotions;  he
needs to know how to respond suitably. "Knowing how best  to  respond,"  Dr.
Picard says, "may be a much harder skill for us to give robots." One  reason
humans have some ability to respond suitably to the emotions  of  others  is
that we have emotions of our own. This allows us to understand the  feelings
of others, or sympathize. Dr. Picard at first believed robots shouldn't have
their own emotions. "I wasn't sure they had to have  emotions  until  I  was
writing up a paper on how they would respond intelligently to  our  emotions
without having their own. In the course of writing that paper, I realized it
would be a heck of a lot easier if we just gave them emotions."

     For that to be  the  case,  the  robot  must  actually  have  emotional
reactions to what's going on around it. As we discussed earlier, both  Artoo
and Threepio have clear emotional responses  to  events  and  people.  Artoo
feels strong loyalty and friendship for both  Luke  and  Threepio.  Threepio
constantly describes himself in emotional terms, saying he's  "embarrassed,"
"sorry," and "afraid," and he even anticipates the emotional consequences of
an event: "I'm going to regret this."

     Even the tiny box-on-wheels droid on the Death Star appears freaked out
when it runs into Chewbacca, letting out a shriek and turning tail. But  can
we create a robot that feels pride, fear, frustration, and affection?



     I'M OKAY, YOU'RE AN "OVERWEIGHT GLOB OF GREASE"


     In humans,  emotions  arise  in  several  ways.  They  can  arise  from
chemicals in our bodies, from the way we carry our bodies- smiling can  make
you feel happier-from sensations, such as hunger or pain, or from  thoughts.
Just as a person seldom makes an entirely logical decision, a person  seldom
has a completely emotional reaction. There are a few exceptions, instinctive
emotional reactions that in essence hijack our bodies and occur without  any
thought at all. For example, if you see a large object flying at you, you'll
immediately feel a fear response and jump out of the way before you  have  a
chance to think. Such a response could be very useful in a droid, so that it
wouldn't get hit by stray speeders or blaster fire.

     In fact, Threepio displays  such  a  response  when  he  and  Luke  are
attacked on Tatooine by Sand  People.  As  a  Sand  Person  leaps  at  Luke,
Threepio's eyes light up and he jerks backward, falling over. This seems  to
be an instinctive rather than logical response. If Threepio had  stopped  to
think, he would have realized that he was standing at the edge of  a  cliff,
and that falling could cause him more damage than the Sand Person. In  fact,
the fall rips his arm out of its socket (much as an angry Wookiee might do).
Most emotions arise more slowly, in combination with thoughts. For  example,
a person on an unfamiliar desert planet could grow more and  more  concerned
as he walks farther and farther and finds no food, water, or shelter.

     As he realizes his resources are dwindling and he  may  die  before  he
reaches help, he will begin to feel fear. A droid  in  the  same  situation,
like Artoo on Tatooine in A New  Hope,  may  similarly  recognize  that  his
energy levels are falling and that he may not reach help before  his  energy
supply is exhausted. In such a situation, the droid may also feel "fear."

     Why would you want a droid to feel fear? Dr. Picard  explains  that  in
this state, the droid's priorities and behaviors could  change,  just  as  a
fearful  person's  priorities  and  behaviors  change.  A  person  will  use
adrenaline to push himself to his limits. He'll  become  more  watchful  for
threats and useful resources, and he'll focus all his attention  and  energy
on survival. A droid in the fear state  could  access  its  emergency  power
supply; channel additional power to its sensors to watch for signs  of  life
or dangers; shut down nonessential systems; and focus on survival  over  any
secret mission or other task. Artoo displays  additional  watchfulness  just
before he's captured by the Jawas. We might even imagine that he rolls  into
the Jawas' trap on purpose, his need for an energy recharge  overruling  his
instructions to complete his mission quickly  and  secretly.  In  such  dire
circumstances, the positive value of an energy recharge  far  outweighs  the
negative value of capture. Emotions in robots  can  thus  alter  priorities,
change behaviors, make judgments of value, and help make decisions flexibly,
quickly, and well.

     Similarly,  Threepio  exhibits  a  change  in  priorities  during   the
holographic chess game between Artoo and  Chewbacca  aboard  the  Millennium
Falcon. At first Threepio seems to want Artoo  to  win.  But  when  Threepio
learns that Chewbacca may become violent if he loses  the  game,  Threepio's
priorities change. His top priority is now to  avoid  angering  the  Wookiee
further: "Let the Wookiee win."

     If Artoo continued to play  at  the  same  level  of  ability,  he  and
Threepio might have ended up in a very  unpleasant  situation.  Fortunately,
the danger triggered a change in them equivalent to a change from  a  normal
state to a fear state. Yet if we enter the holographic chess scene  earlier,
we see that Threepio's change does not occur immediately. During  the  chess
game, Chewbacca howls when Artoo takes one of his pieces.

     Threepio complains, "He made a fair move. Screaming about it can't help
you." Threepio recognizes  that  Chewbacca  is  expressing  frustration  and
dissatisfaction. He may be deducing this from Chewbacca's body language, his
words, or his tone of voice. Yet at  the  same  time  he  is  dismissive  of
Chewie's feelings. His dialogue suggests Chewie should behave logically, not
emotionally. Threepio resists switching into a  fear  state,  preferring  to
maintain his original priorities and goals rather than  to  forego  them  in
reaction to Chewbacca's feelings. Just like a person,  Threepio  values  his
own feelings over anyone else's.

     A selfish robot? Yes, and this quality is necessary if Threepio  is  to
carry out preassigned tasks. If Threepio  valued  everyone  else's  feelings
above his own, he'd spend all his time trying to make  everyone  happy,  the
ultimate codependent enabler, rather than focusing  on  his  own  goals  and
duties. As it is, Threepio tries to make his owner and his  owner's  friends
happy, while at the same time operating  in  the  way  he  sees  proper  and
accomplishing his tasks.

     Although he is able to recognize others' emotions, his  recognition  of
them often doesn't change his own actions, rather like an insensitive human.
The other party's emotions must pass a certain  threshold  for  Threepio  to
change his goals. Dr. Picard agrees. "You don't want a computer changing its
behavior every time you twitch." She also  points  out  that  Threepio  only
changes his behavior when their mission is jeopardized. "Artoo  is  critical
to their mission. If the Wookiee damages Artoo,  that's  going  to  threaten
getting the information in Artoo to the people they need to get it to."

     When Han explains that it is  unwise  to  upset  a  Wookiee,  Three-pio
replies, "But sir, no one  worries  about  upsetting  a  droid."  This  line
provides a key to understanding Threepio. He obviously feels organic  beings
are insensitive to the feelings of droids, and that they have upset him many
times. Yet, in a very human way, he can be staggeringly insensitive  to  and
dismissive of the feelings of organic beings. It's only when his  safety  is
threatened-when he fears Chewie will rip them apart-that he decides to  take
Chewie's emotions into account.

     Threepio's top priority is, after all, saving his own neck. So a  droid
must not switch emotional states too easily, yet it  must  switch  when  the
situation warrants it. Since Star Wars  droids  are  so  emotional,  for  an
example of a failure to switch states, we actually have to turn to  a  human
character. If humans repress  and  ignore  their  emotions,  they  can  make
mistakes similar to those a computer without emotions might make. When Grand
Moff Tarkin is told the battle plan of the rebels poses a real threat to the
Death Star, he does not switch to a "fear state," which would be appropriate
in this situation. Instead he maintains his  previous  priorities-destroying
the rebels, proving the superiority of the Empire-which are inappropriate in
the face of this new information . The failure leads to his death. (Threepio
would have surrendered in a flash.)

     So emotions can be very useful for a  robot.  The  particular  emotions
that might be most helpful for a particular robot  depend  on  that  robot's
function. Dr. Picard believes that within the next year, we'll have computer
scientists calling themselves "personality engineers  "  who  will  consider
such  issues.  Actually,  Steve  Grand,  in  creating  the   computer   game
"Creatures," functioned as a  personality  engineer,  giving  his  creations
desires and emotions, like hunger , loneliness, and anger. His goal was  "to
create small furry creatures (Ewoks were in my mind  when  I  started)  that
people would enjoy  keeping  as  pets."  These  desires  and  emotions  help
motivate the creatures to learn and engage in lifelike behavior, which keeps
their human owners attached and involved in their lives.

     For a protocol droid, a love of all things  proper  and  a  dislike  of
inappropriate conduct might be helpful. Threepio certainly displays this. He
seems to hold Chewie in contempt for whining about the chess  game,  and  he
despises Jawas for  their  filthiness.  If  a  droid  is  meant  to  perform
complicated missions by itself, some useful emotions would be loyalty, fear,
and determination: emotions we see in Artoo and  Threepio.  If  a  droid  is
meant interact with people, an emotion like "affection" would be useful.  If
you feel affection for someone, you want to do things that make that  person
feel happy. A robot, then, would want to  do  things  that  make  its  owner
happy, that make its owner "like" it. Earlier, we noted that both Artoo  and
Threepio are concerned with pleasing Luke. Any behavior that displeased Luke
would carry negative associations that would deter the droids from repeating
it, while any behavior that pleased Luke would carry  positive  associations
that would encourage the droids to repeat it.

     When Threepio has Artoo shut down all the Death Star's garbage  mashers
before his owner, Luke, is squashed, Threepio feels good. The behaviors that
led to this outcome-remembering to turn on the comlink, working  with  Artoo
to solve the problem, taking a global action  rather  than  a  specific  one
(shutting down all the  garbage  mashers  rather  than  just  those  on  the
detention level), saving his owner  from  danger-would  all  be  reinforced,
connected with feeling good. So Threepio would be  more  likely  to  perform
such actions in the future. In addition to caring whether  Luke  likes  him,
Artoo is even concerned with whether Threepio likes him. After  Artoo  fails
to play Princess Leia's message for Luke, and Threepio tells Artoo that Luke
doesn't like him, Artoo beeps another question.  Threepio  answers,  "No,  I
don't like you either."

     Since Artoo and Threepio are "counterparts," it  would  make  sense  to
program them with "affection" for each other. If one droid is giving  output
that the other doesn't find useful, or  doesn't  "like,"  their  partnership
will not be very effective. In fact, this happens on  occasion,  as  in  the
situation just described, which leads to Artoo and Three- pio's affectionate
bickering. They seem to be in a constant negotiation , each trying  to  make
their relationship more pleasing or helpful  for  himself.  Artoo  tries  to
convince Threepio to follow Ar- too's priorities, and vice versa. Dr. Picard
points out that Artoo seems to carry more authority than Threepio.

     Threepio will follow Artoo when he has no idea what Artoo is doing,  as
when he joins Artoo in an escape pod at the beginning  of  A  New  Hope  and
drops to the surface of Tatooine. Yet Artoo will not follow Threepio  unless
he agrees Threepio's course of action is the correct one.  Perhaps  this  is
because Threepio is "younger" than  Artoo.  Since  Threepio  and  Artoo  are
programmed to work together, to try to help  and  please  each  other,  then
Threepio's sticking his neck out for Artoo is quite natural, and not at  all
beyond his capacity . While they are  occasionally  unable  to  cooperate-as
when they split up on Tatooine-they are usually able  to  work  together  to
satisfy both their goals.  This  creates  a  bond  of  trust,  loyalty,  and
friendship between them. Steve Grand is now embarking on a  project  with  a
colleague to build "something as close as we can get to a robot like Artoo."

     Yet he has decided that rather than  trying  to  build  one  robot,  he
should build twins. "Human twins tend  to  bond  strongly,  understand  each
other well and develop shared language and a shared understanding.  The  way
Artoo and Threepio interact is just like a pair of twins. I'll bear them  in
mind for inspiration !" Not all droids feel affection for each  other.  When
Artoo reports that the Cloud City computer told him the  hyperdrive  on  the
Millennium Falcon has been deactivated, Threepio berates Artoo for  trusting
a strange computer. Just as Artoo and Threepio would be programmed to try to
work  with  each  other,  they  would  be  programmed  with   distrust   and
secretiveness toward others,  for  security  purposes.  If  two  droids  are
programmed with compatible goals, one should be able to make the other  like
it. But what happens when a droid is unable to make its master like  it?  In
The Empire Strikes Back, Threepio warns Han of  the  horrible  odds  against
successfully navigating an asteroid  field,  attempting  to  save  him  from
danger .

     He is most likely repeating a behavior that has been  rewarded  in  the
past, and one that is deeply ingrained in his programming. Yet Han does  not
respond with happiness, as Threepio expects. This would make Threepio  "feel
bad." He would connect this behavior  to  negative  results,  and  would  be
motivated to come up with alternate behaviors to use in  future  situations.
Yet with Han, nothing Threepio does allows him to  "feel  good"-except  when
Threepio misunderstands Han's sarcasm for  sincerity.  And  his  programming
most likely forces him to  inform  humans  when  they  engage  in  dangerous
activities. Threepio's frustration and distress would grow, since  he  can't
avoid feeling bad. When a person feels bad,  the  way  he  perceives  things
changes. He feels it more likely that bad things will happen. This helps  to
explain Threepio's negative outlook, his belief that life  is  one  horrible
trial after the next, which seems particularly strong in this movie.

     To add to his stress, Threepio's life and the  lives  of  his  "owners"
have been in danger since the Empire's forces arrived at Hoth. He is scolded
for pointing out the dangers and is unable to do anything to stop the danger
himself. His behavior grows ever more frantic and desperate until he finally
suggests  surrender,  and  Leia  turns  him  off.  Dr.  Picard  offers   two
suggestions. First, Threepio "should find a good time to interrupt and  say,
'Han, I need some feedback from you. Every time I  present  you  with  these
statistical odds, you get really irritated at me.

     Should I simply stop doing that?' " Of course, this  solution  requires
Han let Threepio speak three consecutive sentences before shutting  him  up.
And that Han will not respond sarcastically, "No, Threepio, I love  it  when
you tell me the odds." Dr. Picard's second suggestion-have Han sell Threepio
or "take him back and have his  personality  reengineered.  Reengineering  a
human personality, though, takes a lot of work, years of therapy ,  and  you
don't know what you'll end up with. It may be that  way  with  robots  too."
Just as feeling bad affects a person's outlook,  so  does  feeling  good.  A
person who feels good tends to see the world "through rose-colored glasses,"
interpreting everything in a positive light. We see a brief glimpse of  this
when Threepio excitedly reports to the kissing Han  and  Leia  the  progress
he's made in repairing the hyperdrive of the Millennium Falcon. Threepio, in
his rush of positive feelings, mistakes Han's sarcastic thanks  for  sincere
praise. We talked at the beginning of this section about  the  chemical  and
thought processes  that  create  emotions.  We've  shown  how  thoughts  can
potentially lead to emotions in computers.

     But do computers need the equivalent of a chemical system to truly feel
emotions? Chemicals do play an important role in human emotions .  In  fact,
people  with  chemical  imbalances  will  feel  emotions,  such  as  chronic
depression, unrelated to events in their lives. If we are to re-create human
emotions in robots, then, don't we need a chemical equivalent? This  remains
a point of dispute among scientists . Dr.  Picard  believes  robots  can  be
emotional without any biochemical equivalent, and adding such an  equivalent
will not give robots the same feelings humans have.

     A robot's emotions will always be different than a human's, "because it
does not have the same biochemical and sensory apparatus that  we  have.  As
long as we have different bodies, we will have different 'feelings.' " Other
scientists believe emotions depend on neural-chemical reactions and  require
chemical agents. Dr. Rodney Brooks, director of the Artificial  Intelligence
Laboratory at MIT, has built a robot called Cog, which has  certain  desires
programmed into it.

     To create these desires, Dr. Brooks has programmed in internal rewards.
"We have computational simulations of endorphins and  hormonal  levels,"  he
explains. Certain activities bring Cog a virtual chemical reward, and so  it
desires doing those activities since they will bring further rewards.  Steve
Grand wanted to populate the computer game "Creatures " with creations  that
would seem to players to be alive. In fact, Grand  nervously  admits,  "It's
not really true that I designed  them  to  give  the  illusion  of  life;  I
actually tried to make them alive."

     To achieve this end, Grand combined a neural  network  with  a  virtual
equivalent of biochemistry. "I  created  computer  simulations  of  neurons,
biochemicals, chemoreceptors." Signals designed to mimic biochemical signals
in the body are released under different conditions,  strengthening  certain
desires and patterns of behavior while weakening others. Earlier  we  talked
about how neural networks can be trained by adjusting the strength of  their
various connections.

     Here, the virtual chemicals do the  training  ,  strengthening  certain
pathways and weakening others. So if the creature does something foolish and
injures itself, the "pain" it. feels will trigger it to weaken  the  pathway
of connections that led to that action. Whether through  thoughts  alone  or
through a combination of thoughts and virtual  chemicals,  future  computers
and robots  may  feel  emotions  much  like  you  and  I  do.  Emotions  can
potentially  make  computers  much  more  sophisticated  and  helpful.   The
decision -making abilities, flexibility,  and  independence  we  observe  in
Artoo and Threepio are all contingent on their ability to feel.

     In addition to helping computers function more  capably,  emotions  may
have other consequences as well. You  may  have  to  stop  cursing  at  your
computer. You don't want to hurt its feelings.



     I WHINE, THEREFORE I AM


     A robot may be a seething cauldron of emotions, but if it has no method
of conveying those emotions, we may never know it. If emotions make a  robot
a more efficient decision maker, a more flexible thinker, and a more helpful
assistant, why should we care if the robot can convey its emotions to us  or
not? This ability can be useful in several ways. First, we humans  are  used
to communicating with emotional beings, and we  actually  prefer  it.  In  a
study by Dr. Tomoko Koda at MIT, people played  two  different  versions  of
electronic poker,  one  with  an  animated  face  that  displayed  different
expressions as the game progressed, and another one with no face.

     When surveyed after their games, a majority of people preferred playing
with the animated face. They were simply more engaged in the game and  found
the face likable. In another study, it was even found that people  preferred
interacting with an animated character of their own ethnicity. If we are  to
interact regularly with a robot, it may be helpful to have the robot  appear
humanoid, and to appear to convey emotions . In my Microsoft  Word  program,
the help icon is a small, animated  paper  clip,  Clippit.  Clippit  blinks,
sways, and looks back and forth as I write this book.

     When I open a file, she raises her eyebrows in surprise. When I command
the program to search for a word in my text, she contorts  into  a  fiercely
concentrated expression . While Clippit doesn't actually  feel  emotions  in
the sense that we discussed, she does simulate emotions, and that simulation
makes me feel a bit more charitable toward her when her "help" fails  to  be
helpful. Even more than making us patient with software, the ability to show
emotions can be used to manipulate our emotions.

     My research assistant, Keith Maxwell, came in one day  with  his  fianc
ee's digital pet, or Tamagotchi, as they  were  originally  called.  He  was
under strict orders to feed, care for, and play with the  tiny  computerized
turtle image. When she first gave it to him, he says, "I thought it was kind
of stupid, because I thought who cares about a little beeping toy. You don't
get any return from it." As he cared for it, though,  he  was  surprised  to
find  that  playing  with  the  "silly  thing"  was  actually  pleasing  and
rewarding: "Every day it would have a birthday, and it would  get  a  little
bigger, and its weight would go up a little. So it was interesting to  watch
it grow." The image has been designed to make us feel affection for  it,  to
actually manipulate our emotions. The technology is limited, though, and  so
is its success. As Keith says, "I guess I cared about it for a day  or  two.
Then I grew to hate it. It was always so irritating , always beeping."

     Rather like Han's reaction to Threepio, I'd say.  Luckily  his  fiancee
took back the pet before any violence ensued . Since digital pets might  not
be lovable enough, more cuddly electronic pets have  been  developed.  Plush
and huggable, Furbys are five-inch-tall cuddly  balls  of  fur  that  laugh,
dance, and make different facial expressions. Their vocabulary of more  than
two hundred words allows them to interact with  owners,  and  even  to  tell
them, "I love you."

     With their big eyes and floppy ears, they've been designed specifically
to be lovable. Yet apparently some of  these  carefully  designed  high-tech
toys rub owners the wrong way. On the  Internet  you  can  find  Furby  guts
graphically exposed on the Furby Autopsy  Home  Page.  So  a  computer  that
displays emotions may gain our loyalty and affection, yet it may also arouse
our anger.



     ARE YOU AND YOUR COMPUTER MAKING A LOVE CONNECTION?


     Steve Grand reports that the nearly one million  players  of  his  game
"Creatures " experience a wide range of emotional reactions,  many  of  them
responding to the creatures as if they are truly alive. "People often grieve
when their creatures die."

     Once, when he was showing his mother an early version of the  game,  We
watched as a couple of creatures  engaged  in  a  chase  scene  that  looked
remarkably like 'unrequited love,' and then the  program  crashed.  My  poor
mother shed a tear when  I  explained  that  her  creatures  were  now  gone
forever!" Even Grand himself has fallen under the creatures' spell.  "I  was
once sent a sick creature by E-mail from Australia, with a plea to  cure  it
of a disease that was causing it to just stand there and waste away.  I  did
some experiments and discovered that it had been born deaf and blind, and so
had no idea there was a world  of  food  out  there.  I  figured  out  which
simulated gene had mutated and caused the defect,  and  after  much  genetic
manipulation and tender loving care, I managed to put it right.

     Then I mailed her back to  her  owners.  It  was  only  later  that  it
occurred to me that I was just as soppy as they were, having spent  a  whole
day worrying about the health of a data file!"

     In a similar way to the Tamagotchi or Clippit, Artoo, without words, is
able to convey emotions as well. His robot language of  whistles  and  beeps
appears to have been created so that humans could read some basic  emotional
content in it. Our feeling that we "understand" Artoo contributes greatly to
our affection for him. While Threepio's face is not  expressive,  his  voice
and his body are. His tone is quite revealing of emotion, and  his  gestures
and body language also convey cues about his emotional state. Since Threepio
is fluent in six million forms of communication, we might assume he not only
knows  six  million  languages,  but  six  million  patterns  of   emotional
expression-intonations, expressions, and body language.

     He uses his ability to convey emotion to  add  emphasis  to  points  he
feels are important, and even to try to influence the emotions of others. In
The Return of the Jedi, Threepio tells the story of the Star Wars adventures
to the Ewoks in order to gain their help for an attack on the Imperial base.
Any good storyteller must manipulate the emotions of his audience, and  that
is exactly what Threepio does. He skillfully selects details that will  call
up the desired emotions in the  Ewoks:  fear  and  hatred  for  the  Empire,
affection and loyalty for the rebels.

     And he presents  these  details  with  intonations  and  gestures  that
reinforce these emotions. Critical to the success  of  robots  that  display
emotions is the ability we discussed earlier to detect emotions. If you  are
furious that your robotic maid has just thrown out your Star Wars videotapes
, a smile on the maid's face is not going to make you feel kindly toward it.

     You  would  want  the  maid  to  acknowledge  your  anger  and  display
penitence. Perhaps that's why Furbys are ending up on the autopsy table. Dr.
Fumio Hara is developing a system to  address  this  issue  at  the  Science
University of Tokyo. He has built a robot that  can  display  six  different
emotions: joy, sorrow , hatred, horror, anger, and surprise. He  is  now  at
work on a program that will be able to recognize various facial  expressions
on humans. He plans to connect that program to the  robot  so  that  it  can
register  the  expression  of  a  human  and  then  display  an  appropriate
expression in response. If we can someday make robots  more  perceptive  and
understanding of our emotions, and more responsive to them through their own
emotions and  expressions,  we  may  actually  finally  build  the  ultimate
artificial intelligence: one that does not drive us insane .



     THE SIX-MILLION-DOLLAR SITH


     In addition to droids, Star Wars also features a few cyborgs, organisms
with mechanical or electronic components. After Luke's hand is  cut  off  by
Darth Vader, he receives a bionic hand in its place. The hand looks  like  a
real hand, and seems to have all the mobility and strength of a real one. In
Return of the Jedi, Luke returns the favor, cutting off Vader's hand, and we
see wires coming from Vader's wrist. Vader's hand  is  artificial  as  well.
When the Emperor strikes Vader with bolts  of  Force  energy,  we  see  that
Vader's entire arm is artificial.

     Perhaps his legs are as well; we can't tell. Are such artificial  limbs
possible? While our technology is a long way from the bionic limbs shown  in
Star Wars, prosthetic limbs that look and feel  pretty  close  to  the  real
thing are now available. Artificial hands can even perform simple actions. A
myoeletric sensor is implanted into the user's residual limb, or  stump.  By
flexing the muscles in the stump, the user can trigger the  sensor  to  send
signals along a wire to a motor in the limb. With  training,  the  user  can
flex particular muscles to send specific commands to the limb, making a hand
open, close, or turn.

     Prosthetic limbs can even be outfitted  with  temperature  or  pressure
sensors, so that the temperature of a hot cup of coffee in a user's hand  or
the pressure of the hand against the cup can be detected. The information is
transmitted from a sensor in the fingertip along wires to the residual limb.
In the case of temperature, the signal heats or cools a metal plate  on  the
stump to reflect the temperature of the object being held. This  allows  the
user to regain some long-lost sensation and can help him avoid damaging  his
new hand. In the  case  of  pressure,  a  tingling  sensation  reflects  the
intensity of the hand's pressure against an object.

     Before, users had  to  judge  by  sight  whether  they  were  clutching
something tightly enough, which made for  many  accidents.  One  new  design
actually senses when  an  object  is  starting  to  slip  and  automatically
tightens its grip. People with these prosthetic hands can use them  to  eat,
brush their teeth, and answer the phone. Sensors would allow  Luke  to  grip
his light saber firmly, and to  feel  the  warmth  of  Leia's  hand.  Luke's
fingers, though, are capable of independent movement, unlike the  artificial
hands currently available.

     But an even  more  sophisticated  hand  is  now  under  development  by
scientists at Rutgers University. In this model, finer movements of  muscles
and tendons in the arms are used to  send  signals  through  a  computer  to
motors that move individual fingers. One patient testing the  hand  actually
played the piano with it. In addition to the hand,  other  prosthetic  limbs
are becoming much more comfortable  and  sophisticated.  In  older  devices,
residual limbs used to be held within liners and sockets  that  were  either
too tight, cutting off circulation, or too loose, generating friction. Users
would develop blisters and infections, and suffer serious pain.

     Now, more comfortable liners and sockets allow artificial limbs  to  be
worn longer, without hurting the user. Rather than  being  made  from  heavy
plastics, wood,  or  rubber,  prosthetic  legs  are  now  made  from  carbon
composite, the superstrong , light material  from  which  fighter  jets  are
made. One type, the Flex-Foot, uses shock-absorbing springs at the  toe  and
heel to bounce from one step to the next and  provide  stability  on  uneven
surfaces. Knee joints that used to operate with a mechanical hinge  are  now
hydraulic. The flow of fluid inside the joint adjusts the swing of the lower
leg to the user's stride, so it swings  faster  when  the  user  is  walking
quickly or running.

     A computer chip is even being added to the knee, which will measure the
user's pace and adjust the swing with a tiny motor up  to  fifty  times  per
second. With such legs, users have run races, played  basketball,  and  even
climbed mountains. Sensors  also  play  an  important  role  in  the  latest
artificial legs. Three sensors near the heel and three near the  toes  relay
information about pressure on different parts of the foot to  electrodes  in
the user's residual limb. To the user, these tingles quickly begin  to  feel
like sensations coming directly from the foot.

     Able to feel the pressure of the ground against their  feet,  they  can
maintain their balance much better. Scientists have even figured out how  to
make artificial limbs that can change skin tone to keep  up  with  a  user's
tan. Most limbs have a latex covering that is matched to the user's body.

     But if the user tans or becomes pale, the tone will  no  longer  match.
Dr. Henry LaFuente at the University of Oklahoma Health Sciences Center  has
designed a limb covering made of two transparent layers , one  silicone  and
one nylon. The layers have a tiny space between them. Dye of any  color  can
be injected into that space to change the "skin tone" of the limb.

     This could come in handy if  Vader  decides  to  equip  his  meditation
chamber with tanning lights. Beyond his limbs, we don't really know how much
more of Vader may be artificial. Obi-Wan says of  his  former  pupil,  "He's
more machine now than man." We do know that he breathes with the  assistance
of a ventilator, and his voice is artificially augmented somehow.  The  Star
Wars Encyclopedia tells us that Anakin fell into a molten pit during a  duel
with Obi-Wan.

     Let's examine what sort of damage would be caused by these  burns,  and
whether they can account for Vader's condition. We don't know the nature  of
the molten pit, but we might imagine it contains  fresh,  hot  lava.  During
volcanic eruptions, many people have been burned to  death  by  lava  flows.
Lava ranges in temperature from 1,400 to 2,200  degrees,  which  means  that
cloth, wood, or paper would immediately ignite. And skin cells would  almost
instantaneously shrivel and die.

     Before we can figure out the exact damage to Anakin, though, we need to
know how much of his body comes into contact with the molten material, which
determines the extent of the burn, and how long  it  is  in  contact,  which
determines the depth of the burn. One major factor is  the  density  of  the
molten material. Lava is quite dense. If the pit  contains  molten  rock  or
molten metal, the liquid will be much denser than a  human  body,  which  is
comprised mainly of water.

     If Anakin gently lays back on the molten material, then, he will float,
only sinking an inch or two into the lava. This will limit burns to about 15
to 20 percent of his body. If he happens to step into this pit by  accident,
he will sink in about up to his knees. If he drops into the pit from a great
height, though- which seems a bit more likely-his momentum  will  carry  him
deeper into the lava before he bobs back up, like a bar of soap dropped into
a sink full of water.

     How far he goes into the lava depends on his velocity when he hits  the
surface. Since lava is so dense, though, we might guess that he  doesn't  go
much deeper than the surface. And the heavier density of the molten material
will drive his body up quickly, limiting the exposure of most of his skin to
a few moments. The density of the lava may well be what saves Anakin's life.
Since Anakin's face was not seriously burned, we can assume he  didn't  fall
on his face. Perhaps he landed on his feet. In that case, the  most  serious
damage would have been done to his legs, since they would have  remained  in
contact with the lava until he walked out of the pit, levitated himself out,
or was rescued.

     He might have struggled to balance himself with  his  hands,  immersing
his arms in the molten material as well. The case of a  foundry  worker  who
stepped into a pot of molten metal can  perhaps  shed  some  light  on  what
injuries this might  cause.  In  accordance  with  safety  regulations,  the
foundry worker was wearing fireproof trousers and leather boots  with  metal
tips, which served to partially protect him from the  molten  metal.  Anakin
most likely didn't have any protective gear on. Yet  the  molten  metal  the
foundry worker stepped in was 2,400 degrees, hotter than lava. The  worker's
boot was almost completely destroyed.

     Just a small shriveled-up bit was left, about the size of the sole. The
worker suffered third-degree burns on his right foot and leg up to the knee,
and second-degree burns on his hands and face,  from  spattered  metal.  You
might expect that his leg had to be amputated . Yet it didn't.  The  initial
scars, called eschars, had to be treated immediately. Dr. Michael  Blumlein,
physician and teacher, explains that since scar tissue is rigid, if  a  scar
goes all the way around  the  circumference  of  a  limb,  the  eschar  "can
constrict blood flow to the area, leading to the possibility  of  gangrene."
The limb can become paralyzed , numb, and cyanotic.

     If the  doctor  cuts  into  this  scar  tissue,  in  a  process  called
escharotomy, the constriction can be relieved and gangrene prevented. A  few
days later, the worker's dead skin was surgically excised with  a  specially
designed knife that can shave a thin layer of  dead  tissue  off  the  body.
Since the skin in some areas was  completely  destroyed,  skin  grafts  were
applied over several operations. The worker was left with minor scars on his
hands and face, and more serious scarring on his foot and leg,  but  he  was
able to walk fairly  well  with  just  a  cane.  And  this  case  isn't  the
exception.

     In  twenty  other  cases  of  splash  burns  from  molten  aluminum  at
temperatures ranging from  600  to  1,300  degrees  ,  no  amputations  were
required. We can also consider the cases of two  geologists  who  fell  into
lava at the Hawaiian Volcano Observatory. The lava  wasn't  very  deep,  and
they got out quickly. After  hospitalization  for  their  burns,  they  both
recovered  without  any  serious  permanent  injury.  Exposure   to   molten
materials, then, need not be lethal or even crippling, as long as the amount
of body exposed and time for which it is exposed  aren't  too  great.  While
Anakin may land on his feet in the pit, it seems most likely that  he  would
land on his back.

     At such high temperatures, the clothes on Anakin's  back  would  almost
instantaneously burn off, and the  skin  would  follow  quickly  after,  the
proteins in it literally cooked so that what remains is rigid and dead. In a
few seconds the external cartilage of the ears and the tissue of his fingers
and toes would begin to burn off. With each  moment,  heat  would  penetrate
deeper and deeper into the back of his head, neck, his back, and  the  backs
of his arms and legs, burning through fat, connective tissue, muscle, nerve,
and even bone. The rest of his body would be burned by  the  heat  radiating
from the lava, though less severely. As Anakin gasped in shock,  superheated
air, steam, and volcanic gases would burn his mouth and upper airway.

     If the gases were hot enough, even Vader's  lung  tissue  might  suffer
thermal damage. Oddly, after the initial shock, Anakin would feel  no  pain.
Third- and fourth-degree burns are  actually  painless-at  least  until  the
surgeries and treatments begin. The worse the burn, the less the pain.

     If significant amounts of Vader's muscle tissue had  to  be  removed  ,
like the dead tissue in the foundry worker, Anakin would be  left  extremely
weakened. Heavy scarring on the limbs could cause additional  problems.  Dr.
Blumlein explains that scarring "can be devastating, not  just  to  physical
appearance, but to functional ability. Scar  tissue  can  be  so  thick  and
tenacious that joints can become frozen. I've seen people who couldn't  move
their necks, or hands, or fingers, because of constriction from scars."

     Much of this can be avoided or lessened through  techniques  like  skin
grafts  and  reconstructive  surgery.  Yet  Vader  might   actually   prefer
amputation, if flexible, strong bionic limbs are available as  replacements.
Damage to the airway and lungs is one of the most frequent causes  of  death
in burn patients.

     Yet usually if a patient survives the acute phase of  the  injury,  his
breathing problems will clear up and leave no  long-term  damage.  If  Vader
suffered some damage and scarring of his lung tissue, though, he might never
regain normal functioning. This might require a system that can  enrich  the
oxygen content of regular air and pump  that  enriched  air  into  Vader  's
lungs. Another possibility is that Vader's  phrenic  nerves  may  have  been
damaged from his burns. The phrenic nerves stimulate  the  movement  of  the
diaphragm, a muscular membrane that causes the  lungs  to  fill  and  empty.
Since the phrenic nerves come out to pump air in and out of  his  lungs  and
move his burn- damaged limbs. But I guess even a lord of the Sith gets tired
sometime .

     We started out this chapter asking whether robots  of  the  future  are
likely to be similar to Star Wars droids. The truth is that recent  theories
and research make emotional robots like  Artoo  and  Three-  pio  much  more
likely than they seemed back when A New Hope first came out. While we  still
have a long way to go in designing bipedal robots and robots that can  truly
"see," "hear," understand , and feel, robots of the  future  may  very  well
resemble those built "a long time ago, in a galaxy far, far away."

     What other wonders might the far more  advanced  Star  Wars  technology
produce? In the next chapter, we're going to explore one of  their  greatest
accomplishments: the ability to  travel  quickly  across  vast  interstellar
distances.

     Spaceships and Weapons

     You never heard of the Millennium Falcon? It's the ship that  made  the
Kessel Run in less than twelve parsecs. -Han Solo, A New Hope

     We've whooshed down the Death Star trench in an X-wing. We've navigated
an asteroid field against impossible odds. We've maneuvered through dizzying
battles. We've felt the vertiginous rush of the jump  to  hyperspace.  We've
outshot TIE fighters, outrun star destroyers, and destroyed Death Stars. One
of the most striking and exhilarating elements in the Star Wars saga is  the
spaceships.

     That opening shot of A New Hope,  in  which  a  star  destroyer  glides
endlessly over our heads in pursuit of Princess  Leia's  ship,  reveals  the
awe-inspiring dimensions of that vessel. And the star destroyers are dwarfed
by the mother of all spaceships, the Death Star. These  ships  are  equipped
with high-powered lasers that can disable or destroy another ship, or in the
case of the Death Star, even destroy a planet. They can travel quickly  over
vast interstellar  distances,  keeping  their  passengers  in  comfort  with
artificial gravity. And all without stopping for a fill-up.

     Star Wars vessels aren't the most  glamorous  ships  we've  ever  seen;
covered with bumps and nubs, towers and guns, they  have  a  cluttered  look
that prompts Luke to comment about Han's precious Falcon, "What a  piece  of
junk!"

     They also at times break down. But  that  only  makes  them  feel  more
realistic. But how likely are these vessels? While life in  "a  galaxy  far,
far away" is fast paced and exciting, can we imagine ways in which we  might
someday be able to travel quickly and easily among the stars?



     186,000 MILES PER SECOND


     We all know the law. Spaceships cannot travel at the  speed  of  light.
Einstein's special theory of relativity  established  the  speed  limit  and
revealed that just approaching the speed of light causes horrible  problems.
Let's do a little thought experiment-and be prepared, you'll find several in
this chapter. Theoretical examples tend to be the best way to understand the
issues involved in space travel. Han Solo  blasts  the  Falcon  out  of  Mos
Eisley spaceport, and stormtroopers on  Tatooine  observe  him  accelerating
toward light speed. But as he approaches the speed of light, several strange
things happen. The stormtroopers focus their scanners on the ship.

     The Falcon is now traveling at three-quarters the speed of  light.  But
the ship's mass appears to be one and a half times what it was when the ship
was landed in the spaceport. That doesn't seem right, they think. Even if he
jammed the entire ship full of spices, it wouldn't weigh that much. And  the
length of the ship measures only two-thirds what the registration shows.

     The stormtroopers compare notes for a moment, then check  the  scanners
again. The Falcon .9 the speed of light. But now the mass is over twice what
it  should  be,  and  the  length  of  the  ship  is  less  than  half.  The
stormtroopers look over their shoulders, checking that Darth  Vader  is  not
nearby to witness their confusion, then check the scanners once  again.  Now
the Falcon is traveling at .999 the speed of light. It's almost reached  the
magic number. But now the ship's mass is over twenty times as  great  as  it
was, and its length is just one-twentieth what it was. It's  shrinking  into
nothing!

     The stormtroopers, afraid crushed necks may be in their futures ,  pull
out the super-duper scanner, for use only in emergencies . With  this,  they
can actually see into the Falcon itself. They  scan  through  the  interior,
noticing that the Falcon's clock is ticking very slowly. In fact, for  every
twenty seconds that pass on Tatooine , only one second passes on the Falcon.
As the stormtroopers scan into the cockpit, they see Han Solo  talking  very
slowly. One, who is adept at lipreading, watches Han  patiently,  eventually
making out two words: "dusting crops."

     This is truly  the  most  confusing  case  they've  ever  investigated.
Checking  to  see  that  they  haven't  been  observed,  they  lock  up  the
super-duper scanner and move  quickly  away.  What  the  stormtroopers  have
observed are simply the results of the special theory of relativity. As  Han
travels closer and closer to the speed of light, they observe  the  Falcon's
length becoming shorter and shorter. The clocks tick slower and slower.  And
the Falcon's mass becomes greater  and  greater,  requiring  more  and  more
energy to accelerate a bit closer to Han's  goal.  Slowly  he  gains  speed,
expending huge quantities of energy.

     As he approaches the speed of light,  he  becomes  infinitely  massive,
requiriio infinite energy to accelerate that last tiny bit. He'll never make
it' Because of this, only objects that have no  mass,  such  as  light,  can
travel at the speed of light. We can't. Einstein discovered this  limitation
when he realized that the speed of light will always be measured to  be  the
same, no matter what the observer's speed is relative  to  the  light.  This
goes against every instinct we have. Let's try another  thought  experiment.
Imagine you are standing on the forest moon of Endor. A  speeder  approaches
you at 50 miles per hour. On it you see Darth Vader and Leia.

     They are fighting. The handle of the speeder breaks off in Leia's hand,
and she throws it at Vader. She has a pretty good  arm  and  can  throw  the
handle at 20 mph. Since she throws the handle  in  the  same  direction  the
speeder is traveling, you measure the handle moving at 70  mph.  The  handle
bounces off Vader's helmet. He's startled, but not hurt.  Unhappy  with  the
results, Leia draws a blaster and fires the laser weapon at Vader. The light
from the laser leaves the blaster at the  speed  of  light,  c.  You  should
therefore measure the light traveling at c + 50 mph.

     Yet you don't. The light is traveling at only c. How is that possible?

     The only way for the velocity of light to remain constant is  for  your
measurements of distance and time to change. Since velocity is calculated by
dividing distance traveled by time, these quantities must change just enough
so that no matter how fast the speeder is traveling, you will always measure
Leia's  laser  fire  traveling  at  c.  In  this  case,  just  as  with  the
stormtroopers observing the Falcon, the length of the speeder, and similarly
the distance traveled by the laser beam, would  shrink  slightly  from  your
point of view. You would also observe events happening more  slowly  on  the
speeder, just as the Falcon. You would measure  more  time  passing  between
Leia's firing of the blaster and Vader's being hit, than Leia herself  would
measure.

     These quantities would change just  enough  so  that  when  you  divide
distance by time you will get exactly c. Before relativity, we thought  time
and distance were absolutes. After relativity, the only absolute left is the
speed of light. Einstein's  theory  of  special  relativity  has  frustrated
scientists and science fiction fans ever since 1905. If the speed  of  light
forms a barrier, and we can't travel at the speed  of  light,  then  we  can
never travel faster than the speed of light.  If  we  sent  a  spaceship  to
another star, it would not return for years at best.

     Galactic republics or empires like those  shown  in  the  movies  could
never form. "Star wars" could never occur-or at least  not  on  a  timescale
that would keep moviegoers interested. So is there no  hope  that  something
like Star Wars could ever happen, even "a long time ago in a galaxy far, far
away"?



     SEPARATED AT BIRTH


     Queen Amidala gives birth to bouncing baby twins, Luke and  Leia.  Obi-
Wan makes arrangements for the twins to be separated. Leia must be hidden on
Alderaan, while Luke will live on  Tatooine  under  Obi-Wan's  protection  .
Obi-Wan decides he will first take Leia to Alderaan, then return and pick up
Luke for the trip to Tatooine. Amidala holds the one-year-old twins together
for one last time, bids a sad farewell to Leia, and Obi-Wan leaves with  the
infant. The trip to Alderaan is not for, Obi-Wan  decides  he  can  make  it
without jumping to hyperspace. He travels at a constant speed of  .9999  the
speed of light. The journey takes one month, during  which  Obi-Wan  wonders
why he ever volunteered to change diapers. He entertains himself by braiding
Leia's hair into bizarre designs. When he arrives at Alderaan, he  discovers
the planet is crawling with Imperial forces.

     He's unable to land safely, and has to turn around  and  head  back  to
Amidala, spending another  month  at  .9999  the  speed  of  light  changing
diapers. He brings Leia from the ship to see her mother. But Amidala appears
changed, much older. Obi-Wan decides the separation  must  have  pained  her
horribly. Then a boy runs into the room and asks to see his sister. Obi- Wan
is shocked when Amidala tells him this is Luke. He  is  now  thirteen  years
old, though his twin Leia is only one year and two months old. This  is  the
famous "twin paradox" of relativity, and it accurately reflects  what  would
happen in such a situation.

     Relativity reveals that time is not some absolute cosmic clock  ticking
the same for everyone. The time that passes for each  person  is  different,
depending on where he goes and how he moves. That is because time and  space
are not two separate  qualities,  but  a  single  interconnected  space-time
continuum. While such effects are minimal in our everyday lives, they become
dramatic at speeds close to the speed of light. The  good  news  is  that  a
space traveler can get from one place to another  with  only  a  short  time
passing for him. In our example, Obi-Wan travels to  Alderaan  in  a  month.
Let's consider how for he traveled. Before he  leaves,  Obi-Wan  charts  his
course with Amidala. She notes that Alderaan  is  34  trillion  miles  away,
almost six light-years.

     If he travels very close to the speed of  light,  it  should  take  him
twelve years to make the round trip. But Obi-Won knows that once he  reaches
his cruising speed of .9999 c, he will measure the distance between  himself
and Alderaan as only 482 billion miles, or one-twelfth of a light-year.  The
distance will have contracted, just like the length of  the  Falcon  in  our
earlier example. Thus  Obi-Wan  can  make  the  trip  in  only  two  months.
According to the time and distance measured by Obi-Wan, he will be traveling
at .9999 c. And according to the time and distance measured by  Amidala,  he
effect would constantly arise.

     For example, in The Empire Strikes Back, Luke  promises  Yoda  he  will
return to Dagobah to complete his training. He flies off, has his  encounter
with Darth Vader at Cloud City, gets a new hand, saves Han  from  Jabba  the
Hutt, and then heads back to Dagobah. While Luke may do all this in  only  a
month, for Yoda decades may pass before Luke shows up again. It's enough  to
try even a Jedi's  patience!  Since  Luke  seems  to  have  spent  a  fairly
uneventful life on Tatooine up until the beginning of A New Hope,  and  Leia
seems to have done a fair amount of traveling in her work as a diplomat  and
a rebel, Leia would certainly be many years  younger  than  Luke  when  they
finally meet.

     Such time dilation would make it very difficult for Luke and his  rebel
friends to destroy the Empire in a timely manner. Han seems to transport the
Death Star plans from Tatooine to the moon of Yavin  in  about  a  day.  Yet
years may have passed for everyone else.  The  Empire  could  have  built  a
completely new weapon that makes the Death Star look like a squirt  gun.  Or
the Emperor may have died of old age!



     WHEN "FASTER THAN A SPEEDING BULLET" JUST AIN'T FAST ENOUGH


     So we really don't want to travel at near-light speed to get around. We
want to get where we're going before everyone we're going to visit is  dead.
That means traveling at truly faster-than-light speeds-faster for  both  the
person traveling and the person staying at home. But first things first. Why
worry about how to break the speed of  light  when  our  current  spacecraft
can't get anywhere near that speed? The method we use for space travel today
is propulsion, whose workings are explained  by  Newton's  Laws  of  Motion.
According to Newton's second and  third  laws,  the  total  momentum  of  an
isolated system must remain constant, and every action requires an equal and
opposite reaction. As the space shuttle sits on its launching pad, the total
momentum of it and its fuel  is  zero.  As  the  shuttle  is  launched,  the
downward momentum of the exhaust gases creates an equal upward  momentum  in
the shuttle. Thus the total momentum remains zero, and the  exhaust  propels
the shuttle upward.

     In this method, the spacecraft and the  fuel  are  essentially  pushing
against each other. This makes  propulsion  particularly  suited  to  space,
since in space, there isn't anything much to  push  against  but  ourselves.
Some Star  Wars  ships  appear  to  use  propulsion,  at  least  under  some
circumstances. When the Falcon comes out of the asteroid field in The Empire
Strikes Back, it comes under attack by several  star  destroyers.  The  rear
deflector shields fail, and Han decides to make a frontal assault on one  of
the star destroyers. As he turns the Falcon around and  thrusts  toward  the
enemy ship, a white light flares out the back, as if material is being  shot
out of the ship. The problem with propulsion, which is obvious if you take a
look at the space shuttle on the launching pad, is that you have to carry  a
lot of fuel, which makes your spacecraft very heavy. And a heavy  spacecraft
requires yet more fuel to accelerate it.

     Also, our current chemical  engines  are  not  the  most  efficient  at
creating high-momentum exhaust, which is what we need to accelerate our ship
to high velocities. Momentum is equal to the mass times  the  velocity,  and
the velocity of chemical engine exhaust is not  terribly  high.  In  a  good
chemical rocket, the velocity of the exhaust is about 10,000 miles per  hour
or 2.8 miles per second. That's  fifteen-millionths  or  .000015  times  the
speed of light. Accelerating our rocket to the speed of the exhaust  is  not
too difficult. To do that, we'll need a mass of fuel only 1.7 times the mass
of the ship. That gets our ship to .000015 c.

     Excited yet? Since our chemical rockets can't  create  exhaust  with  a
much higher velocity than this, if we want to increase the momentum  of  the
exhaust, we must increase its mass. To accelerate  the  ship  to  twice  the
speed of the exhaust, we need 6.4 times the mass of the  ship  in  fuel.  In
this way, we can increase the speed of our ship by shooting out greater  and
greater masses of exhaust. The problem is that soon the  increases  in  mass
become prohibitive. In fact, scientists have  shown  that  to  accelerate  a
space shuttle-sized ship to just .004 times the speed of light, the mass  of
fuel we'd need is greater than the mass of the entire universe!

     So we aren't able to get anywhere near the speed of light with  current
methods of propulsion. What methods might provide  better  results?  Nuclear
fusion is often raised as a possible source of energy for propulsion.  There
are hints that fusion plays a role in the Star Wars universe. When  breaking
Princess Leia out of the Death  Star's  detention  center,  Han  pretends  a
dangerous "reactor leak" has destroyed all the surveillance devices.  Inside
the second Death Star, Lando shoots at the "main reactor."

     The Star Wars Encyclopedia  even  says  that  "Hyperdrive  engines  are
powered by fusion generators." But could fusion  provide  that  much  power?
Going back to our momentum problem, the other way to increase  the  momentum
of the exhaust, besides increasing its mass, is to increase its velocity. As
we saw, the velocity of chemical rocket exhaust is pretty  low.  Fusion  can
potentially provide exhaust  with  a  higher  velocity.  In  the  controlled
nuclear fusion envisioned to provide power, hydrogen nuclei or their heavier
isotopes fuse to form a helium nucleus. The new nucleus has  a  bit  smaller
mass than the sum of the original nuclei. That tiny bit  of  mass  has  been
converted into a large amount of energy, according to Einstein's equation  E
= mc2. This famous equation reflects the idea that matter is just a form  of
energy. Some  scientists  say  matter  is  frozen  energy,  or  confined  or
condensed energy.

     So the fusion process frees a small amount of the  energy  confined  in
the hydrogen. That newly freed energy can propel the resulting helium nuclei
out the back of the space ship at very high  speeds,  perhaps  one-twentieth
the speed of light. Just one ounce of hydrogen  fuel  can  provide  as  much
energy as over seventy  thousand  gallons  of  gasoline!  Even  though  this
process is about twenty times more efficient than current  chemical  methods
of propulsion, less than 1 percent of the mass of the original  hydrogen  is
converted into energy. So it's still not terribly efficient.

     But the higher speed of the exhaust helps  a  lot.  Just  as  with  the
chemical rocket, to accelerate the ship to the speed of the exhaust we  need
1.7 times the mass of the ship in fuel. But while that amount of fuel brings
a chemical rocket to only .000015 c, this amount of fuel brings  the  fusion
rocket to one-twentieth the speed of light, or  .05  c.  And  just  as  with
chemical rockets, if we want to accelerate the ship to twice  the  speed  of
the exhaust-in this case one-tenth c-we need 6.4 times the mass of the  ship
in fuel.

     Again, though, as we try to accelerate the ship further, the quantities
of fuel required rapidly increase. And as we get  closer  to  the  speed  of
light, relativistic effects make the situation even worse.  As  our  initial
thought experiment showed, the stormtroopers would measure the mass  of  the
Falcon increasing more and more as it traveled closer to the speed of light.
If we want to accelerate the ship to one-fifth c, four times the velocity of
the exhaust, then we need about 57 times the mass of the ship in  fuel.  The
Falcon would look more bloated than Jabba the Hutt.

     And that's just And that's just to accelerate  one  time!  We  need  an
equal amount of fuel to slow down when we  reach  our  destination,  and  if
we're smuggling contraband, we may need to speed up and slow down many times
to avoid those pesky "Imperial entanglements." But what if we didn't need to
carry all our fuel with us? An idea introduced by Dr. Robert Bussard in 1960
is to build a ship that can scoop hydrogen out of interstellar space and use
it as fuel for fusion. The main problem here is that the density of hydrogen
out in space is very  low,  with  an  average  of  only  one  submicroscopic
hydrogen atom swimming in a cube one-half inch on a side.

     And as we know, we need lots of hydrogen to accelerate our  ship  using
fusion. So we'd need a huge scoop miles across to gather up even the tiniest
quantities of fuel. This huge scoop would substantially increase the mass of
our ship. And if we did make the scoop huge enough to scoop  up  significant
quantities, then the hydrogen in space would provide  a  resistance  to  the
forward momentum of the ship, like flying into a headwind. So we'd  need  to
work even harder to accelerate.

     Most scientists agree this isn't a practical method.  Even  us,  fusion
might be useful for small-scale,  relatively  low-speed  transportation  and
maneuvering , such as between planets within a single  solar  system  or  in
dogfights above the Death Star. But for  long  journeys  we  need  something
better. The helium exhaust from fusion can travel at up to one-twentieth the
speed of light. Could some other method shoot material out the back  of  the
ship at closer to the speed of light? The best possibility is a method  that
has long been popular  in  science  fiction  ,  the  mixing  of  matter  and
antimatter.

     Yes, antimatter does exist. The two major theories of physics,  quantum
mechanics and the theory of relativity, suggest that  each  particle  has  a
mirror-image antiparticle equivalent, and those antiparticles have  actually
been found. Antiparticles have the same mass and amount  of  spin  as  their
particle counterparts, but carry opposite electric charges and a  few  other
opposite characteristics.  For  example,  an  antielectron,  also  called  a
positron, has the same mass as an electron, but carries  a  positive  charge
instead of the electron's negative one. Positrons were discovered in 1932 in
cosmic rays, streams of high-energy particles that  constantly  bombard  the
Earth. Since then, antiprotons have also been observed. Antiparticles in and
of themselves are no different than what we consider regular particles.

     If the entire universe were made of antiparticles, life would be pretty
much the same. It's when particles  meet  antiparticles  that  we  run  into
trouble-or  opportunity.  The  particle  and  antiparticle  can   completely
annihilate each other, releasing two high-energy photons. Unlike fusion,  in
which only 1 percent of the mass is converted into energy, here  potentially
100 percent of the mass of the particle/antiparticle pair can be transformed
into energy, creating an intense burst of radiation. Why does the mixture of
matter and antimatter release more  energy  than  nuclear  fusion  or  other
processes? If E = mc2, why can't we completely free the energy in any mass?

     In any such reaction, certain  quantities,  such  as  charge,  must  be
conserved, meaning the  totals  must  be  the  same  before  and  after  the
reaction. In most reactions, this prevents  mass  being  entirely  converted
into energy. But with matter and  antimatter,  since  these  quantities  are
opposite and so carry a net value of zero, the particles can  be  completely
annihilated and all quantities conserved  .  As  the  resulting  high-energy
radiation shoots out the back of the spaceship at the speed  of  light,  the
ship would be propelled  forward.  You  may  be  wondering  how  photons  of
electromagnetic radiation can propel the ship forward. If  photons  have  no
mass, then isn't their momentum-the mass times the velocity-zero?

     No. Since mass and energy are  equivalent,  the  energetic  photons  do
carry momentum, equal to their energy divided  by  the  speed  of  light.  A
flashlight aimed out the back of  your  spaceship  could  similarly  provide
momentum, though it would  be  infinitesimal.  The  radiation  generated  by
matter/antimatter annihilation would have much higher momentum. In  fact,  a
pound of antimatter fuel can provide as much energy as one hundred pounds of
fusion fuel. To accelerate the ship to .99 c, you would need  only  thirteen
times the mass of the ship in fuel. Dr. Miguel Alcubierre, a  researcher  at
the Max Planck Institute for Gravitational  Physics  in  Pottsdam,  Germany,
agrees that "Matter/antimatter annihilation would be the most efficient  way
to achieve those speeds." So why don't we just gather up the antimatter  and
fire up the engines?

     Matter fills our galaxy, and antimatter seems to  appear  only  rarely,
through radioactive decay, particle collisions,  or  a  few  other  physical
processes. Scientists are now researching why the  universe  seems  made  of
matter far more than antimatter. While the Big Bang most likely created both
matter and antimatter,  no  antimatter  seems  to  have  survived  from  the
beginnings of the universe . Apparently, for some  unknown  reason,  a  tiny
inequality between the number of particles and antiparticles  arose  in  the
first fractions of a second after the Big Bang.

     For every one billion antiparticles , there were one  billion  and  one
particles. The one billion antiparticles and one billion  particles  quickly
annihilated each other, leaving two billion photons of  radiation  and  only
one surviving particle on the  battlefield.  That  surviving  particle,  and
those like it, formed all the  matter  in  our  universe.  Even  though  our
neighborhood is short on antimatter, we still might be able to  use  it  for
fuel. We now have the ability to create antiparticles, and  even  antiatoms,
using particle accelerators. Protons are accelerated and shot at  a  target,
and the collision creates antiprotons. Just  one  milligram  of  antimatter,
combined with one milligram of matter, can produce as  much  energy  as  two
tons of rocket fuel.

     This sounds very impressive; however with current techniques,  it  will
take 200,000 years to create one milligram of antimatter. And the cost  will
be-well, more wealth than you can imagine. If that isn't enough, it actually
takes much more energy to create antimatter than we  get  from  annihilating
the antimatter with matter. But if those in  the  Star  Wars  universe  have
developed a quicker, easier, and cheaper method of creating antimatter, this
could be a good method of near-light-speed travel. This may  be  the  method
used by the movies' spaceships when they are  fighting  or  traveling  short
distances. As we discussed  at  the  beginning  of  this  section,  however,
near-light-speed travel is just not good enough.

     To get us quickly across great distances, we need more radical  methods
of travel. Yet how can we break the speed limit? The answer comes  from  the
very theory that set the limit. Einstein's special theory of relativity  was
designed to explain what happens only under very specific circumstances;  in
particular, what happens when we travel at a constant  speed  and  are  away
from any  strong  gravitational  fields.  Einstein  chose  these  conditions
because they made the theory  easier  to  formulate.  After  completing  the
special theory of relativity, though, Einstein  went  on  to  consider  what
happens outside those specific circumstances, when we  are  accelerating  or
decelerating, or when we're  traveling  near  strong  gravitational  fields.
Einstein's general theory of relativity describes what happens in this wider
range of circumstances, and so, as Dr. Michio Kaku, professor of theoretical
physics at the City University of New York, says, "The general theory trumps
the special theory."

     The general theory reveals the universe is an even more  bizarre  place
than the special theory implies. While the special theory shows  that  space
and time are interconnected, the general theory shows that mass  and  energy
are also  connected  to  space  and  time.  This  opens  up  a  universe  of
possibilities, ways in which we might use mass or energy to manipulate space
to our own ends. Marc Millis, leader of the breakthrough propulsion  physics
program at NASA, explains that general relativity allows us to  "play  games
with space-time. The trick around special relativity, and the  speed  limit,
is that with general relativity you  can  warp,  fold,  distort,  or  expand
space-time."

     Whether any method  of  faster-than-light  travel  might  someday  work
remains speculation, however recent theories suggest there may  be  ways  to
break the speed limit-or at least work around it. Back when the  first  Star
Wars movie came out, scientists would not have  welcomed  such  speculation.
But Dr. Matt Visser, research associate professor at  Washington  University
in St. Louis, points out that within the last  ten  years,  "The  relativity
community has started to  think  about  what  would  be  necessary  to  take
something like warp drive or wormholes out of the realm of science fiction."
Might we soon be making the jump into hyperspace?



     A GALACTIC PIT STOP?


     The main problem with propulsion  is  getting  the  fuel  we  need  and
dragging it around with us. In our galaxy, fuel is not floating conveniently
out in space where we can simply pull over for a fill-up. But what if, in "a
galaxy for, far away," it were? If interstellar hydrogen was more plentiful,
Dr. Bussard's idea to scoop that hydrogen up to fuel fusion engines might be
more practical. Or if antimatter were easily available, Han Solo could  have
a free source of concentrated energy. Is it  possible  that  another  galaxy
might have conditions that make interstellar travel much easier than  it  is
in our Milky Way?

     Actually, we don't have to leave our galaxy to find  plentiful  sources
of fuel. Near the center of our own galaxy we can find both dense clouds  of
interstellar hydrogen and  plumes  of  antimatter.  Our  galaxy  is  a  huge
spinning disk of stars, planets, gas, and dust 130,000  light-years  across.
Among the 100 billion galaxies in our universe,  the  Milky  Way  is  fairly
average, with about 200 billion stars. The Milky Way is a spiral galaxy,  as
70 percent of all galaxies are, with long arms of stars and dust curling out
from the galactic core. Our solar system  is  25,000  light-years  from  the
core, out on one of the spiral arms. Conditions on the arm are fairly  tame.
Yet as we move toward the  galactic  center,  conditions  become  much  more
dangerous and unpredictable.

     The disk of the galaxy bulges in the center with a dense conglomeration
of stars several thousand light-years across. As we move through this region
toward the galactic core, we find clouds of  dust  one  hundred  times  more
dense than in our neighborhood, pockets of free fuel. Stars whizz about  the
galactic center at a dizzying one-half the  speed  of  light,  packed  in  a
million times more densely. Torrents of high-energy radiation blast out from
the core, and intense magnetic fields  crisscross  the  area.  At  the  very
center, the dynamo driving all this activity is  a  black  hole  or  several
black holes about two million times more massive than the sun.  These  black
holes are believed to be the source of antimatter discovered just last year.
Dr. William Purcell of Northwestern University found a  plume  of  positrons
shooting out from the center of our galaxy.

     This discovery suggests there may be other antimatter  sources  in  the
universe. If a source of antimatter were close to us, and we could develop a
safe way of harvesting it, we might use it as a fuel  to  power  our  ships.
Since we already have safe ways to store the  small  amounts  of  antimatter
we've created, harvesting and storing the antimatter seems like something we
could do.

     The difficult part would be  surviving  annihilation  if  there  was  a
natural source of antimatter nearby. Dr.  Visser  thinks  that  could  be  a
problem. "You don't want to find 3V too much around, or that would make life
difficult in that vicinity." Curiously, scientists have found no evidence of
large quantities of antimatter in the galaxies nearest to us. Yet  the  jury
is still out.

     Theoretical  astrophysicist  Michael  Burns  believes,  "It's  possible
many-maybe all-galaxies have a matter -antimatter source at their cores." If
dense clouds of  hydrogen  and  antimatter  exist  in  the  neighborhood  of
galactic cores, could we theorize that the Republic and Empire of Star  Wars
are closer to the core of "a galaxy far, for away" than we are  to  our  own
galactic core? The core itself would obviously be a  very  unfriendly  place
for life, with lethal  radiation,  ten-billion-degree  temperatures,  and  a
black hole whose tidal forces can rip stars to  pieces.  Dr.  Burns  agrees.
"Within the central parsec of a galaxy, it would be hostile." But how  about
just beyond that region? Marc Millis believes denser neighborhoods of  stars
may offer an advantage : encouraging the inhabitants to develop interstellar
travel. "If the nearest star were only one light-year away instead  of  over
four light-years away, as it is for us, that might  provoke  an  intelligent
civilization to make the investment necessary to  send  a  probe  there  and
eventually journey there." Dr. Visser agrees. "If a civilization set up shop
in a globular cluster or nearer the core of the  galaxy,  distances  between
stars would be much smaller, and that would already be a big help." Yet such
a neighborhood might not be the healthiest for humans either. "If  you  have
too many stars too close together," Dr. Visser  says,  "you  run  additional
risks.

     A nova could destroy your planet before  you  can  get  a  civilization
formed." So the best place to start a Republic might be  in  a  neighborhood
much like ours. It doesn't look like much, and there's no free fuel, but  we
have to start somewhere.



     "WHEN YOU CAME IN HERE, DIDN'T YOU HAVE A PLAN FOR GETTING OUT?"


     When Han Solo takes the Millennium Falcon from Tatooine to Alderaan, he
makes the "jump to hyperspace," a strange region of stretched-out  starlight
that seems to allow  extremely  rapid  travel  over  great  distances.  This
technique must allow  Han  to  "play  games"  with  space-time,  warping  or
distorting it to circumvent the light-speed limit. One of the weird  methods
of travel suggested by Einstein's general theory of  relativity,  which  may
very well be the one used by Han Solo, is to  create  a  shortcut  from  one
point to another. This tunnel-like shortcut, called a wormhole,  allows  you
to get from your origin to your destination  without  traveling  the  entire
distance between.

     Einstein established that we live in  and  travel  through  a  flexible
four-dimensional space-time, with three dimensions of space and one of time.
Anything that folds, expands, or distorts spacetime might be  made  to  work
for us, to help us travel through it more quickly.  How  can  space-time  be
distorted? Einstein revealed  that  any  mass  distorts  it.  We  call  that
distortion gravity. Imagine you are about to skydive out of a  plane  twelve
thousand feet up. When you step out of the plane, the force  of  gravity  is
going to pull you toward the massive Earth below.

     But how does your body know that the Earth is there? Exactly  how  does
the Earth exert this force on your body? The answer provided by the  general
theory of relativity is  that  the  mass  of  the  Earth  actually  distorts
space-time, and that distortion pulls your body downward. Since it's  pretty
impossible for most of us to visualize four-dimensional space-time,  instead
imagine we live in two dimensions. Space would then be like  a  huge  sheet.
Now imagine this sheet is made of a stretchy material like a  trampoline.  A
mass, like a bowling ball, placed on this sheet will create a depression. If
you step onto this sheet, you will slide down toward the bowling ball.


     Similarly, the Earth, placed on this sheet, will create  a  depression.
If you step out of a plane twelve thousand feet 

    <MISSED PART!!!!> 

    down the  sheet to the bowling ball. This is   exactly   what  Einstein 
described in his  general theory of relativity.    The heavier the mass, the 
greater  the distortion  of space-time. The   mass will sink lower and lower 
into the  sheet,  creating  a deeper    and deeper depression, and a steeper 
and  steeper  curvature  on  the sides of the depression.

     Now, when I said to imagine space as a sheet, you probably  imagined  a
flat sheet stretching as far as you could see. But as we are  learning,  the
sheet will not remain flat. It will be subject to all sorts  of  curves  and
distortions, from every mass in it. So now imagine that  this  sheet  has  a
large-scale  curve  to  it,  like  a  bedsheet  hanging  out  to  dry  on  a
clothesline, half on one side and half on the other.  On  one  side  of  our
sheet, a huge mass creates a deep depression. Now walk around to  the  other
side of the clothesline. On the comparable point on this side of  the  sheet
is  another  huge  mass,  creating  another  deep  depression.   These   two
depressions could then theoretically touch and merge, creating a tunnel from
one point on the sheet to the other.

     Without this tunnel, the shortest distance between these two points  is
to travel the full distance up to the clothesline and down the  other  side.
But with this tunnel, we now have a shortcut that could  theoretically  take
us very quickly from one point to another a great distance  away.  Dr.  Kaku
explains, "When your teacher told you that the shortest distance between two
points is a line, that was wrong. The shortest distance is a wormhole."  The
tunnel does not exist in regular space, since regular space, in this  model,
is just the two-dimensional sheet.

     The  wormhole  exists  in  an  additional  dimension,  outside  regular
space-time as we know it. Such additional dimensions are called  hyperspace,
and we would  travel  through  the  tunnel  in  hyperspace  to  get  to  our
destination, just as Han Solo does. Perhaps when Han Solo prepares  for  the
jump to hyperspace, he is actually creating  a  wormhole  from  his  current
location to his destination that will serve as an easy shortcut. Using  such
a shortcut, he could potentially travel from one star to another in a matter
of hours.  Dr.  Alcubierre  believes  that  in  Star  Wars  they  are  using
"something similar to wormholes.  They  jump  from  one  place  to  another.
Wormholes are portals from one place to another far away."

     While we've been visualizing  the  wormhole  as  a  drainlike  hole  in
two-dimensional space, if we translate this back into the three- dimensional
space in which we live, the wormhole would actually look like a sphere. What
would Han and the others see as the wormhole opened? Dr.  Visser  says,  "If
anything, all they would see is a region of space that looked like a  window
that opened up to a distant region of the galaxy."

     Although wormholes have not yet been observed, they  are  theoretically
possible. Unlike black holes, which suck in matter and light and  don't  let
any out,  wormholes  can  potentially  be  two-way  transportation  systems,
allowing material to both enter and exit. As Marc Millis says, "A black hole
is like falling down a well where there's a definite bottom; a  wormhole  is
more like a tunnel."

     There are several problems with wormholes, though. If we did manage  to
find one, the two "mouths" of the wormhole  would  most  likely  not  be  in
convenient locations for us. Having one end open  in  my  backyard  and  the
other in Harrison Ford's backyard is not terribly likely, much  as  I  might
wish it. In the off chance that did arise,  though,  we'd  be  in  for  more
trouble. It seems that, even theoretically, all  wormholes  are  unstable  ,
forming-if they form at all-only transiently.

     The two depressions in the sheet meet and create a tunnel only  for  an
infinitesimal fraction of a second; then  the  tunnel  pinches  closed.  The
depressions become separate before anything, even light, has  time  to  pass
through them. Worse yet,  anything  caught  inside  at  the  moment  of  the
pinch-off would be crushed in a way that would  make  getting  strangled  by
Darth Vader seem pleasant by comparison . "Do they naturally exist  for  any
time span in which we could see one?" Dr. Visser asks  himself.  "I  wish  I
knew the answer to that."

     And we needn't be caught at the  pinch-off  to  be  killed.  Since  the
deformity of space-time is so great around the wormhole, tidal gravitational
forces would most likely kill any human attempting to traverse the wormhole.
We talked  about  tidal  forces  in  connection  with  planets.  The  strong
gravitational fields of stars can create tidal forces,  in  which  the  near
side of the planet feels a significantly greater attraction to the star than
the far side. It's essentially the same thing with humans.  If  you  imagine
yourself dropping feet first into the wormhole, your  feet,  closer  to  the
wormhole, would be subject to a greater gravitational attraction  than  your
head, and you'd be pulled into a long, thin string. The  size  of  naturally
occurring wormholes might not be terribly convenient either.

     "I think they are going to be very small," Dr. Visser says, "much, much
smaller than atoms." Finding out what's on the  other  side  of  these  tiny
wormholes isn't going to be easy. "Imagine trying to look through a  pinhole
smaller than an individual atom," Dr. Visser explains. "Ordinary light has a
wavelength much larger than an atom. So we can't shine a light through it. I
think that's a bit of bad  news  there.  We  may  get  lucky  and  find  one
accidentally that's large."

     Dr. Alcubierre suggests that instead of searching for a large wormhole,
we might take a small one and find a way to enlarge it. Without at  least  a
small one to get us started, though, he admits, "It would be hard  to  think
of how to make one in the first place. We'd have to  punch  a  hole  through
space. I don't think we'd know how to start." But physicist  Kip  Thorne  at
the California Institute of Technology may have found the place to start. He
discovered a solution to Einstein's equations that  allows  for  a  wormhole
that is free of destructive tidal forces and will not pinch closed. This  is
called a "traversable" wormhole. The trick is that the tunnel or "throat" of
the wormhole can be held open if we put something  into  the  wormhole  that
pushes gravitationally outward on its walls, preventing them from collapsing
inward.

     Since gravity, as we  know  it,  always  draws  objects  together,  any
material that pushes objects apart, that has in essence repulsive gravity or
antigravity  (like  the  device  Boba   Fett   uses   to   transport   Han's
carbonite-frozen form), would have to be unlike  anything  we  know  of.  In
fact, some observers would measure this material as having negative  energy,
something else we've never seen before.

     Such material is called "exotic matter." Does exotic matter exist?  Dr.
Visser points out that a few years ago, the idea would have been  laughable.
"We would have said, 'Negative matter? That tells us absolutely we can't  do
these things.' " Yet  quantum  mechanics,  the  theory  that  describes  the
universe at the subatomic level, suggests that exotic matter does exist. The
existence of such negative energy was first  predicted  by  Dutch  physicist
Henrik Casimir in 1948. In 1958, the effect he predicted was observed.

     "That force has been measured," Dr. Alcubierre  says.  "This  thing  is
real." To understand how exotic matter might exist, we need to take a little
detour before we return to wormholes. But this detour is important not  only
for the formation of wormholes, but for antigravity, the Force, and a  whole
host of other possibilities. Let's  see  how.  One  of  the  most  fantastic
realizations of recent years is that the vacuum of empty space is not really
empty. The Heisenberg uncertainty principle,  one  of  the  main  tenets  of
quantum mechanics , tells us that tiny energy fluctuations  may  occur  that
exist for such infinitesimal  time  intervals  that  they're  impossible  to
measure .

     I'll explain this in more detail in Chapter 5, but basically the  issue
is this: when we measure extremely small, or quantum, quantities, the simple
act of measuring disrupts the system. Thus the amount of information we  can
gather is limited. And if we can't know exactly what's  going  on  at  these
very small levels, then all sorts of things can be going on. What do we care
if tiny energy fluctuations exist for such short  times?  Because  sometimes
this energy may be great  enough  to  create  a  particle-antiparticle  pair
spontaneously out of empty space.

     The pair annihilate each other almost instantly and disappear back into
the vacuum before we're able to detect them.  (And  you  thought  the  Tooth
Fairy was hard to believe.) Such particles are called  "virtual  particles,"
since they can never be measured directly . But since we can't detect  them,
physical laws such as conservation of energy, which would normally not stand
for something to be  created  from  nothing,  remain  satisfied.  Scientists
envision space on  this  tiny  scale  to  be  a  bubbling  foam  of  quantum
fluctuations, in which particles, antiparticles, and even quantum  wormholes
are continuously popping in and out of existence. On the quantum scale,  the
fabric of space-of reality-actually breaks down.

     Physicist Heinz Pagels, author of The Cosmic Code,  compares  space  to
the ocean. "Over long distances the vacuum appears  placid  and  smooth-like
the ocean which appears quite smooth when we fly high  above  it  in  a  jet
airplane. But at the surface of the ocean, close up to it in a  small  boat,
the sea can be high and fluctuating with great waves." If we  can't  measure
these particles, though, how do we know they exist? Scientists such  as  Dr.
Casimir have predicted the effect these  virtual  particles  would  have  in
various situations, and those effects have been measured. So  we  know  that
these undetectable, virtual particles do exist.

     In fact, some scientists believe that the Big Bang  out  of  which  our
universe formed was triggered by a quantum fluctuation of  some  kind.  When
these fluctuations occur near a strong curvature in space-time, such as near
a wormhole, they may lead to the creation of negative  matter,  matter  that
has the repulsive gravitational force we  need  to  hold  open  a  wormhole.
Imagine that a particle/ antiparticle pair  pops  into  existence  near  the
gravitational depression caused by  a  wormhole.  Normally  the  pair  would
annihilate each other and disappear. But what happens if one member  of  the
pair is sucked down by gravity into the wormhole, while the other happens to
escape into space? The surviving particle then is not annihilated,  and  can
theoretically be detected. It's no longer a virtual  particle,  but  a  real
particle. This is potentially devastating to physics.

     Remember,  conservation  of  energy  was  only  satisfied  because  the
particles weren't around long enough to detect. Now it  appears  we  have  a
particle, a bit of energy, created from nothing. Physicists  have  found  an
interesting way to keep  their  old  laws  satisfied.  Since  the  surviving
particle carries a certain  positive  energy  ,  then  we  must  assume  the
particle that fell into the wormhole had  negative  energy.  That  way,  the
total energy would still be zero. This particle with  negative  energy  then
qualifies as the "exotic matter" needed to hold open the wormhole.

     Is this exotic matter actually produced around  a  wormhole?  We  don't
know. We still haven't discovered a single wormhole.  Even  if  it  is,  the
exotic matter created might not be enough to do the job. Or it might kill us
as we pass through the wormhole. But  at  least  this  theory  provides  one
possible source  of  exotic  matter.  Whether  we  might  manufacture  large
quantities of exotic matter to create artificial wormholes is also  unknown.
"There's no proof that it can't be done," Dr. Alcubierre says. "It may  just
be that we haven't figured out yet how to do it.

     Yet it's very doubtful that  we'll  be  able  to  produce  it  in  such
quantities that we'll ever be able to  do  anything  useful  with  it."  Dr.
Visser has calculated that to make a one-meter-diameter wormhole,  we  would
need to convert into negative energy a mass equal to that of  Jupiter.  "You
need about minus one Jupiter  mass  to  do  the  job.  Just  manipulating  a
positive Jupiter mass of energy is already pretty freaky,  well  beyond  our
capabilities into the foreseeable future."

     Since exotic matter, as far as we know, appears  only  on  the  quantum
level, it would be very difficult to amass an amount this great. Could we do
it? "Possibly, yes," Dr. Visser says. "Probably, in  the  immediate  future,
no. An arbitrarily advanced civilization might be able to do  these  things.
We, on the other hand, are not arbitrarily advanced."

     The Star Wars Republic and Empire, however, are. Dr. Kaku believes that
a galactic civilization like that in Star Wars would  have  learned  how  to
access huge quantities of energy. He  uses  astronomer  Nikolai  Kardashev's
method for categorizing future civilizations.

     A Type I civilization is planetary.  It  controls  the  forces  on  its
planet, manipulating the weather and earthquakes, and  gaining  energy  from
them. It has colonies on other planets within the solar system.

     A Type II civilization is stellar. Solar flares are its energy  source,
and it has begun to colonize neighboring solar systems.

     A Type III civilization is galactic. It uses the power of  billions  of
stars, black holes, and supernovae, and can manipulate space-time.

     While Dr. Kaku believes we are a Type 0 civilization ,  he  finds  Star
Wars's Republic and Empire to be Type III. Comparing the energy of a  planet
to that of a star to that of a galaxy, Dr. Kaku approximates that the energy
available to a civilization increases ten billion times over with every step
up this scale. "How they'll access this energy," Dr. Kaku admits,  "I'm  not
sure. But they will access it." This gives the Republic a lot of  energy  to
play with. Dr. Visser believes that access to those huge amounts  of  energy
would allow the Star Wars civilization to produce  exotic  matter.  "If  you
think of some of the things going on in Star Wars, it's likely they could do
this."

     Exotic matter will only help keep a wormhole open,  though.  To  travel
from Tatooine to Alderaan, Han Solo still needs to create  the  wormhole  in
the first place. Armed with exotic matter, might those in "a galaxy far, far
away" have come up with some clever way  to  open  traversable  wormholes-to
"punch holes through space"-at will? It's not yet clear whether  this  might
be  possible  or  not.  To  create  huge  depressions  and  deformations  in
space-time requires we manipulate huge  masses  and  huge  energies.  "We've
found it's going to be extremely difficult if not  downright  impossible  to
build these things," Dr. Visser admits. "They will require huge  amounts  of
energy."

     This hasn't stopped physicists from proposing a variety of  methods  to
create wormholes, though all remain unproven and pose many problems. As  Dr.
Kaku says, "Every physicist has his own design. It's like cave  men  saying,
'Wouldn't it be nice to have a car?' But they don't have  any  gas.  We  can
design machines, but we don't have the gas." If one  of  these  designs  did
work, though, physicists in Star Wars's galactic Republic, according to  Dr.
Kaku's calculations, should have all the gas they need.



     GETTING SOMETHING FROM NOTHING


     While quantum fluctuations might  help  produce  stable  wormholes  for
interstellar travel, some scientists wonder if these fluctuations  might  be
put to other uses. "Nothing has a little bit of energy," Dr. Kaku says, "and
it's all around us." Earlier, we struggled to find free fuel  deposits  that
we could pick up along our interstellar travels. If space itself is  foaming
with energy, then, couldn't we harness that energy to fuel  a  ship?  Rather
than scooping hydrogen out of space, we would use space itself as fuel. Just
as with hydrogen or antimatter, one key issue is how powerful the fuel is.

     Unfortunately , this vacuum energy, also called the zero-point  energy,
remains poorly understood, and its magnitude is  still  a  matter  of  great
controversy. While the fluctuations we've been  discussing  are  tiny,  they
permeate all of the universe, and exactly what  they  would  add  up  to  be
remains  uncertain.  Quantum  physicists  calculate  a  vacuum   energy   so
incredibly huge that it would far overwhelm the energy embodied in  all  the
mass in the universe. In fact, it's ten billion trillion  trillion  trillion
trillion trillion trillion trillion trillion trillion  times  greater.  Marc
Millis considers this view: "I've read that there is enough  energy  in  the
volume the size of a coffee cup to boil away the Earth's oceans-if true  and
tangible, this could be quite useful." It could certainly help fill  up  the
gas tanks on the Falcon. "The amount of energy is so huge,"  Dr.  Alcubierre
says, "if we could access it, it would solve all our problems."

     Yet cosmologists believe that the vacuum energy cannot be  that  great,
or we wouldn't be here to have  this  discussion.  Energy,  they  argue,  is
equivalent to mass, and mass creates a gravitational  attraction  .  If  the
vacuum energy was huge, the resulting attractive force would have  collapsed
our universe into a huge black hole in its first moment of  existence.  Some
cosmologists argue that this vacuum energy  may  be  repulsive  rather  than
attractive. But if that is so, a vacuum energy of the  magnitude  calculated
would have such a strong repulsion that it would  have  blown  the  universe
apart in its first instants, so far apart that not  even  atoms  would  have
formed.

     So, these scientists reason, the vacuum energy must  be  much  smaller,
though they  haven't  yet  figured  out  why.  Dr.  Steven  Weinberg,  Nobel
prize-winning physicist at the University of Texas, asserts that the  vacuum
energy in a volume the size of the Earth is no more than the energy  we  get
from a gallon of gasoline . Han  might  as  well  go  back  to  scooping  up
hydrogen atoms. These days, the majority of scientists feel a  small  vacuum
energy is more likely, but a great deal of  uncertainty  remains.  We  still
don't know whether these vacuum fluctuations create an attractive  force,  a
repulsive one, or neither. In addition, we don't know if we'll ever be  able
to access this energy.

     But some scientists remain hopeful that the vacuum energy can be put to
good use and are developing techniques to tap into it. They  speculate  that
we may someday learn how  to  "engineer"  the  vacuum,  as  Dr.  T.  D.  Lee
describes it, putting "empty" space to work  for  us.  Even  if  the  vacuum
energy is not terribly large, it may still offer ways to make  space  travel
easier and faster.

     Dr. Hal Puthoff, Director of the  Institute  for  Advanced  Studies  at
Austin, theorizes that quantum fluctuations may be the cause of inertia. His
theory remains speculative and extremely  controversial,  yet  it  offers  a
fascinating possibility that could be very helpful to Han Solo.  Inertia  is
the quality of a body at rest to stay at rest,  and  a  body  in  motion  to
remain in motion. It's what throws you back against your seat when you press
down on the gas, and what throws you forward when you press  on  the  brake.
This resistance to acceleration is exactly what we're  fighting  against  in
space travel. We need to accelerate the Falcon to high  speeds,  and  to  do
this we must apply a force of some kind, through propulsion  or  some  other
means.

     The greater the mass of an object,  the  more  force  is  necessary  to
accelerate it, as shown in Newton's classic equation, F = ma. This  equation
reflects what we observe, but doesn't explain it. And in the  three  hundred
years since Newton wrote his laws, we still haven't explained  it.  What  is
the underlying cause for the phenomenon? Exactly what causes this resistance
?

     Most scientists simply accept  inertia  as  an  intrinsic  property  of
matter. In the near future, though, we may prove that  it's  something  else
entirely. Imagine yourself standing in a subway  car  that  has  stopped  at
Times Square station. The doors close, and the subway  moves  ahead.  As  it
accelerates, you stumble backward, pushed back by inertia. Yet what  exactly
is pushing you?

     Dr. Puthoff and colleagues have  theorized  that  quantum  fluctuations
create an electromagnetic field, called the zero-point field, that causes  a
resistance on every particle within an accelerating body. "If you stick your
hand in a pool of water and try to accelerate  it,"  Dr.  Puthoff  explains,
"you feel a drag force back on your  hand.  This  is  the  same.  If  you're
standing on a train that takes off with a jerk and suddenly you end up  flat
on your back, it's as if a two- hundred-pound person knocked you  down.  The
train accelerated you through  the  zero-point  field,  just  as  your  hand
accelerated through the water." While water and air  produce  a  drag  force
even if you travel through them at constant velocity, the  zero-point  field
only produces a drag force  if  your  velocity  changes.  According  to  Dr.
Puthoff's  calculations,  which  are  simplified  to  make   the   equations
manageable, this electromagnetic drag force, amazingly, is  proportional  to
the acceleration of  the  body  and  exactly  obeys  the  equation  F  =  ma
established by Newton so long ago. Many scientists remain skeptical  of  Dr.
Puthoff's theory, though. Dr. Alcubierre finds the calculations "fine,"  but
remains skeptical about the conclusions.

     He believes Dr. Puthoff has proven that the zero-point  field  produces
something similar to inertia . "It's a big jump to say that it is  inertia."
If Dr. Puthoff's  theory  is  true,  this  is  a  bizarre  concept:  virtual
particles are  exerting  a  force  on  you!  Or  to  be  more  precise,  the
electromagnetic forces of these virtual particles are  pushing  against  the
electromagnetic forces in the particles that make up your body.  If  we  can
learn to control these quantum fluctuations, we can  potentially  reduce  or
eliminate inertia, which would be in essence like  reducing  or  eliminating
the mass of an object-which would make accelerating  it  to  high  speeds  a
whole  lot  easier.  Remember,  one  of  the  problems  of  accelerating  to
near-light speed was that the ship's mass  would  be  measured  to  increase
dramatically. If we could completely eliminate mass, we could  theoretically
travel at the speed of light, just like photons. Han talks about making  the
"jump to light speed."

     If the Falcon is somehow jumping to light speed, it  implies  a  nearly
instantaneous acceleration. The Falcon might be traveling along at 50  miles
per hour, and then suddenly it's traveling at 186,000 miles per second.  Let
BMW try to beat that acceleration!  The  Falcon  might  accomplish  this  by
temporarily eliminating inertia. Just eliminating it for  a  fraction  of  a
second could allow a  rapid,  effortless  acceleration,  after  which  point
inertia could return and  the  Falcon  could  cruise  at  a  constant,  high
velocity. Such a technique would  also  allow  humans  to  survive  such  an
acceleration, and so solve another problem of space travel. It's no  problem
for Han to accelerate the Falcon from zero to 60  miles  per  hour  in  five
seconds. Inertia will push him slightly back in his seat.  But  accelerating
from zero to 186,000 miles per second in five seconds will push Han back  so
forcefully that he'll become a splat on that fine vinyl upholstery.

     The speed of light is so fast, that to accelerate to  it  safely  would
take months! We measure acceleration  in  g's,  with  one  g  equal  to  the
acceleration caused by Earth's gravity-the acceleration of  falling  objects
on Earth. The reason we measure acceleration in terms of gravity is  because
the two have the same effect. The  equivalence  principle  states  that  the
gravitational force on an object is equivalent to the inertial force  on  an
object undergoing a comparable acceleration. Just as gravity pushes you down
against the Earth, inertia pushes you back against your seat.

     Imagine you are standing in an elevator at rest on the ground floor  of
the Empire State Building. The doors close.  As  the  elevator  accelerates,
inertia pushes you downward against the  floor  of  the  elevator,  just  as
gravity pushes you downward against the surface of the  Earth.  Imagine  now
that you are in an elevator out in deep space. If the  elevator  accelerates
upward at exactly 32 feet per second2, the acceleration  caused  by  Earth's
gravity, you would be unable to tell the difference  between  this  inertial
force and the gravitational force you'd feel if you were simply standing  in
a stationary elevator on Earth. We experience higher or lower g forces  when
we are rapidly changing speeds or directions. Normal humans can withstand no
more than 9 g's, and even that for only a few seconds.  When  undergoing  an
acceleration of 9 g's, your body feels nine times heavier than usual,  blood
rushes to the feet, and the heart can't  pump  hard  enough  to  bring  this
heavier blood to the brain. Your vision  narrows  to  a  tunnel,  then  goes
black.

     If the acceleration doesn't decrease, you will  pass  out  and  finally
die. The Air Force's F-16 can produce more  g's  than  the  human  body  can
survive. We're forced to limit the acceleration of planes and spacecraft  to
a level humans can survive. If we need to accelerate for  extended  periods,
the level we can withstand is even lower. We can withstand 5  g's  for  only
two minutes , 3 g's for only an hour. For  the  sake  of  argument,  though,
let's try to tough it out at 3 g's for a little longer. For Han to take  off
from Mos Eisley and accelerate at 3 g's to half the  speed  of  light  would
take him two and a half months. Hardly the makings of an exciting movie.

     Even at 9 g's, it would take him nineteen days to reach half the  speed
of light, though he'd be dead long before the ship reached that speed. Since
Star  Wars  ships  are  constantly  undergoing   rapid   accelerations   and
decelerations, they must have found some way to solve this problem.  Perhaps
they have learned to manipulate inertia as Dr. Puthoff suggests. Of  course,
the force that makes us stumble back as the subway car  accelerates  doesn't
seem completely conquered on the Falcon. In The  Empire  Strikes  Back,  the
Falcon's jump to hyperspace throws Artoo across the deck and into  the  open
engine pit. Perhaps some of Han's "special modifications" need a tune-up.



     WHY MAKE HAN GO TO JABBA, WHEN JABBA CAN COME TO HAN?


     Assuming g forces haven't killed Han during one of his wild takeoffs  ,
he still needs a  faster-than-light  method  of  getting  from  Tatooine  to
Alderaan. A wormhole is one possibility. Another possibility is an ingenious
method proposed by Dr. Alcubierre. This method, which he calls "warp drive,"
was inspired by science fiction. "People in Star  Trek  kept  talking  about
warp drive, the concept that you're warping space. We already have a  theory
about how space can or cannot be distorted, and that is the  general  theory
of relativity.

     I thought there should be a way of using those concepts to  see  how  a
warp drive would work." And that's exactly what he  did.  From  our  earlier
discussion, we know that space-time curves and deforms in  the  presence  of
mass or energy. Space-time can actually do  even  more:  it  can  expand  or
contract. With the Big Bang, the space-time of  our  universe  expanded  out
from a single point. This doesn't mean that matter expanded out  into  empty
space; it means that space itself expanded, carrying matter  with  it.  It's
still expanding today. Scientists theorize that the shape  of  the  universe
may be a sphere in four dimensions, or a hypersphere. Let's avoid trying  to
think in four dimensions by comparing this to a simpler model.

     Picture our universe as the spherical surface of a balloon. The balloon
has tiny little galaxies drawn all over it. As the balloon is inflated,  all
galaxies move away from ours, as the space-time between  them  expands.  The
greater the distance between objects, the more expanding balloon is  between
them, and so the faster the distance between them increases. This is exactly
what we find when we measure the velocity of various galaxies. Space-time is
continuing to expand. If we're going to use this ability of space to  expand
or contract to help us travel, we need to know how quickly the expansion can
occur. Many scientists now believe that in the first fraction  of  a  second
after the Big Bang-the first billionth of a trillionth of a trillionth of  a
second, if you must know-space-time underwent a violent expansion at  speeds
greater than the speed of light!

     Yes, you heard me right. While within  space-time  nothing  can  travel
faster than the speed of light, space-time itself can travel, or expand , at
any speed. The rules of special relativity do not constrain it. This theory,
called  inflation,  suggests  that  the  observable  universe  is  only   an
infinitesimal portion of the entire universe, and that the great majority of
galaxies are so far away that the light from them hasn't had  time,  in  the
fourteen-billion-year lifetime of the universe, to reach us  yet.  In  fact,
those distant galaxies may even now be moving away from us faster  than  the
speed of light. Or from their point of view, we may be moving away from them
faster than the speed of light.

     We need to clarify the speed limit, then. A more precise way of  saying
it would be that nothing can travel locally faster than the speed of light.

     This is one time when an exception to the rule is a good thing.  Within
a region in which the expansion of space is negligible, we can't  travel  at
or above the speed of light. However  when  the  expansion  of  space  is  a
significant factor, anything is possible. Let's go  back  to  our  balloons.
Imagine a clean, deflated balloon. You draw two dots on the balloon one inch
apart. You then attach the balloon to  the  nozzle  of  a  helium  tank  and
rapidly inflate the balloon to full size. The two dots are now perhaps eight
inches apart. They have moved quickly away from each other. Yet each dot, in
itself, is not able to move and has not moved. Dr. Alcubierre suggests that,
similarly, one could travel great distances without really moving at all, by
warping space.

     Theoretically , after blasting his way out  of  Mos  Eisley,  Han  Solo
could design a space-time disturbance that would expand  the  space  between
the Millennium Falcon and Tatooine, making Tatooine recede many light  years
away, and contract the space  between  the  Falcon  and  Alderaan,  bringing
Alderaan close to the Falcon. The Falcon would essentially  be  pushed  away
from Tatooine and pulled toward Alderaan. As space  expands  behind  it  and
contracts  in  front  of  it,  the  Falcon  would  be  carried  toward   its
destination, like a surfer riding a wave.  How  fast  would  such  a  "wave"
travel?

     Dr. Alcubierre believes the wave  could  travel  with  an  "arbitrarily
large" speed. The only such wave that seems to have  occurred  naturally  is
the one we're riding now in the expansion of the universe. Since it may have
once traveled faster than the speed  of  light,  we  can  theorize  that  an
artificially created wave could similarly travel faster than light.  Outside
the region of the disturbance, observers would  measure  the  Falcon  moving
faster just as observing the balloon you would measure the two  dots  within
the disturbance, Han would within the  disturbance,  Han  would  not  travel
faster than the speed of light because light would also be carried along  on
the wave. Like the dot on the balloon, he would not perceive himself  moving
at all.

     One benefit of this technique is that Han wouldn't suffer from inertia.
Dr. Alcubierre confirms, "He wouldn't feel  any  acceleration,  wouldn't  be
squeezed against the back of his seat." Another benefit is that there  would
be no time dilation effect, as there is when one is traveling near the speed
of light. "You can have breakfast at home," Dr.  Puthoff  says,  "take  off,
have lunch at Alpha Centauri, and come back at dinner and still  be  talking
to your wife, not your great great grandchildren."

     And going into warp drive might look a lot like what we  see  when  the
Falcon makes the jump to hyperspace . "My guess is they would  probably  see
something very similar to that," Dr. Alcubierre says. "In front of the ship,
the stars would become long lines,  streaks.  In  back,  they  wouldn't  see
anything -just black-because the light  of  the  stars  couldn't  move  fast
enough to catch up with them." Using warp drive, Han  could  reach  Alderaan
very quickly  without  actually  going  anywhere.  Dr.  Robert  L.  Forward,
scientist and science fiction writer, calls it a "neat idea.

     Mathematically and physically solid. Just a  little  difficult  from  a
practical engineering point of view." So how would Han  pull  this  off?  To
warp space, he would need to manipulate huge masses and energies, just as we
discussed with wormholes. Dr. Forward stresses that "The  amount  of  matter
needed in front and behind the ship is enormous ." Han would also  need  the
same exotic matter with negative energy necessary to  hold  open  wormholes.
Remember that exotic  matter  creates  a  repulsive,  or  antigravitational,
effect. In this case, the exotic matter is necessary because  Han  needs  to
create a repulsive gravitational force  between  the  Falcon  and  Tatooine,
expanding space between them.

     The amount of negative  energy  required  is  similar  to  that  for  a
wormhole. Dr. Visser calculates that to  create  a  warp  bubble  one  meter
across, we'd need about the same amount of exotic matter as for  a  wormhole
one meter across: an amount equivalent to the mass of Jupiter. The theory of
inflation provides another indication that exotic matter does exist,  or  at
least that it did exist in the first fraction of  a  second  after  the  Big
Bang. Scientists believe its repulsive force may have been  responsible  for
the brief faster-than-light expansion of the universe at that time. We  have
one other problem to conquer in the use of warp drive. If our  ship  travels
faster than the speed of light, it is not able to affect the space in  front
of it.

     In essence, the ship zips past before space even "knows" it  is  there.
Thus the contraction of the space in front of the ship cannot arise from the
ship itself. We need some outside generators to create  the  contraction  in
front of the ship. Dr. Alcubierre explains,  "We  would  need  a  series  of
generators of exotic matter along the way, like a highway,  that  manipulate
space for you in a synchronized way."  The  spaceship  would  then  position
itself at the beginning of this highway, and the generators would create the
wave distortion of space, on which the spaceship would ride.

     Rather like a train in  a  subway  tunnel,  the  ship  itself  wouldn't
produce the energy, but would simply  ride  along  on  it.  This  use  of  a
"highway" set up ahead of time doesn't seem like what we see in  Star  Wars,
but perhaps with their advanced technology, they've found an easier  way  to
engineer a warp drive. The ability to warp space could also  be  used  as  a
defensive mechanism, to deflect enemy laser fire. The Falcon  has  deflector
shields, as do star destroyers.

     How might they work? As  we  know,  a  mass  creates  a  depression  in
space-time that draws  other  masses  to  it.  Since  mass  and  energy  are
different forms of the same thing, a depression in space-time can also  draw
a beam of energy toward it. For example, when light from a star passes  near
the sun, the sun's gravitational field  will  attract  the  light,  slightly
bending its course. This creates the opposite effect from what  we  want  to
occur. The Falcon's mass will actually slightly attract Imperial laser  fire
toward it. Not a good thing. The sun bends light by only  a  fraction  of  a
degree, though, so the effect from Han's ship will be infinitesimal.

     What we want to do  is  create  the  opposite  effect,  and  much  more
strongly. The opposite of an attractive depression is a repulsive bulge.  If
Han can warp space, he can create this anti-gravitational bulge. As the star
destroyers fire on the Falcon, Han could  use  exotic  matter  to  create  a
space-time bulge, so that the laser beams would simply  bend  away.  If  you
consider, however, that the mass of the sun bends passing light rays by only
a tiny fraction of a degree, the energy  necessary  to  bend  a  laser  beam
enough to make it miss the ship would again be  huge-perhaps  equivalent  to
one hundred thousand times the mass of the sun.



     THE MUSIC OF THE SPHERES


     A  third  possible  method  of  faster-than-light  travel  arises  from
superstring theory. Before you read further, I must caution you. Superstring
theory requires that you adopt a whole new view of the universe.  This  view
is consistent with everything we've discussed so far, but  it  reveals  that
underlying the visible world, at the smallest level, is a reality completely
unlike what we've believed. If you thought particles popping out of  nothing
and traveling without moving were hard to believe, have I got a  whopper  to
sell you. Superstring theory attempts to tie  together  all  the  forces  we
observe in the universe in a grand unified Theory of Everything. To do this,
physicists found that they had to adopt a new image of subatomic  particles.
A particle is not a particle at all, they concluded . Instead, a particle is
a resonance created by a tiny vibrating string, rather like a  musical  note
created by a plucked guitar string.

     These resonances appear to us as particles because the strings are very
tiny: a billionth  of  a  trillionth  of  a  trillionth  of  an  inch  long.
Superstring theorists believe that if we could  see  down  to  that  quantum
level-which we can't-we would find not a particle  but  one  of  these  tiny
strings. Strings with different resonances or frequencies are equivalent  to
different subatomic particles, such as the quark, electron, and neutrino. As
these particles interact, their frequencies can form  harmonies,  and  those
harmonies create the physical forces we observe ,  dictating  how  particles
interact.

     The Greek  mathematician  Pythagoras  believed  that  celestial  bodies
created music as they moved, perfect harmonies that he called the  music  of
the spheres. Now, twenty-six centuries later, he may be  proven  right.  Why
should a particle be anything like a musical note? A musical note is a sound
wave made up of energy, defined by a  particular  frequency.  Remember  that
scientists consider matter to be confined or condensed energy. Thus  viewing
matter as an energetic vibration confined to the location of a string  makes
sense. In addition to view of the universe. view of the universe.

     As they studied how the strings would behave, they found that the  tiny
strings could not move in just four dimensions. Although we  appear  limited
to a four-dimensional space-time, the universe must  actually  have  ten  or
more dimensions. And we have a hard enough time visualizing four!

     These additional dimensions actually make it much easier for scientists
to explain how all the different forces we observe  are  actually  different
manifestations of a single, unified force. How  do  extra  dimensions  help?
Imagine, for example, that you are lost on the planet of Tatooine . You walk
and walk across the desert but are unable to find civilization. Finally  you
come to a rocky outcropping and you climb it. From the top you can see for a
great distance, and the geography of the terrain is  apparent.  You  realize
that you have been crossing a dry lake bed, and you see at  the  far  end  a
road that leads toward Mos Eisley. While you were  on  the  ground,  working
virtually in two dimensions, the geography was difficult to understand . Yet
from the higher perspective  of  the  third  dimension,  the  pattern  below
becomes clear. Similarly, adding dimensions to our picture of  the  universe
adds clarity and reveals previously hidden patterns.

     But how can the universe have ten or more  dimensions,  when  we  don't
experience this many? Imagine that the universe is a giant toilet paper tube
and we live on the outside of it. We inhabitants living on  the  outside  of
the tube can travel in two directions, along  the  length  of  the  tube  or
around the circumference of the tube. Yet what if the diameter of  the  tube
becomes very, very small? Then we inhabitants will believe we are living  in
a one-dimensional universe, like a string, in which we can only travel along
the length. So if one dimension is curled up very tightly, smaller than  our
ability to measure, we might not know it exists. Why would this dimension be
curled up, or compactified, in the first  place?  Scientists  still  haven't
found an answer to that. They theorize that during the Big Bang, six of  the
ten dimensions curled up, while four expanded, as we've described earlier.

     According to theory, these dimensions  are  curled  up  to  the  Planck
length, as Dr. Kaku describes it, "100 billion billion  times  smaller  than
the proton." It is at this quantum level  that  particles  foam  up  out  of
nothing, and our ideas of space and time break down. How could  these  other
dimensions allow Han Solo to travel faster than light? If Han could uncurl a
dimension, he might be able to take a shortcut  through  it.  This  shortcut
would be through higher-dimensional hyperspace, like  a  wormhole.  Once  he
reached his destination, he could theoretically curl the dimension  back  up
again. Like the wormhole, this method could explain  the  Falcon's  jump  to
hyperspace, quick travel, and return to normal space.

     Whether this is possible-and whether  the  universe  actually  has  ten
dimensions-remains uncertain. Marc Millis is skeptical about  "assuming  the
existence of hidden dimensions we can't see and can't interact with."  Since
we don't interact with them, he argues, "They won't be useful even  if  they
do exist." If they do exist, the energy necessary to access such  incredibly
small dimensions is huge. This is the Planck energy, ten  thousand  trillion
trillion electron volts, the  energy,  according  to  Dr.  Kaku,  "at  which
space-time becomes unstable. If we can master the energy found at the Planck
length, we will master all fundamental forces."

     Our most powerful particle accelerator can give a particle an energy of
one trillion electron volts. We need an energy ten quadrillion times greater
than that. Yet  if  we  consider  that,  according  to  Dr.  Kaku's  earlier
estimate, Star Wars's galactic Republic and Empire  have  access  to  energy
more than one hundred thousand quadrillion times greater than  we  do,  they
could access these tiny  dimensions.  They  might  even  consider  traveling
through hyperspace as simple as dusting crops.



     WHICH WAY IS UP?


     In addition to traveling  quickly  across  vast  distances,  Star  Wars
spaceships have another  intriguing  ability.  They  are  able  to  generate
artificial gravitational fields for the comfort of their passengers .  In  A
New Hope, Han Solo alerts Luke that TIE fighters are pursuing them in  their
escape from the Death Star. Han and Luke stride across the deck to a ladder.
Han goes up the ladder, Luke goes down. At each end of the ladder is  a  pod
with a chair and controls for a quad laser cannon.  A  hemispherical  window
bulges out from the hull of the ship, allowing the operator to have  a  wide
field of vision. One of these pods protrudes from the top of the  Millennium
Falcon, with the operator's chair facing upward; the  other  protrudes  from
the bottom, with the operator's chair facing downward. What  is  interesting
here is that the scene starts in  an  area  of  the  ship  where  artificial
gravity has established a clear up and down.

     Han and Luke are not floating around, but are held to the  deck  as  if
it's the surface of the Earth. The ladder seems to  maintain  this  gravity.
But if this gravity existed throughout the ship, we'd expect Han and Luke to
have a hard time getting into their seats in the pods. In the upper pod, Han
would be climbing up into a chair that's reclined at an awkward angle, as if
he's visiting the dentist. In the lower pod, Luke would have  even  a  worse
time, trying to get into a chair that faces downward. When  he  reaches  the
bottom of the ladder, he would find himself hanging helplessly over the pod.
If Luke lets go at the bottom of  the  ladder,  he'll  fall  down  onto  the
hemispherical window.

     He could instead step down onto the chair, but he'll be standing on its
back. To get into it, he has  to  somehow  work  himself  up  into  it  from
underneath, and even if he manages to get into it, only a  tightly  fastened
seat belt will keep him in. Instead of these bizarre  calisthenics,  we  see
Luke step off the ladder, pivot, and get in his seat, as  if  the  chair  is
upright. And it is. Gravity has clearly shifted. By the time  Luke  finishes
his descent on the ladder, the ladder no longer points down, as it did  when
he began his descent. Somewhere along the way, a shift in artificial gravity
has transformed the ladder into a horizontal catwalk .

     You can actually see this if you watch the scene carefully. Luke  backs
off the catwalk into the pod. He is now standing on the  side  wall  of  the
pod, but with the different gravity in this area,  it  feels  as  if  he  is
standing on the "ground." From his point of view, the pod does not  feel  as
if it's pointing down; instead it seems to be pointing out the side  of  the
ship, and the seat is standing upright beside him. This makes it much easier
for Luke to get into his chair and blow himself up some Imperials. With  the
possible exception of the small fighters, all Star Wars ships appear to have
artificial gravity. They are somehow able  to  reproduce  the  gravitational
field of a planet like Earth on a spaceship . And as we saw on  the  Falcon,
different areas of the ship might even have different gravities. While we're
accustomed  to  spaceships  with  gravity  in  the  movies,  in   actuality,
artificial gravity would be very difficult to produce, and  except  for  the
crudest methods, we have little idea of how to go about it.

     The simplest method, and the only one currently within  our  power,  is
acceleration. As we discussed earlier, gravity and  the  inertia  caused  by
acceleration are equivalent. If a spaceship accelerates at 1 g, those inside
will feel an inertial force pressing them  against  the  back  of  the  ship
exactly the same as the gravitational force they would  feel  pressing  them
against the Earth. The back of the ship then becomes the "ground"  to  those
on board. The problem with using acceleration to create gravity is that  you
are forced to maintain your acceleration at 1 g.

     If you needed to speed up or slow down-or heaven  forbid,  navigate  an
asteroid field-your gravity would be shifting all over the place. You'd want
to lay in a  good  supply  of  airsickness  bags.  To  avoid  this  problem,
scientists envision a spaceship shaped like a wheel that rotates as it moves
through space. Since acceleration is caused not  only  by  slowing  down  or
speeding up but by  changing  directions,  an  object  moving  in  a  circle
undergoes a constant acceleration. If we envision the spaceship as a  giant,
rotating , hula hoop-type tube with passengers inside the tube, the rotation
would push them against the outermost part of the tube, which would serve as
their "ground."

     While rotation could produce a steady gravity of 1 g,  the  ship  would
still need to speed up, slow down, or maneuver, as in the first example, and
those accelerations would alter the gravity in the ship, as above. To  avoid
that problem, we need to consider some more theoretical solutions. In  these
quite  speculative  methods,  we  could  potentially  compensate   for   any
acceleration of the ship by altering the strength of our artificial gravity.
The artificial gravity would in effect cancel  out  any  inertial  force  by
creating an equal force in the opposite direction.

     One possible path toward creating artificial gravity would  be  to  use
the zero-point field generated by quantum fluctuations. We discussed earlier
Dr. Puthoff's hypothesis that this zero-point field is the cause of inertia.
Since inertia and gravity are equivalent, you might expect that Dr.  Puthoff
believes the vacuum energy is also the cause of gravity. Indeed, Dr. Puthoff
has theorized that a body's interaction with the  zero-point  field  creates
gravity. While this hypothesis also remains very controversial, if it is so,
and if we could manipulate the zero-point field, then we  could  potentially
create artificial gravity on our spaceships.

     Since we would be manipulating the fundamental cause  of  both  inertia
and gravity, it seems as if we could easily compensate for any  acceleration
of the ship in any direction. And if we're really the masters of gravity, we
could eliminate the gravitational attraction between a planet and our  ship,
making it  much  easier  to  take  off.  Most  scientists,  however,  remain
skeptical about the connection between the zero-point field and both gravity
and ... that the only well-understood method of creating artificial  gravity
on spaceships is to rotate them.

     Other than that, he advocates the old-fashioned method  for  generating
gravity: mass. He suggests "putting megatons of ultradense matter in a  thin
film under the floorboards." Let's see Han Solo make a  quick  getaway  from
the Death Star with that.



     WH1C1H WAY 1S DOWN?


     While we see gravity in Star Wars spaceships, we see antigravity in  an
even wider range of vehicles. Luke  Skywalker's  speeder  on  Tatooine,  the
speeder bikes on the moon of Endor, Jabba's huge sail barge, and the  battle
droids'   crescent-moon-shaped   STAP   all   appear   to    utilize    some
antigravitational field. They seem able to float effortlessly,  resisting  a
planet's gravitational field. To maintain itself at a certain height in  the
atmosphere, a speeder would have to exert a force equal and opposite to  the
gravitational attraction of  the  planet.  To  accelerate  upward  into  the
atmosphere, the speeder would have to exert an even greater force.  Creating
antigravity is basically the same problem as  creating  gravity,  except  in
reverse. And so it could potentially be created using  the  same  techniques
discussed above.

     "If you can distort the geometry of space," Dr. Alcubierre points  out,
"you can create  antigravity."  Developing  a  technology  that  can  easily
manipulate gravitational forces not only  provides  the  ability  to  create
gravity and antigravity, but to travel rapidly across the galaxy.  Once  one
of these problems is solved, they all are. The one difference is that we  do
have a material  at  hand  that  generates  gravity;  in  fact,  all  matter
generates it. But we don't have a  material  easily  at  hand  that  creates
antigravity. Exotic matter , if it can be  found  or  made,  would  be  that
material. Since exotic matter, in theory, has negative energy,  or  negative
mass, and so creates the exact opposite gravitational effect as gravity,  we
could use it to cancel out the weight of the speeder. If we measure the mass
of the speeder, and then put into  the  speeder  an  equal  mass  of  exotic
matter, the mass of the total will be effectively zero.

     Without any mass, the speeder will not be attracted toward  the  planet
or repulsed away from it; the vehicle will tend to stay at  whatever  height
we leave it. Conventional thrusters could then move the vehicle up or  down,
forward or back, and side to side. To counteract the mass of any passengers,
we'd need the speeder to either produce more exotic matter,  or  to  provide
some upward thrust. You might think  that  a  vehicle  able  to  resist  the
gravitational attraction of an entire planet  would  have  to  access  great
energies. But the energy needed to hold your car off the  ground  isn't  all
that great; your tires do it every day. Your mechanic raises your  car  even
higher when he puts it on a lift. And  you  yourself  resist  the  force  of
gravity when you climb stairs, jump in the air, or hang from a tree branch.

     The problem is that, unlike electric or magnetic forces, we  don't  yet
understand how to manipulate gravitational  ones.  And  you'll  get  awfully
tired hanging from that tree branch.



     HAN'S BOAST


     Now that we've explored possible methods  by  which  the  Falcon  might
travel through space, let's see if we can make  sense  of  Han's  incredible
boast, that the Falcon made the Kessel Run in less than 12 parsecs.  If  you
don't know why Han's boast is so incredible, it's because a parsec is a unit
of distance. A parsec equals 3.258 light-years or 19 trillion miles. So when
Han brags that he made the Kessel Run in less than 12 parsecs, he's bragging
that he made the Kessel Run in less than 228 trillion miles. That's kind  of
like saying you ran the 100-yard dash in 100 yards.

     Yeah, so? Many loyal fans, desiring to save Han  Solo  from  stupidity,
have tried to come up  with  explanations  for  this  seemingly  nonsensical
statement. Here are a few I've heard: (a) distortions of time and  space  at
high speeds make a distance measurement just as revealing as  a  measurement
of time (b) Han discovered a shorter hyperspace  route  to  Kessel  (c)  the
Kessel Run is a race requiring different cargoes be delivered  to  different
ships, and the ships are moving away as the race goes on. _  So  making  all
the  deliveries  while  traveling  the  shortest  distance  would  be   very
impressive (d) Han was testing Obi-Won and Luke to  see  how  gullible  they
were, so he'd know how much money to charge these two  hicks  Author  A.  C.
Crispin even worked an explanation into her book The Hutt Gambit,  part  two
of The Han Solo Trilogy.

     Crispin explains that Kessel is next to a cluster of black holes  known
as the Maw. Reaching Kessel in "less than 12 parsecs" would imply  that  Han
had flown dangerously close to the strong gravitational fields of the Maw, a
feat of great daring. It does seem a bit unreasonable, however, for  Han  to
think Luke and Ben would be impressed by this obscure bit of smuggling lore.
Allow me to throw my own two cents into this  attempt  to  rescue  Han  from
stupidity. Let's take a look at explanation (a). As we know, if Han  travels
toward Kessel at just below the  speed  of  light,  the  distance  he  would
measure between himself and Kessel would be  less  than  the  distance  he'd
measure if he was at rest with respect to Kessel. The closer he  travels  to
the speed of light, the more the distance contracts.

     So if Han is traveling so close to the speed of light that the distance
between himself and Kessel appears to be only 12 parsecs, that  could  be  a
very impressive sign of the Falcon's  speed.  Unfortunately,  even  if  he's
traveling at .999999 c, it will take him almost forty years to travel  those
12 parsecs and reach Kessel. So that explanation doesn't work out  so  well.
Most likely, Han is traveling faster  than  light  anyway,  considering  the
distances involved. So perhaps explanation (b) is the correct one.  In  that
case, perhaps Han is using a wormhole to get to  Kessel.  If  he's  able  to
create a wormhole with each end where he wants it, though, he should get  to
Kessel in much less than 12 parsecs. Even if he can't create a wormhole that
ends exactly beside Kessel, say because of black holes or  other  obstacles,
creating one that ends so for away will be pretty inconvenient,  though  not
as bad as our first scenario.

     In this case, 12 parsecs is the uncontracted distance someone  at  rest
with respect to Kessel would measure. So once Han comes out of the wormhole,
he can accelerate  to  .999999  c  and  contract  the  12  parsecs  to  just
one-twentieth of a light-year. At that speed, it will take him only 20  days
to reach Kessel, which is at least better than 40 years.  Yet  the  fans  he
left on Kessel at the beginning of the  race  would  probably  be  dead  and
buried. The some would hold true if Han was warping space. He should  arrive
at his destination while hardly moving at all, and if he needs to move short
distances at each end of the warp to get to his exact destination, they need
to be much shorter than 12 parsecs for him to finish the  run  in  a  timely
manner.

     Explanation (c) sounds like a bizarre game show that  I  wouldn't  mind
watching some time. But I'll have  to  say  the  most  likely  seems  to  be
explanation (d). If Ben and Luke had shown a bit more enthusiasm over  Han's
performance of the Kessel Run, he might have asked  them  to  pay  twice  as
much.



     WHEN IN DOUBT, BLAST!


     Their light beams crisscross the battlefield, whether it's on  the  icy
plains of Hoth or in the black vacuum of space. They can be carried  in  the
hand, mounted on a speeder, or built within a space station the  size  of  a
small moon. They can stun, kill, or destroy a planet. And they  make  really
cool sounds. We see many light-beam weapons in Star Wars. The  Death  Star's
planet-destroying weapon is said in the  Star  Wars  Encyclopedia  to  be  a
super-laser.

     Star destroyers are armed with "turbolasers ." Blasters are  also  said
to fire beams of "intense light energy." Might we someday have laser weapons
similar to those shown in Star Wars? The word laser is an acronym,  standing
for Light Amplification by the Stimulated Emission of Radiation. Let's first
look at the "radiation" part of laser. Light is emitted, or radiated, by  an
object when the atoms and molecules that make up that object release energy.
If that electromagnetic energy happens to be of a wavelength visible to  the
human eye, we see it as light. To understand  how  and  when  atoms  release
energy, we need to consider how an atom  is  put  together,  with  electrons
orbiting a nucleus of protons and  neutrons.  The  electrons  can  orbit  at
different distances from the nucleus, depending  on  how  much  energy  they
have. Let's do a thought experiment.

     Imagine yourself standing in an elevator  on  the  bottom  floor  of  a
skyscraper. For our purposes, let's call this floor zero. You receive a jolt
of energy that sends the elevator up to the first floor. As you stand on the
first floor and the Earth rotates, you are essentially orbiting  the  Earth.
You have a certain potential energy now, reflected by your height in Earth's
gravity.

     If you jump out the window, that potential energy will be converted  to
kinetic energy. But let's say that instead  of  jumping,  you  receive  more
energy, which kicks the elevator  up  another  flight.  You  now  have  more
potential energy than before. Your change in energy is exactly equal to  the
amount of energy the elevator received.  This  is  similar  to  the  way  an
electron functions within an atom. When the atom  absorbs  energy,  as  when
photons of light fall upon it, the electrons are sent up into higher orbits.
Later the electrons spontaneously drop to  lower  orbits  and  release  this
energy.

     Each particular drop-say from the third floor to the second  floor,  or
from the second floor to the first floor-releases a photon  with  an  energy
equal to the change in of the photon it emits.  It  might  be  a  wavelength
within our visible spectrum, or it might be  one  outside  of  it,  such  as
infrared, ultraviolet , or X-ray radiation. Such  spontaneous  emission,  as
it's called, is  what  causes  light  to  be  emitted  from  the  sun,  from
incandescent light bulbs, and from fluorescent  lights.  While  these  drops
occur spontaneously, we can also stimulate atoms to release their energy  at
a certain time. That's what the "stimulated emission" part of  laser  means.
Say we have an atom with an electron in an excited state-on the second floor
of the skyscraper.

     Now we radiate that atom with a bunch of photons of  the  exact  energy
that our electron would release by going down to the first floor. If  you're
the electron, it's sort of like hearing the  screams  of  a  bunch  of  your
friends jumping from the second floor to the first floor. It sounds so  fun,
you want to jump too! The photons can actually stimulate an electron to drop
down a floor. If we have a bunch of such  atoms,  this  can  cause  a  chain
reaction , with many electrons throwing caution to the winds,  jumping,  and
releasing photons of equal wavelength.

     One way to make the most of this chain reaction is to  send  the  newly
released photons back through the atoms again, so they  will  stimulate  the
emission of yet more photons. Scientists  do  this  by  placing  mirrors  on
either side of the atoms, so the light is reflected back and  forth  through
them, the cries of jumping electrons echoing  back  and  forth,  stimulating
more and more emission. While one of the mirrors is  completely  reflective,
the other reflects only part of the  light  and  transmits  the  other  part
through it. This transmitted portion is what we see as the laser beam.  With
this technique, we can stimulate the light to be released when we  want  it.
Even better, the light will be of one uniform wavelength and in phase.

     This means that the peaks and the troughs of  all  the  waves  will  be
lined up with each other, so instead of  interfering  with  each  other  and
canceling each other out, they will add to  each  other,  making  the  peaks
higher and the troughs lower. This is where the "light  amplification"  part
of laser comes in. While a laser is basically just light, it is  light  that
can be focused onto a precise spot and can have high, extremely concentrated
power. Lasers can produce a steady  beam  for  long  periods,  or  they  can
produce a very intense beam in short pulses. Such pulses can occur thousands
or millions of times per second. The ability to focus  on  a  tiny,  precise
spot is what allows us  to  put  huge  amounts  of  information-640  million
bytes-onto a CDROM , which can then be read  by  a  laser.  It  also  allows
lasers to perform delicate microsurgery,  vaporizing  specific  cells  while
leaving others undamaged. Lecturers use pen-sized laser  pointers  and  guns
use laser sights because of their ability to  remain  tightly  focused  over
distances.

     The coherence and single wavelength of laser light make it  useful  for
conveying information, as it does when it  reads  the  bar  codes  off  your
cereal boxes at the grocery store or carries your long-distance phone calls.
Lasers print out our documents, remove tattoos, and shatter  kidney  stones.
The amplified light of lasers can also be  very  powerful,  particularly  in
intense pulses. The highest-powered lasers,  emitting  trillions  of  watts,
give off a pulse only a billionth of a second long. A series of  pulses  can
drill through hard materials like titanium or diamond. To have an effect  on
the material it strikes, though, the laser light must  be  absorbed  by  the
material. If it is simply transmitted  through  the  object,  it  will  have
little effect.

     If it's reflected by the object, then the  shooter  is  in  for  a  big
surprise just like Han Solo in the garbage masher. This means the laser must
be designed to emit light of a wavelength  that  will  be  absorbed  by  the
particular material one wants to target. As the target absorbs this  intense
light energy, it will begin to heat, melt, and then vaporize.  The  military
has already developed lasers for a number of applications  .  A  low-powered
laser can blind enemy sensors or even blind a person. A higher-powered laser
could set a person's  clothes  on  fire  or  burn  him,  like  a  long-range
flamethrower. A megawatt laser can burn a hole through a jet up to six miles
away-though it needs to maintain contact with the aircraft for  one  to  two
seconds.

     Two of our most powerful  lasers  can  each  generate  beams  with  2.2
megawatts of energy. Alpha is being developed as a space- based laser.  From
Earth orbit, it would destroy enemy missiles thousands of miles away,  using
an infrared laser beam with an energy intensity at its  core  several  times
that of the sun's surface. Our other 2.2-megawatt laser, MIRACL, is  testing
the ability of ground-based lasers to target objects in space. During a test
last year, MIRACL was able  to  hit  a  satellite  in  Earth  orbit.  MIRACL
purposely did not destroy the satellite, since the test was designed  merely
to show that the laser could target and hit the satellite.

     But researchers say the laser could just as easily have melted it. Thus
it seems the lasers we have today would be capable  of  doing  many  of  the
things we see in Star Wars. We could injure or kill people;  we  could  burn
structures or melt holes in  walls;  we  could  destroy  targeted  areas  of
spaceships, assuming we could keep a beam on them for long enough. The  main
difference between Star Wars lasers and ours is the size.  Both  MIRACL  and
Alpha are huge; the two of them together  would  probably  fill  the  entire
Millennium Falcon. Even a less ambitious laser, one that  could  potentially
burn a hole through a speeder bike or kill a person,  as  blasters  can  do,
would be the size of a truck. That would be kind  of  hard  to  fit  into  a
holster.

     This size problem arises from several factors. One is heat. Lasers have
only 1 to 30 percent efficiency, which means that only this  much  of  their
energy emerges in the final beam. Most of the rest of the energy, up  to  99
percent, is lost as heat. In a very powerful laser,  this  heat  can  become
very intense, shattering the laser's  mirrors.  Elaborate  cooling  systems,
involving fans or liquid coolants, must be devised.  These  are  often  both
large and heavy. Another factor keeping lasers large is power. While we  can
create lasers that emit extremely powerful energies, we need to  pump  great
energies into them to make them work.

     That energy source takes space. While this might not be  a  problem  on
the Death Star or a star destroyer, it would  be  on  the  Falcon  or  in  a
blaster. The most compact high-power generator we currently have  for  laser
weapons is thirty-five feet long, eight feet wide, and eight feet tall.  The
military is very excited that they can fit  the  fifteen-megawatt  generator
into a tractor trailer. "You can put the energy of a nuclear power plant  on
a light beam," Dr. Kaku says, "but that means you have to carry that nuclear
power plant with you. There is no portable power pack, other than a hydrogen
bomb." That doesn't sound very healthy, and I still don't think you can  fit
one in a holster. Yet Dr. Kaku admits that "Maybe a  Type  III  civilization
has mastered that power. In one hundred years time, we  will  probably  have
some form of nanotechnology, the ability to make machines the size of atoms.
In which case, rayguns are not such a farfetched idea."

     If we can solve the cooling problem  and  the  power  problem,  perhaps
blasters can be in our future. They won't quite be like what we see in  Star
Wars, though. In the movies, we see a lot of beams  shooting  through  space
from one ship to another. A laser beam in  space  would  be  invisible.  You
would only see it if you were looking at the enemy gun the moment  it  fired
or if you were looking at the target as it hit. It would look like a  circle
of light on the target. The actual beam of a laser only becomes  visible  if
it passes through a lot of dust. The dust scatters some of the light out  in
different directions, allowing you to stand off to  the  side  and  see  the
beam.

     In the movies we also see lasers knocking space ships back  as  they're
hit. I remember feeling the Falcon's Pain in The Empire Strikes Back as it's
struck by a star destroyer's laser and recoils from the impact.  Yet  lasers
do not carry enough momentum to send their targets reeling. Their energy  is
in the form of intense heat. We also need to be aware that lasers are  often
not as effective within an atmosphere. Fog, rain, or smoke, like  dust,  can
scatter and weaken the beam. We could imagine a scene on Naboo  where  enemy
forces are in a pitched blaster battle with Qui-Gon and Obi- Wan.  The  rain
starts to pour down, and suddenly no one's blasters are effective.

     Using very powerful lasers within an atmosphere can cause problems. The
air absorbs a tiny fraction of the laser light passing through  it.  If  the
beam is extremely powerful, like that of a Walker, that  tiny  fraction  can
significantly heat the  surrounding  air,  creating  turbulence.  Turbulence
forms areas of higher and lower air pressure, and as the laser  beam  passes
through these areas, it can bend slightly. So a Walker might aim at an Ewok,
but end up hitting another Walker instead. The Empire might  want  to  think
twice before using those heavy lasers  within  a  planet's  atmosphere.  The
effect of a laser on the surrounding air is actually used as an advantage in
a recently designed laser. This laser can stun, just as  the  stormtrooper's
weapon near the beginning of A New Hope stuns Leia. The laser emits  a  beam
of high-frequency ultraviolet light.

     The intense beam actually  breaks  apart  the  molecules  in  the  air,
creating a tunnel of positively and  negatively  charged  ions  between  the
laser and the victim. While the laser beam itself does the victim  no  harm,
the weapon immediately sends an electrical current down the ionized  tunnel,
and the current zaps the victim. Depending on the  current's  strength,  the
weapon can cause disabling muscle contractions or induce a heart attack. The
weapon has a range of more than one hundred yards. We're  still  stuck  with
the size problem, though; this one is as big as a table. If  lasers  can  be
gentle enough to stun, can they also be powerful enough to destroy a  planet
as the Death Star's laser does? At least size isn't an issue here, since  we
have a huge space station to play with. Dr. Burns estimates that to vaporize
a planet, we'd need a laser with a billion  trillion  times  the  energy  of
MIRACL. But perhaps we don't need to vaporize it. Dr.  Stuart  Penn,  senior
research fellow at South Bank University in London, suggests another  way  a
laser might destroy a planet. "The laser could vaporize a narrow  tunnel  to
the core of the planet. Then heat the core so it expands and melts. I'm  not
sure the planet  would  actually  explode,  but  the  laser  would  probably
rearrange it."

     The biggest difficulty in generating a beam powerful enough for  either
of these options would be in finding a stable lasing  material-the  material
whose electrons are doing all that jumping. Lasing materials can  be  gases,
crystals, or even semiconductors.  But  in  very  powerful  lasers  ,  these
materials are subjected to extreme heat. At  these  high  levels,  Dr.  Kaku
explains, "the gas overheats, the ruby cracks." Yet he believes that if  the
Empire could overcome this limitation, they could  build  the  Death  Star's
weapon. Dr. Kaku even seems to admire the Death Star a bit. "The Death  Star
is very practical. We could even build it ourselves, if we had enough  gross
national product. We have nuclear weapons that could crack  the  Earth.  You
can imagine what a Type III civilization could do. They could build a  laser
powered by a hydrogen bomb, an X-ray laser. I've got no  problems  with  the
Death Star."

     I have one, actually. When the Death Star fires, six  laser  beams  are
generated around the circumference of a circular depression on the  exterior
of the space station. The six beams meet at the center  of  the  circle  and
head down toward the planet as a single,  huge  beam.  What  would  actually
happen, I'm afraid, is the six beams would pass through each other and  head
off in six different directions, probably all of them missing the planet. If
we're lucky, maybe they'd run into some star  destroyers.  While  the  Death
Star may have been extremely effective in destroying Alderaan, as weapons go
it was a bit crude. Let's consider one that's "an elegant weapon, for a more
civilized age."



     LIGHTNING BOLT ON A STICK


     As prominent a role as the  light  sabers  play  in  Star  Wars,  these
weapons seem to be the one thing scientists have no clue how  to  make.  And
perhaps that's appropriate, since these weapons channel  the  Force  through
them, a mystical energy field that seems to defy every scientific law around
(but  that's  the  next  chapter).  When  I  first  saw  A  New  Hope  as  a
seventeen-year-old, I thought the light sabers were lasers. Yet  lasers,  as
we discussed above, are beams that will continue in a straight  line  unless
they are absorbed, reflected, bent, or  scattered  by  some  substance.  The
light sabers, instead, just stop. Also, the laser beams wouldn't be  visible
unless there was a lot of dust in the air. And two laser  beams  would  pass
right through each other, rather like two flashlight beams.

     A much better candidate to create a light saber is plasma. A plasma  is
a gas that's been heated to extremely high temperatures. Let's  go  back  to
our electrons in elevators. As a gas is heated, the atoms of gas move faster
and faster, gaining energy. The electrons get more and more shots of energy,
moving up higher and higher in their skyscrapers until  they  at  last  blow
right out through the roof. Such an electron no  longer  orbits  its  atom's
nucleus but is free and independent.

     Before, the atom, with its negatively charged electrons and  positively
charged nucleus, was electrically neutral. Now, although the net  charge  of
the plasma remains zero, the negatively and  positively  charged  particles,
called ions, are free to move and act separately. Since electrically charged
particles generate electric and magnetic fields,  a  plasma  will  act  much
differently than a regular gas. In fact, a plasma acts so  differently  that
some scientists consider it a fourth state  of  matter,  in  addition  to  a
solid, liquid, and gas.

     Through their electromagnetic forces, the ions can affect each  other's
behavior from large distances, so that movement  at  one  end  often  causes
movement at the other. Dr. David Bohm, a prot ege of Einstein's who  studied
plasmas extensively, concluded that plasmas  do  not  behave  as  individual
particles but as a collective, organized whole. In fact, he  often  had  the
impression that plasmas acted as if they were alive.  This  makes  a  plasma
seem all the more appropriate as the main constituent of  the  light  saber.
Yet as bizarre as plasmas are, they are all around us.

     All stars are made of plasma, including our sun. The outer layer of our
atmosphere is a plasma. Plasma can be found in lightning bolts, and  we  use
plasma in the tubes of fluorescent lights. Since  the  sun,  lightning,  and
fluorescent lights all emit light, it's not hard to imagine that a  beam  of
plasma could produce the glow of a light saber. Light is emitted by a plasma
when an electron decides to recombine with a  nucleus,  dropping  back  down
through the hole in the roof of  the  skyscraper  and  letting  out  a  long
scream. In most plasmas, the processes of electrons being freed from  nuclei
and recombining with nuclei are  occurring  constantly.  Fluorescent  lights
stimulate these processes to create a glow discharge  by  placing  a  plasma
between two electrodes.

     The color of the glow depends on the composition and temperature of the
plasma. In Chapter 1, we discussed the activity of similar charged particles
, or ions, in space within the Van Allen Radiation Belts.  Earth's  magnetic
field traps ions and causes them to spiral around the magnetic field  lines.
These magnetic field lines draw closer and closer together near the  Earth's
poles, where they converge. Since a particle cannot cross a  magnetic  field
line, it must stop, turn around, and  spiral  back  the  way  it  came.  The
magnetic pole thus serves as a "magnetic mirror."

     With a magnetic mirror at each pole, the particles are trapped within a
certain region, forced  to  bounce  back  and  forth  between  the  mirrors.
Similarly, physicists use magnetic fields, magnetic  mirrors,  and  electric
fields to contain plasmas within a  particular  region.  These  fields  must
exert an inward pressure equal to the outward pressure of the  plasma.  They
can hold a plasma in a cylindrical shape, and  they  can  even  control  the
width of the cylinder by manipulating the strength of the fields.  We  could
thus imagine a long thin cylinder, rather like a light saber,  made  out  of
plasma. Yet we have three major problems.

     First, as with the laser, we lack a method for creating a clear  cutoff
for the length of the cylinder. Plasma  cylinders  are  of  limited  length,
since scientists can produce only so much plasma, and they can  set  up  the
necessary magnetic fields only within a limited region  .  Yet  we  have  no
method for "capping" the end of a cylinder as seems to be the case with  the
light saber. Plasma simply leaks out the ends of  the  cylinder,  where  the
fields fail to trap it.  Since  the  plasma  of  a  light  saber  must  have
extremely high energy to cut through metal and skin, it would leak out  very
quickly. Marc Millis admits, "Light sabers really twist my brain  over,  how
they terminate at a certain distance." Even if we theorize  that  the  light
saber's handle continually pumps out more plasma  into  the  cylinder  ,  we
should see a diffuse glow at each end  as  material  jets  out.  To  prevent
leakage-which would quickly vaporize the skin off  Luke's  hand-we  need  to
create a cylinder that has no ends.

     Scientists do this by curling the cylinder around in a circle, creating
a donut-shaped torus. Millis imagines a light saber of this shape  would  be
more possible. "You could have a torus of hot plasma, a donut shape. A stick
would go through the hole of the donut and hold the  donut.  It  would  work
kind of like a mace." We'll have to wait for the next movie  for  that  one.
Dr. John Schilling, research engineer at SPARTA, Inc., has another idea  for
a shape that closes in on itself. He  imagines  a  configuration  where  the
magnetic and electric fields force the plasma to travel up in a very  narrow
stream in the center of the light saber and come back down along the outside
of the  saber,  creating  a  tall,  skinny  plasma  "fountain."  This  could
potentially look like the light saber we  see  in  the  movies  .  "Actually
implementing such a system," Dr. Schilling says, "especially to  the  extent
of getting the nice, neat cutoff at the tip, would be extremely  tough,  but
not outside the realm of possibility ."

     Our second problem is familiar from our  discussion  of  the  blasters:
space. The plasma and all its confining fields are  generated  from  a  tiny
cylinder about the size of a flashlight. In that space we need a very strong
power supply, a cooling system, and  plasma  sources.  If  we  could  create
something like a light saber today, all the required systems  would  fill  a
building. "The light sabers command a lot of energy in  a  small  amount  of
space," Millis says. "It has the energy to vaporize a hand off, and  in  the
space of two D-cell batteries. Imagine the Energizer bunny on those."

     Third, even if  we  could  generate  plasma  and  an  extremely  strong
magnetic field from the light saber handle, the  strength  of  the  magnetic
field would decrease quickly as the plasma moves away from  the  handle.  So
our leakage problem would become even  worse.  Placing  the  handle  in  the
middle with a shorter plasma beam coming out each end of  the  handle  would
offer some help with this problem. Yet the two blades on Darth Maul's  saber
are each as long as a single-bladed saber,  so  he  would  suffer  the  same
problem twice over. If we could solve those problems, a  plasma  beam  could
potentially behave as the light sabers  do.  The  confining  electromagnetic
fields of each beam could repel each other, preventing one beam from cutting
through another. But the beams could in theory cut through metal, bone,  and
other obstacles. Dr. Burns estimates that such a plasma would have to be ten
million times more dense than any we've created on Earth, and be  ten  times
hotter, around 200 million degrees. The huge energy density  of  the  plasma
would allow it to vaporize its way through just about anything  it  touches.
Unfortunately, heat from the beam would also  radiate  out  to  things  that
don't touch it. This heat would be less intense than the heat from  actually
touching the beam, just as sitting in the sun heats you less intensely  than
touching the sun.

     Yet the plasma is so hot that it would burn  anything  close  by,  like
Luke's hands, arms, and face. Dr. Schilling says that anything  sufficiently
close to the saber "would get an industrial-strength case of sunburn. At the
least the saber would be painfully hot, and maybe enough  to  severely  burn
nearby objects." In that case, perhaps Luke would prefer to mail  the  saber
to Vader and activate it by remote control. While  light  sabers,  blasters,
and everyday trips through hyperspace remain far-off dreams, scientists  are
beginning to see ways in which these dreams might someday become reality.

     "There are possibilities," Dr. Alcubierre says. "And I would love to be
able to visit other stars." Theoretically, rapid space travel  is  possible.
The trick is in translating theory into reality. We face a harder  challenge
with the  topic  for  our  final  chapter.  A  theory  that  allows  you  to
communicate telepathically with other people, move objects with  your  mind,
see events at great distances or even into the future, will not be found  in
any standard science textbook.

     Yet the Force raises questions about the nature of  our  universe  that
science has been struggling to answer for as long as  science  has  existed.
And perhaps, in searching for some  answers,  we  can  shed  light  on  this
mystical power that underlies all the Star Wars films.

     The Force

     Kid, I've flown from one side of this galaxy to the other. I've seen  a
lot of strange stuff. But I've  never  seen  anything  to  make  me  believe
there's one all-powerful force controlling everything. There's no mysterious
energy field controls my destiny. -Han Solo, A New Hope

     It is in every rock, every tree. It is in the air around you, the  book
before you, the planet beneath you. Your body is not a separate object,  but
part of an interconnected universal whole. Everything is a part of you,  and
you are a  part  of  everything.  It  is  always  there,  like  a  sound  so
omnipresent you lose awareness of it. Yet at times, when you are  at  peace,
you can sense the surge of its energy through  you.  You  follow  the  flow,
opening yourself to feelings and information far beyond what your  body  can
tell you. You even, at times, control it, directing its energy  toward  your
own ends. It  can  levitate  objects.  It  can  transmit  thoughts.  It  can
influence the weak-minded. It can reveal visions of the past and the future.
It bestows on those in tune with it a sixth sense and life after  death.  It
has a dark side and a light side.

     It is the Force, the  heart  and  soul  of  George  Lucas's  Star  Wars
universe. It is also the most fantastical and least scientific  ...  from  a
mixture of myth, magic, and religion. So shouldn't  science  just  keep  its
nose out? Yet the very purpose of science is to understand what has not  yet
been understood.  Throughout  its  history,  science  has  been  faced  with
inexplicable phenomena and invisible forces. As our  understanding  of  them
grows greater, the questions we face likewise grow greater.

     And in its quest to understand  the  great  mysteries  -as  cosmologist
Stephen Hawking says, "why it is that we and the universe exist"-science and
mysticism often connect and sometimes overlap. It is  in  these  areas  that
science might offer us some insight into the Force, and into  that  ultimate
question: Could the Force really exist?



     MAY THE FORCE BE WITH YOU?


     We can approach this question in two different ways, and these two ways
actually reflect two different  ways  scientists  have  of  looking  at  the
universe. In the first way, we must envision the universe as a collection of
elementary particles and packets of energy that interact with each other. In
this model, all "forces" are simply the effects we observe when  packets  of
energy, called quanta,  are  exchanged  between  particles.  Electromagnetic
forces, for example, are caused by the exchange of photons. In  this  model,
gravity is not caused by the warping of space as we discussed in Chapter  4,
but by  the  exchange  of  tiny  packets  of  gravitational  energy,  called
gravitons, which attract matter to other matter.

     In this view of the universe, if the Force  exists,  then  it  must  be
carried by some particle or quantum of energy. If Luke  is  to  draw  energy
from a tree and  use  that  energy  to  levitate  Artoo,  then  one  of  two
possibilities must occur. First, particles carrying that energy could travel
from the tree to Luke to Artoo. This is not as strange  as  it  might  seem.
Such transfers happen all the time, as when photons of light energy from the
sun travel to your face, heating it.

     Second, a sea of particles could remain stationary, yet allow a wave of
some Artoo, as a wave in the ocean passes through the water. Yet since  none
of the particles we know of behave as the  Force  behaves,  these  particles
must be unlike any we've seen. And to  connect  all  things,  they  must  be
everywhere.



     COULD A SCIENTIST BE A JEDI?


     When Yoda levitates Luke's X-wing out of the Dagobah  swamps,  Luke  is
dumbfounded. "I-I don't believe it."

     "That," Yoda says, "is why you fail."

     If belief is a requirement for a Jedi, could a scientist be a Jedi?  Do
scientists believe the Force could be real?

     Steve Grand, Chief Technology Officer of  Cyberlife  Technology:  "It's
about time the physicists were given something really  awkward  to  mess  up
their nice reductionist theories! Who knows what  kinds  of  real,  emergent
phenomena get conjured up by the frenzied imaginations of a complex universe
?"

     Dr. Ray Hyman, professor emeritus of psychology at  the  University  of
Oregon: "A force  that  really  covers  everything  obviously  unfortunately
doesn't explain anything. It's useless. It's the defining  criteria  of  New
Age thinking: everything is connected to everything else. If it is, so what?
That doesn't explain a thing. One of the problems  of  being  a  skeptic  is
we're seen as party poopers. People who talk  about  the  Force  are  people
looking for fun, adventure. I'd like to believe there's more romance in real
science."

     Dr. Hal Puthoff, Director of the  Institute  for  Advanced  Studies  at
Austin: "If you eliminate precognition, you could almost think of explaining
the other properties of the Force with physics as we know it."

     Dr. Victor Stenger, professor of physics at the University  of  Hawaii:
"What they're talking about here is definitely a quantum notion.  Especially
when you bring consciousness into it and control things with your mind.  The
really difficult thing to explain is the  holistic  nature  of  it.  It's  a
continuous  field  throughout  the  universe   that   acts   instantaneously
throughout the universe."

     Dr. Matt Visser, research associate professor at Washington  University
in St. Louis: "The Force makes neither good philosophy nor good religion. My
biggest difficulty is I see zero experimental evidence  that  anything  like
this exists in reality."

     Dr.  Jessica  Utts,  professor  of  statistics  at  the  University  of
California at Davis: "It sounds like an alternative explanation for the data
we've seen. And it's certainly not one that I would rule out."

     Dr. Michio Kaku, Henry Semat professor of theoretical  physics  at  the
City University of New York: "From a Type 0  perspective,  it's  impossible,
it's silly, it violates everything we know about physics. It's hocus  pocus,
mumbo jumbo New Age nonsense. But what if we look at  it  from  a  Type  III
perspective? That's a technology 100,000 years old. Our technology  is  only
300 years old. As science progresses , it becomes more like magic, as Arthur
C. Clarke observed. At Type III, now we're beginning to enter the  realm  of
magic that is actually physics. What could  I  do  if  I  had  a  technology
100,000 years more advanced? Perhaps all those things."

     Marc Millis, leader of the breakthrough propulsion physics  program  at
NASA: "It begs not to be explained.  Once  it's  explained,  its  magic  and
mystical allure go away."



     THE FIFTH ELEMENT


     While the Force combines a unique blend of characteristics, the idea of
some unique element that fills all space and so connects all things has been
around since  ancient  Greece.  The  Greeks  believed  that  all  space  and
everything in it was permeated by an invisible material  called  the  ether.
The ether was the substance of the heavens . Aristotle called the ether  the
quintessence or fifth essence, after earth, air, fire, and water. The  ether
was said to connect us to each other and to the rest of the universe. As the
planets moved through the ether, they sent ripples through it that  affected
people on Earth. This was how the Greeks  explained  astrology,  the  belief
that the positions of the stars and planets influence events  on  Earth.  As
science became more sophisticated in the 1800s, our view of the ether became
more specific. It had to be massless, since it had not been detected.

     Yet scientists still believed the ether must exist. Just as ocean waves
are propagated through water and sound waves  are  propagated  through  air,
scientists believed light waves, such as those from  the  stars,  must  also
travel through a medium, the ether. Newton  even  proposed  that  the  brain
might excite vibrations in the ether, giving humans psychic powers. Then  in
1887, scientists A. A. Michelson and Edward Morley did  an  experiment  that
proved  the  ether  did  not  exist.  We  came  to   understand   that   the
electromagnetic radiation that comprises light can  propagate  itself  in  a
vacuum and needs no medium. Although no ether exists as the ancients thought
of it, could some medium of particles transmit  an  as-yet-undetected  force
throughout the universe?

     One possible candidate for the job is the field  of  virtual  particles
continually popping in and out of existence on  the  quantum  level.  As  we
discussed in Chapter 4,  the  vacuum  of  space  is  actually  foaming  with
activity. We discussed then the concept of tapping  this  vacuum  energy  to
power a spaceship . While we have only the roughest  ideas  about  how  this
energy might be accessed, let's bypass that problem and consider whether the
virtual particles in the vacuum might be able to provide  sufficient  energy
for a Jedi to perform feats to amaze and astound his friends.

     Could the zero-point energy potentially be tapped to  levitate  objects
such as Artoo? Let's say Artoo weighs about 220 pounds,  or  100  kilograms,
and let's assume that the gravity of Dagobah is the same as that  of  Earth.
Then to lift Artoo one yard off the ground will require an energy  of  about
ten billion ergs. This actually isn't as much as it sounds.  After  all,  if
Artoo truly weighs only 220 pounds, Chewie can easily lift him a  yard.  The
question is, could the zero-point field provide the energy instead?  If  you
recall our discussion in Chapter 4, estimates of the magnitude of the vacuum
energy differ widely, ranging from so tiny as to be worthless as  an  energy
source, to 118 orders of  magnitude  -a  one  followed  by  118  zeros-times
greater than the energy embodied in all the mass in the universe.

     If the latter were true, it would certainly fulfill Darth Vader's claim
that the power of the Death Star is insignificant compared to the  power  of
the Force. Recent research, however, may have given us our best estimate yet
of the magnitude of this energy. If you  recall,  cosmologists  believe  the
zero-point energy must be small, because as energy, it should have an effect
like mass, most likely creating a gravitational attraction that  would  make
the universe collapse inward. And if for some bizarre reason it instead  had
an antigravitational repulsion , a high zero-point  energy  would  blow  the
universe apart. Scientists had measured  that  our  universe  was  expanding
moderately , and that the expansion was gradually slowing.

     This made perfect  sense  without  having  to  include  the  zero-point
energy. The Big Bang initiated the expansion of space by imparting it with a
huge amount of energy and  propelling  it  outward.  Yet  the  gravitational
attraction of all the material in the universe provides a braking action  on
expansion. Since the measured expansion of the universe could  be  accounted
for in this way, cosmologists concluded that the zero-point energy  must  be
so small that it plays little to no role in the development of the universe.
Yet in a very  exciting  experiment  last  year,  two  different  groups  of
researchers measured the rate of expansion of our universe  is  not  slowing
down, as has long been believed, but is actually speeding up. In fact,  they
estimate it's now expanding 15 percent faster  than  it  did  seven  billion
years ago, when the universe was only half  as  old.  This  is  a  seemingly
inexplicable result.

     Why would galaxies, which should be gravitationally drawn  toward  each
other, be racing away from each other faster and faster? Why is space itself
expanding  ever  more  rapidly?  If  the  expansion  of  space   is   indeed
accelerating, then some repulsive force must be operating that  is  stronger
than gravity. The vacuum energy could potentially provide that repulsive, or
antigravitational, force. Scientists used the newly measured acceleration to
calculate how great the  repulsive  force  would  have  to  be.  While  they
couldn't calculate the absolute value of this zero-point energy, they  could
calculate the ratio of how big it  is  in  comparison  to  the  mass  energy
density in the universe.

     This ratio is relatively  easy  to  calculate  since  it  compares  the
strength of the antigravitational  force  to  the  gravitational  one.  What
scientists found is that rather than being so small as to  be  insignificant
or so great as to be universe shattering, the zero-point energy density  now
appears to be a little over twice as large as the mass energy density of the
universe. What exactly does this  mean  to  Luke  Skywalker,  who  wants  to
levitate his droid? Well, if we can calculate the mass  energy  density,  we
will know the zero-point value is twice this.

     Dr. Michael  Burns,  a  theoretical  astrophysicist  and  president  of
Science, Math, & Engineering, Inc., provides an estimate of the mass  energy
density of the universe. By estimating the average energy  of  a  star,  the
number of stars per galaxy, and the number of galaxies in our  universe,  he
arrives at a very rough estimate of the total amount of mass energy  in  the
universe.

     Dividing this by the estimated volume of  the  universe  gives  a  mass
energy density of one-hundred-millionth of an erg per cubic centimeter. In a
volume of  space  one  meter  on  a  side,  the  zero-point  field  provides
approximately .01 erg. This means that to get the ten billion ergs necessary
to lift Artoo, Luke would need to draw the zero-point energy from  a  volume
of one trillion meters cubed, equivalent to a sphere with a  radius  of  six
miles. This is quite a large area to accomplish a relatively minor task, and
you can imagine how much larger an area Luke would need to draw energy  from
to raise his X-wing from the swamp. Although Yoda claims the task is no more
difficult than raising Artoo, Luke is unable to do it.

     Even though it may be necessary to  access  the  energy  from  a  large
volume to amass a significant amount, Dr.  Kaku  believes  that  the  vacuum
energy is the "one thing in physics that comes close to the Force. The  only
energy that can pervade everything is the zero-  point  energy."  Yet  let's
return to that pesky question we bypassed earlier.  How  could  Luke  access
such energy? It's hard to imagine how a  human  might  use  it  without  any
machinery to assist. Particles holding energy of various kinds zip by us all
the time, yet we're extremely limited in the  ways  we  can  tap  into  this
energy. For example, I can inhale oxygen and use it to burn food to fuel  my
body.

     I can step into a beam of light and absorb heat from it.  But  I  can't
send that heat energy over to my iguana to keep him warm simply by  thinking
about it. Dr. Hal Puthoff, Director of the Institute for Advanced Studies at
Austin, compares the process to a cartoon with one panel  blank  except  for
the words, "And then a miracle occurred." Yet since the technology  in  Star
Wars is so advanced, they may very well  have  come  up  with  a  method  of
accessing the Force that seems incredible to us today. As Arthur  C.  Clarke
said,  "Any  sufficiently  advanced  technology  is  indistinguishable  from
magic."

     The power of the Force certainly seems magical. Dr. Kaku agrees.  "Give
me 100,000 years, 10 billion times 10 billion times the energy of the Earth,
and  then  let's  talk.  If  you  are  in  a  Type  III  civilization,  then
manipulating this force may be possible."



     ARE YOU ONLINE WITH THE FORCE?


     While we can say that an advanced technology may have  some  method  of
manipulating its surroundings with the mind, do we have any  idea  how  they
might do this? Dr. Kaku  stresses  that  "True  telekinesis  I  don't  think
exists; it would violate the four forces of physics," but he  proposes  that
technology might provide an enhancement to biological systems. He cites  the
case of a paralyzed stroke patient who received a brain implant a few months
ago. The implant amplifies his brain signals, which are picked up by a  coil
placed on his head and transmitted to a computer.

     Dr. Kaku calls it "radio- enhanced telepathy." The computer can't  read
his thoughts-we're a long way from that-but with training, the  patient  has
learned what thoughts trigger the computer  cursor  to  move.  He  has  thus
learned how to move the cursor to particular icons, and so  can  communicate
with others. He might point the cursor to a "Hello" icon,  a  "Nice  talking
with you" icon, or an "I'm hungry" icon. In the next stage  of  development,
scientists will hook up the computer so that  the  patient  can  direct  the
cursor to an icon to turn off the lights or turn the channel on the TV.  Dr.
Kaku concludes, "Even on Earth within one hundred years, you can easily  see
the day that by thinking you'll be able to  move  objects  via  radio.  Your
thoughts will be converted into radio signals, sent to a computer,  and  the
computer will carry out your wishes. I can foresee  a  time,  given  100,000
years, when we think and control computers all around us."

     Toward that end, Austrian biomedical  engineer  Gert  Pfurtscheller  is
training a computer to recognize various brain  wave  patterns.  This  is  a
difficult task, because the  brain  is  extremely  complex,  with  over  100
billion neurons , and can  potentially  process  1,000  trillion  pieces  of
information simultaneously, each one  creating  an  electric  signal.  Brain
waves, then, are a complex hodgepodge of  multiple  signals.  Detecting  the
exact  pattern  equivalent  to  "VCR,  play  The  Empire  Strikes  Back"  is
impossible for us at this point. To  simplify  the  task  for  himself,  Dr.
Pfurtscheller  is  specifically  focusing  on  mu  brain  waves,  which  are
associated with  the  intention  to  move,  actual  physical  movements,  or
sensations. Other waves are filtered  out  of  the  signal.  Since  we  have
conscious control over  our  movements,  mu  waves  seem  a  irzmore  likely
contender than other types of waves for human control, and  indeed  subjects
are succeeding at controlling them. Dr. Pfurtscheller has  subjects  perform
movements such as lifting a finger  or  smiling  over  and  over  while  the
computer records the brain-wave patterns associated with preparing  to  make
the movement.

     Once the computer has  distinguished  these  dif-ferent  patterns,  Dr.
Pfurtscheller can connect each one to a different command.  For  example,  a
subject might think about smiling, and the associated mu waves  might  order
the computer to turn off the lights. Thus Luke  could  think  about  lifting
Artoo, and the computer could lift Artoo for him. "When Luke  has  to  learn
how to control this power," Dr. Kaku says, "it's like  learning  to  control
his brain waves. There could be a chip in his clothing  that  picks  up  the
signal."   Similarly,   Dr.   Grant   McMillan   and   colleagues   at   the
Wright-Patterson Alternative Control  Technology  Laboratory  have  built  a
variety of devices that use  the  brain's  electrical  impulses  to  control
lamps, TV sets, video games, and even a flight simulator. So  you  can  turn
the channel or potentially fly a plane-or an X-wing-with your mind.  And  so
you might levitate an X- wing-by ordering it to take off-simply by  thinking
about it.

     Thus  we  might  easily  imagine  humans  in  the  Star  Wars  universe
controlling  machinery  with  their  minds.  Dr.  Charles  Lurio,  aerospace
engineering consultant, even  theorizes  that  this  technology  might  have
originated long ago, and might reproduce naturally  within  the  biology  of
current humans, so they might not even be  aware  of  it.  While  these  are
fascinating possibilities to consider, they don't seem to  reflect  what  we
see in the movies. Luke doesn't fly an  X-wing  with  his  mind.  Star  Wars
technology seems to be of the exclusively  button-punch  variety.  And  many
alien races have the ability to use the Force as well,  making  a  forgotten
bio-implant of some kind unlikely. In addition, the Force  seems  inherently
nontechnological. Luke destroys the first Death Star by foregoing technology
and trusting his feelings.

     And most important, even if Luke's brain waves are being relayed  to  a
computer, that doesn't solve the problem of how the  computer  accesses  the
Force to levitate Artoo. Rather than worrying about how Luke accesses it, we
now have to figure out how the computer might access it. Personally, I  find
it very hard to believe that the Force is with my computer (unless, perhaps,
it's the dark side).

     Perhaps in some way, then,  Luke  can  access  this  vacuum  energy  to
levitate Artoo. But could these virtual particles  be  responsible  for  the
other powers associated with the Force? Let's consider  the  sixth  sense  a
Jedi seems to have. tells Luke that something cold and  evil  lurks  in  the
cave on Dagobah. The Force tells Vader that Obi-Wan has arrived on the Death
Star. To understand how this might work, we need to look at how  the  senses
gather information. A particle can travel from a piece  of  garbage  in  the
Death Star's garbage mashers up through an air vent to the  detention  level
and into Chewbacca's nose,  conveying  information  that  causes  Chewie  to
hesitate diving through the vent.  Similarly,  the  Force  tells  Luke  that
something Luke is sensing something, just Luke is sensing something, just as
Chewie is.

     But how?  As  we  discussed  earlier,  some  particle  must  carry  the
information to Luke, or a wave in a sea  of  particles  must  propagate  the
information. While some unknown ether might be able to do such a thing,  the
virtual particles cannot. They pop in and out of existence too quickly to be
detected. So having a particle travel from the cave to Luke, or from Luke to
Leia when he summons her to rescue him from the  underside  of  Cloud  City,
isn't possible, unfortunately.

     Dr. Stenger points out another problem with having the zero-point field
carry information. "It's just a random fluctuation,  so  it's  incapable  of
producing signals." Are there particles that not only pervade space but live
long enough to carry information from one point  to  another?  Dr.  Lawrence
Krauss, Chairman of the Department of Physics at Case Western University and
author of Beyond Star Trek, suggests another possible  source  of  an  ether
that may carry the Force: dark matter. Dark matter is simply matter that  we
can't see, since it neither radiates nor reflects energy.  Then  how  do  we
know it's there? Astronomers can tell, from measuring the rate  at  which  a
galaxy rotates, that it must be far more massive  than  the  visible  matter
would indicate. If it weren't, its rotation would cause  its  stars  to  fly
apart. Scientists now estimate that visible  matter  comprises  at  most  10
percent of the total mass of the galaxies.

     Each galaxy appears to be set within a large halo  of  dark  matter.  A
galaxy may be about a hundred thousand light-years across; its  dark  matter
halo may be as large as 1.2 million light-years across.

     Dark matter may be simply ordinary material, such  as  extremely  faint
stars, planets, boulders, cold gas, dust, or black holes. Or dark matter may
be made up, not of ordinary material, but of  some  unusual  material  we've
never even observed before. If dark  matter  is  made  up  of  some  unknown
particles, it may be all around us and simply undetectable.  We  could  even
imagine that these particles are emitted by  all  things-every  rock,  every
tree. To consider how such particles might behave, let's look at one type of
subatomic particle that now seems as if it makes up at  least  part  of  the
dark matter in the universe: the neutrino. The neutrino isn't  undetectable,
but  it  has  proven  very  difficult  to  detect.  Although  neutrinos  are
widespread, they interact with other matter so weakly that  they  have  been
compared to ghosts; it took scientists 26 years to find conclusive  evidence
that they exist. And it wasn't until  last  year  that  Japanese  scientists
discovered that neutrinos , which were previously believed to have no  mass,
actually have an infinitesimal  mass  less  than  one-billionth  that  of  a
proton.

     While their mass is tiny, there are so many  neutrinos  throughout  the
universe that they may add up to a significant percentage of the  universe's
mass. Huge quantities of neutrinos were created in the Big Bang;  more  pour
from the sun every day; a hundred trillion of them pass  through  you  every
second. Since they are so tiny and have no electric charge,  they  can  pass
through the Earth without leaving a  trace.  The  problem  with  considering
neutrinos, or dark matter in general , as the medium transmitting the Force,
is that dark matter, by its very definition, is dark.

     We can't see it. We can't see dark matter because it  doesn't  interact
with matter, or interacts only very weakly. And for Luke  Skywalker  to  get
energy or information from dark matter, it must interact with him. Imagine a
Sand Person hits Luke with the blunt end  of  his  gaffi  stick.  The  stick
strikes Luke in the stomach, imparting kinetic energy to  him,  sending  him
stumbling backward.

     The stick gives energy to Luke because it interacts with  him.  If  the
stick flew through Luke as if he weren't even there,  not  interacting  with
him, then it could impart no energy or information to Luke. Neutrinos, which
interact very weakly with normal matter, would fly  through  Luke  Skywalker
without interacting with him at all. Luke is as invisible to  them  as  they
are to him. Could training somehow teach Luke Skywalker how to "make"  these
particles interact with him?

     It's hard to imagine how, though that could offer a potential solution.
Yet some neutrinos carry more energy than intense gamma radiation.  If  such
particles did interact with him as they streamed through him, they'd be more
likely to rip his molecules and cells to shreds than  help  him  levitate  a
droid. So if we want to  find  an  ether  that  can  carry  the  Force,  the
particles need to be around long enough to  transmit  information  from  one
place to another; they need to interact with us in a safe way so that we can
access that information or energy; and they need to be numerous or energetic
enough to make the power to destroy a planet look like peanuts.

     Do we know of any such particles ? No, not yet. There's little doubt in
most scientists' minds that unknown particles exist, yet if  they  did  have
the qualities above, we very likely would have  discovered  them  long  ago.
While the zero-point energy from virtual particles might possibly provide an
explanation for part of the Force, it doesn't fulfill all the  criteria.  In
fact, we can see now what makes the Force so hard to  understand:  the  fact
that it manifests itself in so many different ways.

     But I said earlier that it was possible to approach the  Force  in  two
different ways. Let's move now to scientists' second way of looking  at  the
universe.  Instead  of  a  universe  of  particles  and  packets  of  energy
interacting with each other, this second view describes the  universe  as  a
web of continuous force fields. In this view, gravity is caused  not  by  an
exchange of tiny particles called  gravitons,  but  by  gravitational  force
fields. Similarly, electromagnetic attraction  or  repulsion  is  caused  by
fields. To visualize  the  electrical  field  around  a  negatively  charged
electron, imagine lines radiating out from the electron  in  all  directions
like spokes on a wheel.

     The density or concentration of these lines reflects  the  strength  of
the electrical field. As we move away from  the  electron,  the  density  of
field lines decreases, and the strength of the electrical  force  decreases.
As we approach the electron , the electrical force increases. In  this  view
of the universe, though, the electron  doesn't  even  exist!  Particles  are
simply manifestations of fields, areas with an extremely high  concentration
of field lines.

     Let's see if this model can lead  us  to  further  insights  about  the
Force.



     YOU WILL FINISH THIS BOOK, AND YOU WILL ENJOY IT


     Luke closes his eyes and sees a vision of the future: his friends being
tortured on Cloud City. But how can he see the future, when it  hasn't  even
happened yet? A signal from the future must be  somehow  traveling  back  in
time to Luke. But doesn't that mean the future has already happened, that it
is fixed? Dr. Puthoff believes that of all the strange powers of the  Force,
the most difficult thing to get a grip on  with  physics  is  precognition."
Many scientists resist the idea that time travel might be possible, since it
would violate the principle of causality, the idea that a  cause  must  come
before its effects. Indeed, Luke's vision violates causality.

     If Luke hadn't received the information from the future, he would never
have  left  Dagobah  before  completing  his  training.  The  cause  of  his
leaving-the torture of Han and Leia-actually  occurs  after  the  effect-his
departure. This is like having me drop dead right now at my computer because
someone is going to shoot me in five  years.  It  violates  our  commonsense
understanding of the universe and how it works. Of course, as we've learned,
physics often  violates  our  commonsense  understanding  universe.  On  the
quantum level, the Heisenberg uncertainty principle tells us that  we  can't
measure both the position and the velocity of a particle exactly;  there  is
always a small degree of uncertainty. Thus a particle  could  travel  faster
than light for a short time, and we wouldn't even 111, know. Many scientists
believe that on the quantum level, this does occur.

     On a larger scale, the special  theory  of  relativity  prohibits  time
travel, but the general theory allows its possibility. Since space-time  can
be distorted, a time distortion might be created. One theoretical method  of
time travel is through a wormhole. Since a wormhole connects  two  different
points in space-time, some scientists believe a wormhole might  connect  the
future with the past. We might imagine  a  signal  passing  through  such  a
wormhole, from the future to the present, showing  Luke  his  friends  being
tortured on  Cloud  <  City.  Another  possible  method  involves  tachyons,
theoretical particles that can travel faster than light. As we know from the
special theory of relativity, as the Millennium Falcon  travels  closer  and
closer to the speed of light, its  clock  appears  to  tick  more  and  more
slowly. If it could somehow go faster than the speed of  light,  the  theory
reveals that its clock would actually begin to run backward.

     Thus tachyons, which travel faster than light, appear to move  backward
in time. Let's imagine that after the torture of Han and Leia begins ,  some
tachyons leave Cloud City and head for Dagobah. These  tachyons  effectively
move backward in time, arriving  at  Dagobah  before  the  torture  actually
begins. If the Force allows Luke to somehow access the  information  carried
by the tachyons, he might see the future. Yet time travel presents problems.
If one can see the future, does that mean  the  future  is  preordained  and
cannot be changed? In the case of either wormholes  or  tachyons,  it  would
seem that we are peeking in at something that has "already" occurred and  is
unchangeable.

     Star Wars avoids this conclusion when Yoda explains, "Always in  motion
is the future." What exactly we would see  in  that  case  is  unclear.  One
possible future? Or an event that  occurs  in  all  futures?  While  physics
doesn't have a problem with time travel, our brains do. We  have  lived  our
entire lives in a universe where time moves  forward  and  not  back,  where
causes precede effects, and  where  the  future  presents  vast,  unknowable
possibilities. But perhaps someday that will all change. In fact, I know  it
will.



     THE FIFTH FORCE


     Just as the early Greeks broke the world down into just four  different
elements, so scientists have  found  that  all  observed  phenomena  in  the
universe arise from just four underlying forces. If we want to  imagine  the
Force as a force-and the name certainly fits-then either one or more of  the
four forces need to be responsible for the phenomena we see, or  there  must
be a fifth force that hasn't yet been detected by scientists. What  are  the
four forces that govern our universe?

     Two of them work only on tiny, atomic scales. The strong nuclear  force
holds together positively charged protons and neutral neutrons in the nuclei
of atoms. The weak nuclear force controls the radioactive  decay  of  atoms.
The other two forces can operate on larger scales. Electromagnetism attracts
negatively charged electrons and positively charged protons to  each  other,
creating atoms and molecules and so all matter. Gravity governs all  matter,
drawing it  together,  creating  the  structure  of  our  solar  system  and
universe. Scientists have long sought to unify the four theories  explaining
the workings of these four forces into one grand unified field theory.

     Such a theory would reveal that these four forces are simply  different
manifestations of one underlying force, and there are some indications  that
this is so. Quantum field theory is now able to describe three of  the  four
forces-all except gravity, which, although  it  may  not  seem  so,  is  the
weakest force. Gravity remains difficult to incorporate into a unified field
theory. Superstring theory , which we discussed in Chapter  4,  attempts  to
unite all four, though its work is incomplete. Yet even expressions  of  one
underlying force, could that one force be the Force?

     This unified force acts on us at all times. It acts on  every  particle
in every atom in our  bodies.  And  on  every  particle  in  every  atom  in
everything else in the universe. You could certainly say that it  "surrounds
us and penetrates us; it binds the galaxy together ." And you would be quite
accurate. But could this unified force do what the  Force  is  said  to  do?
Unfortunately, these forces, which we understand pretty well, can't convince
a stormtrooper that you're innocent, allow you  to  sense  the  presence  of
another Jedi, or bring you visions of the future .

     In addition, accessing these forces, just like accessing the energy  of
particles, isn't as easy as thinking about it. Remember that in this view of
the universe, particles are simply areas  of  high  concentration  of  field
lines. Thus we might As Luke As Luke accesses the energy in these fields  to
levitate Artoo, he is moving these fields. Thus the particles of  the  tree,
which embody the strongest points of the fields, should move  as  well.  Yet
the particles of the tree are not moving.  This  is  one  of  the  strangest
qualities of the Force. Imagine, for  example,  removing  the  gravitational
field from the moon! (In fact, I've got a  bridge  in  Brooklyn  whose  weak
nuclear forces I'd like to sell you.) Certainly these forces can  be  tapped
and their energy transferred from one place  to  another.  I  can  think  of
several ways to use the four forces in a tree to levitate my little droid. I
could cut down the tree, make boards out of it, and create a lever  to  lift
my droid.

     In essence I'm using the electrical forces between the particles in the
atoms of wood, which hold the wood together and make it feel hard,  to  lift
the droid. I could also create an atom bomb using the matter  in  the  tree,
and the weak nuclear force triggered would create an  explosion  that  would
certainly levitate Artoo, right off of Dagobah! Yet in  both  cases  we  are
manipulating the matter that embodies the concentrated energy of the  field.
None of the forces we know of could behave the way the Force  does.  So  the
Force would have to be an as-yet-undiscovered fifth force.  Is  it  possible
that we've missed another force in the universe ? Most scientists agree that
there probably are undiscovered forces in the universe.

     Dr. Visser finds this reasonable. "It's not at all unlikely that  there
might be more than the standard four forces around. The fifth one would have
to be pretty weak and satisfy  some  pretty  tight  constraints."  Since  we
haven't yet detected such a force, scientists believe it must only act  over
very short, subatomic distances. Physicists have been searching for a  fifth
force, and several have even reported discovering one.  But  those  reports,
thus far, have been disproven or remain unconfirmed. Such weak, short- range
forces, though, would be unable to have the powers we see the Force  having,
such as transmitting information long distances. Even if there  was  such  a
force, a "disturbance in the Force" could only travel at best at  the  speed
of light.

     If Alderaan, many light-years away, is blown to bits, the gravitational
field lines will shift as this large mass shoots out in all directions. That
shift in gravity will propagate out from the source of the disturbance in  a
wave traveling at the speed  of  light.  The  word  "disturbance"  seems  to
suggest a similar wave, like that caused when a  stone  is  dropped  into  a
pond. So Obi-Wan, on  the  Millennium  Falcon,  could  not  know  about  the
destruction of the planet instantaneously.

     Yet he does. It seems as  if  the  disturbance  in  the  Force  happens
everywhere at once. This violates our understanding of the universe  at  the
most fundamental level. While an unknown force or  particles  of  some  kind
might offer possible explanations for some of the  powers  of  a  Jedi,  the
Force presents us with a more  fundamental  scientific  problem.  The  Force
suggests a universe quite different than the one we think we're  living  in.
And it seems equally inexplicable to the  more  advanced  scientists  in  "a
galaxy far, far away." The Force  is  treated  as  a  mystical  religion  or
superstition, not a scientific  reality.  Which  suggests  it  is  something
radically different than anything yet discovered .

     "If the Force is tangible and they don't have a command  of  it,"  Marc
Millis says, "it must be a completely different phenomenon  ."  Dr.  Visser,
research associate professor at Washington University in St. Louis,  agrees.
"I'm not even sure if it would fit into physics or biology." So where do  we
go from here?



     WHERE JEDI FEAR TO TREAD


     In trying to explain  any  phenomenon,  once  science's  two  views  of
reality have been considered and no answer found, we have  to  consider  the
third option: that reality may be different than we believe.  The  Force  is
said to  connect  all  living  things,  and  this  connection  doesn't  seem
dependent on space, or even  time.  Obi-Wan  knows  instantaneously  of  the
deaths of the inhabitants of Alderaan . Yoda  seems  able  to  "watch"  Luke
growing up on Tatooine from light-years away on  Dagobah,  when  any  signal
should take years to travel from Tatooine to Dagobah. Luke is even  able  to
see the future. These events defy our basic understanding of  the  universe.
Scientists have long believed  in  the  principle  of  local  causality,  or
locality, that an object can only be affected by something adjacent  to  it.
If I have a mile-long line of dominoes set up, and I tip over the first one,
the last one can feel no immediate effect.

     It will not instantaneously fall over. The first one, instead, will tip
over the one adjacent to it, which will tip over  the  next  and  the  next,
following the principle of locality. Only after this process has had time to
travel from one end to the other will the second-to-last domino finally fall
over and tip over the last domino. The speed at which this effect,  or  this
signal, will travel that one mile depends on the nature of the signal,  with
the maximum speed possible the speed  of  light.  The  Force  thus  violates
locality.

     Connected to locality is independence. If locality is true,  then  each
particle is independent, influenced only by those things  in  its  immediate
vicinity. Since the Force connects all things in some instantaneous way that
transcends time and space, it  violates  independence  as  well.  The  Force
clearly allows Jedi  to  do  things  that  seem  impossible,  even  magical.
Fortunately, science provides a theory that allows for bizarre effects  that
seem magical, a theory that deals with a  realm  where  a  particle  doesn't
always act like a particle, where locality can appear to  be  violated,  and
where distant particles  sometimes  seem  connected  in  a  mysterious  way:
quantum mechanics , the theory that describes how the universe works at  the
subatomic level.


     Dr. Victor J. Stenger, professor of physics at the University of Hawaii
and author of The Unconscious Quantum, says,  "What  they're  talking  about
here is definitely a quantum notion . " Out of quantum theory has arisen the
controversial scientific hypothesis that most closely approaches an  overall
description of the Force. This  hypothesis,  the  causal  interpretation  of
quantum mechanics, was put forward by physicist David Bohm, a former protege
of Einstein's, in

     1952. Dr. Bohm modified and refined his interpretation up until he died
a few years  ago.  His  causal  interpretation  violates  the  principle  of
locality, just as the Force does,  and  suggests  that  all  things  in  the
universe are interconnected and unified on some deeper level of reality.


     Dr. Bohm had a lifelong  desire  to  understand  and  describe  all  of
reality, and he was troubled and intrigued by some of  the  implications  of
quantum theory. Most scientists have preferred the Copenhagen interpretation
of quantum theory, originated by Danish physicist Niels Bohr, rejecting  Dr.
Bohm's interpretation. Yet in recent years Bohm's work  has  been  receiving
renewed attention and consideration. You may be wondering how  we  can  have
different interpretations  of  a  theory.  Shouldn't  a  theory  describe  a
physical process without any ambiguity? But in the case of  quantum  theory,
interpretation is key. The theory clearly tells  us  what  results  we  will
measure in different experimental situations, and its predictions have  been
proven accurate.

     Yet exactly what these results imply about the  underlying  reality  is
unclear. Just as we know inertia exists but we're not sure what  causes  it,
so we know quantum effects exist, but we're not sure how they're created. In
the attempt to explain how, the standard Copenhagen interpretation  provides
a picture of subatomic reality quite different than what we're familiar  and
comfortable with in our larger-scale existence. Scientists have for the most
part accepted these strange implications, but many have done  so  only  with
reluctance, and others, like Bohm, offer alternate interpretations  of  what
this theory actually implies about reality. Although quantum theory has been
around for more than seventy years, scientists are still arguing about  what
it means.

     Dr. Visser believes the debate is growing ever more active. "There's  a
lot of speculation going around in  the  foundations  of  quantum  physics."
Einstein  was  also  troubled  by  quantum  theory,  particularly   by   the
interconnectedness of subatomic particles that seems to violate locality and
independence  and  create  what  Einstein  called  a  "spooky  action  at  a
distance." With his colleagues, he explored this "spooky action," which  may
be similar to what we see with the Force. Their argument became known as the
EinsteinPodolsky -Rosen paradox, or EPR paradox.

     To understand their argument, let's quickly review some of  the  basics
of quantum mechanics. Don't worry. This will only hurt for a couple minutes.
It may twist your brain a bit, but to paraphrase my little green friend (no,
not my iguana Igmoe), if you want to understand the Force, you must complete
your training. So stick  with  me  on  this.  According  to  the  Copenhagen
interpretation of quantum mechanics , subatomic particles, such as electrons
or photons, can behave either like particles or like waves, depending on how
we look  at  them.  In  fact,  all  matter  has  particlelike  and  wavelike
properties , though the wavelike properties of larger objects are too  small
to be measured.

     Just as Princess Leia speaks with a British accent when around Imperial
officials and with an American accent when with  friends,  the  behavior  of
these quantum particles depends on the circumstances  in  which  we  observe
them. The second element  of  quantum  theory,  the  Heisenberg  uncertainty
principle, We discussed briefly in  Chapter  4  in  connection  with  vacuum
fluctuations. if you recall, this principle tells  us  that  the  amount  of
information we can gather about a very tiny object  is  limited,  since  the
simple act of measuring disrupts the object.

     Specifically, we can't measure both the position and the velocity of  a
subatomic particle with  complete  accuracy.  We  can't  reach  an  accuracy
greater than that of Planck's constant. While Planck's constant is  a  tiny,
tiny number, meaning we can be quite accurate on  human-scale  measurements,
this tiny number becomes a significant limitation when we attempt to measure
quantities on the quantum scale. How does measuring a particle  disrupt  it?
To measure the position of an object, we have to shoot  a  photon  or  other
particle at it. The photon will be bounced or reflected back at us,  and  we
can then "see" or measure the object in question.

     For example, we might shine a flashlight into a dark room to  find  the
position of Jabba the Hutt. Measuring the position of Jabba the Hutt  is  no
problem, since a few photons aren't going to disturb his blubbery frame. But
measuring the position of an  electron  does  pose  a  problem  .  Since  an
electron is so small, the photons from the flashlight will  disturb  it.  We
may get an accurate measurement of its position , but its velocity  will  be
radically changed, so we can never know what it was. Or  using  a  different
technique, we might measure  its  velocity,  but  in  doing  so  change  its
position. So quantum theory tells us that we can't  know  exactly  where  an
electron is and what it is  doing.  But  what  does  that  imply  about  the
underlying reality?

     What is that electron  really  up  to?  The  Copenhagen  interpretation
states that since an electron's position is unmeasurable,  it  is  therefore
meaningless. But more than  that,  the  interpretation  tells  us  that  the
particle doesn't have an exact position or velocity until we measure it. The
uncertainty of our measurement is not just some peculiarity of the measuring
process but an intrinsic property of subatomic particles. How can a particle
not have an exact position? This goes back to the  first  piece  of  quantum
theory, that a particle is actually misnamed. It may act  at  times  like  a
particle and at times like a wave, but the most accurate way to describe  it
is as a wave packet,  a  localized  disturbance  whose  state  is  described
mathematically by something called a wave function. The wave function  gives
the probabilities that the particle will be in various states or positions.

     We like to think of a hydrogen atom as an electron orbiting a proton  ,
like a planet orbiting the sun. But the electron's movement is not nearly so
neat. According to the Copenhagen interpretation, the electron has different
probabilities of being in different positions . If we envision the  electron
as Princess Leia, we could say, "She might be in the Hoth command center, or
she might be near the Millennium Falcon." We do not know exactly  where  she
is. And more than that,  she  is  not  exactly  anywhere.  She  is  in  what
physicists call "a superposition of  states"  in  which  her  wave  function
encompasses both of these places as possibilities. In addition to  being  in
no particular place,  the  electron  does  not  follow  a  clear  trajectory
governed by the forces acting on it,  like  a  planet  around  the  sun,  or
Princess Leia, getting mad at Han Solo and stomping away from the Millennium
Falcon to visit the command center.

     As Bohm said, "It is assumed that in  any  particular  experiment,  the
precise result that will be obtained is completely arbitrary  in  the  sense
that it has no relationship whatever to anything else  that  exists  in  the
world or that ever has existed." In essence, the particle's position is  not
determined by specific  causes  or  forces.  This  violates  the  scientific
principle of determinism , which says that a particle's position  and  state
are absolutely determined by the forces acting upon it. So it's not only the
Force  violating  beloved  scientific  principles;   the   widely   accepted
Copenhagen interpretation of quantum theory does as well. What happens  when
we measure the position of the electron, or  Princess  Leia?  Measuring,  or
observing, has a powerful effect in quantum theory. This is  the  third  and
final piece of quantum theory you need to know.

     Before we measure its location, the electron is potentially present  in
many different places at once, but actually present in none. When we measure
it, the electron simply appears in one of the places encompassed by its wave
function, without any clear cause determining the particular place. We  find
Leia in the command center, for no particular reason. We have, in the act of
measuring, eliminated the  possibility  that  she  is  near  the  Millennium
Falcon. Similarly, we would find  the  electron  in  a  specific  place  and
eliminate the possibility that it is in any other place. As physicists  say,
we have "collapsed" the wave function , eliminating other possibilities  and
localizing the wave packet, making it take on the properties of a particle.

     As Dr.  Nick  Herbert  ,  author  of  Quantum  Reality,  describes  it,
"Everything we touch  turns  to  matter."  Dr.  Stenger  compares  the  wave
function to the lottery. Before the winning lottery  number  is  chosen,  or
observed, you have a .00001 percent chance of winning. You could win or  you
could lose-though losing is a lot more likely. When the  lottery  number  is
chosen, the probability "collapses." Either you win or you lose. Only one of
the possibilities remains as actuality. The requirement that we must observe
a particle for it to exist in a specific place  means  that-at  the  quantum
level, anyway-no objective reality exists.

     A particle must be observed, a subjective process, in order  to  exist.
Many scientists have rebelled against the idea  that  no  objective  reality
exists, since objective reality is  exactly  what  science  is  supposed  to
describe. This aspect of  the  Copenhagen  interpretation,  along  with  its
violation  of  determinism,  has  struck  many  scientists  as  absurd   and
unacceptable. Yet in the absence of a  completely  articulated  alternative,
the Copenhagen interpretation has become accepted.

     You need just one other piece of information before we can discuss  the
EPR paradox. Many elementary particles, including electrons, have a  quality
called spin, which reflects the particle's angular momentum. These particles
don't actually spin the way the Earth spins on its axis-nothing  in  quantum
mechanics is easy to visualize-but we can  imagine  them  that  way  without
getting into too much trouble. Quantum theory allows that electrons can have
only two possible spins with equal and opposite angular momenta  .  This  is
comparable to imagining that the electron can spin at only one speed, yet it
may spin either clockwise or counterclockwise .

     These options are called spin up or spin down. The wave function of  an
electron, then, may show that it has a 50 percent chance of having  spin  up
down. Just as with the position discussed above, the  electron  has  neither
spin, like a coin tossed up and frozen in midair has a  50  percent  landing
with heads up and a 50 percent chance of landing  with  tails  up.  When  we
measure the electron, though, we force  it  to  display  one  of  these  two
options. If we think of  our  coin  frozen  in  midair,  the  equivalent  of
measuring the electron is unfreezing time and forcing the coin to  land,  so
that we can measure either heads or tails. If we measure, say, spin up, then
the wave function no longer has a 50-50 chance of either spin.  It  now  has
only a 100 percent chance to have spin up.

     Now let's explore the EPR paradox that bothered Einstein  so  much,  in
which an event at one point  instantaneously  affects  an  event  at  a  far
distant point, violating  locality  and  independence  as  the  Force  does.
Imagine we have two electrons. We can create a system  in  which  the  total
spin of the two electrons must be zero. This means that if one electron  has
spin up, the other must have spin down. The two electrons  are,  in  physics
terms, entangled: the state of one affects the state of the other. Thus  the
wave function of the two electrons reveals two possibilities: there is a  50
percent chance of electron 1 having spin up and electron 2 having spin down,
and a 50 percent chance of electron 1 having spin down and 50 percent chance
of electron 1 having spin down and electron 2 having spin up.

     Other scientists drew different conclusions. Dr.  Bohr,  originator  of
the Copenhagen interpretation, maintained  that  since  quantities  such  as
position or spin are meaningless until they are measured,  we  can  have  no
knowledge of  what  is  going  on  between  the  two  particles  before  the
measurement is made. Therefore we can draw no conclusions about whether  any
"spooky action" has occurred. While most  physicists  were  shocked  by  the
implications of the EPR paradox, just as they had  been  with  many  of  the
implications of quantum theory, they eventually found  an  explanation  they
could live with. Scientists stress that the  above  scenario  doesn't  truly
violate the prohibition that no signal can travel faster than the  speed  of
light, since this situation does not allow us to  transmit  any  information
from one location to another.

     Although the electrons may be in  faster-than-light  communication,  we
cannot use this phenomenon to send a  warning  message  to  Wedge.  He  will
either find the electron has spin up or down, and we can't control which. If
this explanation strikes you as very weak, join the club.  Dr.  Bohm  agreed
with Einstein that the Copenhagen interpretation was  incomplete,  and  that
there must be hidden variables we don't yet understand determining the spins
of the particles. Thus there is not really a 50-50 chance  of  each  result,
but only one possible result; we simply lack the information to deduce which
result this is  without  measuring  it.  This  idea,  that  the  results  of
measurements are not simply based on probabilities  but  are  determined  by
causes  and  forces  we  don't  yet   understand,   underlies   the   causal
interpretation of quantum theory, put forward by Bohm.

     If Leia is in the command center on Hoth, then it is not due to  chance
but because she was previously at the Millennium Falcon  and  Han  sent  her
stomping angrily toward the command center. The positions , velocities,  and
spins of particles are completely determined by their previous state and the
forces acting upon them. Bohm's interpretation preserved determinism, unlike
the Copenhagen interpretation . Yet Bohm believed the EPR  paradox  revealed
that locality could be violated. Instead of trying to  explain  the  paradox
away, he saw it as a sign that the universe is connected on some  underlying
level. In his view, the two electrons are not two separate  particles;  they
are one single entity or wave function. Going back to our coin  analogy,  we
might think of the two electrons as the two faces of the coin. If  heads  is
facing up, tails must be facing down. The two faces are entangled. Might  we
not  all  be  part  of  some  cosmic  wave  function,  all   entangled   and
interconnected? This is the question Bohm asked, and the answer, if we  pose
it to Obi-Wan, would clearly be yes.

     He is entangled with the people of Alderaan; he is entangled  with  all
things. The destruction of Alderaan has an immediate effect on  him.  If  we
ask most scientists, though, we'll get  a  somewhat  different  answer.  The
accepted answer is that entanglement occurs only on a microscopic scale, and
not on the macroscopic scale of our experience. As Dr. Kaku says, "According
to standard quantum mechanics, there  is  a  wall  separating  us  from  the
microcosm." Yet these subatomic particles are part of our world, and so  any
weird behavior they exhibit affects us as well. In fact,  we  can  construct
some bizarre situations in which microscopic events  become  entangled  with
macroscopic ones. The oddest of them  all  is  Schro:dinger's  cat  paradox,
which Dr. Erwin Schro:dinger articulated to reveal  how  ridiculous  quantum
theory could be. In our case, we'll call this  the  Princess  Leia  paradox.
Leia, by the way, is now playing herself, not an electron. The  princess  is
knocked unconscious and placed inside a sealed cell in the  detention  block
of the Death Star. A blaster is aimed at her. The blaster is connected to  a
radium atom. Radium is radioactive and will eventually decay. Imagine it has
a 50 percent chance of decaying within one hour. When it does decay, it will
trigger the blaster and Leia will be shot. The wave function of the  radium,
then, is a superposition of two possible states:  the  state  in  which  the
radium atom has not yet decayed, and the  state  in  which  it  has  already
decayed.

     Similarly, Princess Leia is then also  described  by  a  wave  function
encompassing two possible states: one in which she  has  been  shot  and  is
dead, and one in which she has not been shot and is  alive.  The  Copenhagen
interpretation states that until Luke opens the door to  the  cell  an  hour
later and observes Leia, she is neither alive nor dead. Instead, she is in a
superposition  of  states,  each  having  a  50  percent   possibility.   An
observation is necessary to collapse the wave function and put  her  in  one
state or the other.

     Luke must open the door and look inside for Leia to be either  dead  or
alive. Dr. Erwin Schredinger Schro:dinger believed this paradox  revealed  a
critical  weakness  in  the  Copenhagen  interpretation.  Einstein   agreed,
pointing out the silliness of quantum theory by saying, "Does the moon exist
just because a mouse looks  at  it?"  Again,  we  are  confronted  with  the
Copenhagen interpretation's conclusion that no objective reality exists, and
not only on the quantum level, but sometimes also on the larger scale of our
own lives. Scientists have struggled to find some way in which Leia  can  be
either dead or alive without Luke having to open the door to look at her.

     The majority of scientists evade  this  requirement  for  an  observing
consciousness by saying that a living observer is  not  required,  simply  a
measuring device of some kind. Others, like Dr. Kaku, believe that  each  of
these possibilities occurs, splitting the universe into  two  universes.  In
one universe Leia is alive; in another she is dead. Each time an observation
is made and we see a specific outcome,  the  universe  splits  into  several
alternate universes , one in which  each  possibility  occurs,  creating  an
infinity of universes. According to this  theory,  these  universes  do  not
communicate with each other, so there is no way to prove  or  disprove  that
they exist.

     Yet this  "many  worlds"  interpretation  still  requires  us  to  make
measurements or observations in order to, in essence, "create" our  reality.
There  is  no  objective  reality  in  these  interpretations  .  The   only
interpretation  that  provides  for  objective  reality  is  Bohm's   causal
interpretation, in which hidden forces determine  whether  an  electron  has
spin up or down, whether a radium atom decays or not, and  whether  Leia  is
alive or dead. Whether Luke opens the door or not, these hidden forces  will
have already acted on the radium atom and determined  the  situation  inside
the cell. Leia will not be in some superposition of  states.  Leia  will  be
either alive or dead.

     And the result will not  be  determined  merely  by  chance,  like  the
drawing of a lottery ticket. According to Bohm, our inability  to  determine
the cause of these various events does not mean there is no cause. This idea
of hidden forces led Bohm to differ with the  Copenhagen  interpretation  in
other ways as well. Bohm theorized that particles are always  particles  and
never waves. There is no wave function that must be collapsed by an observer
for a particle to manifest itself. And each particle always has  a  specific
location, momentum, and spin. We might not know these quantities because  of
our failure to understand the hidden factors or forces controlling them, but
they do have specific values. This certainly agrees more with  our  everyday
experience of reality. And Bohm's causal interpretation is  consistent  with
experimental results. "Some of what Bohm did was absolutely beautiful,"  Dr.
Visser says. "He showed that you can build a hidden variables theory and  it
works and agrees with experimental physics just as well as the Copenhagen or
many worlds interpretations."

     Bohm's interpretation  raises  a  challenging  question,  though.  What
exactly are these hidden forces that control the movement of every  particle
in the universe? Dr. Bohm posited the existence of a fifth force, a  quantum
potential force field that pervades all space. The weird effects of  quantum
mechanics arise because each particle is accompanied and governed by a  wave
in this quantum potential field. Just as an electron is  always  accompanied
by an electric field,  an  electron  is  also  accompanied  by  the  quantum
potential field. This quantum potential wave is not like the  wave  function
of the  Copenhagen  interpretation,  a  mathematical  construct  that  gives
probabilities. It's part of a physical force  field,  like  a  gravitational
field, that affects the course of particles. Since we don't  understand  the
workings of this force, we can't yet calculate the trajectory of  particles.
But if we someday understand it, then we can. Bohm theorized that this force
does not decrease with distance ,  unlike  other  forces,  thus  helping  to
explain long-distance effects as in the EPR paradox.

     In that situation, a single quantum potential  wave  controls  the  two
entangled particles, no matter how far apart they go. Measuring a  property,
such as the spin of one particle, instantaneously alters the  shape  of  the
wave, affecting the  other  particle  under  its  control.  So  the  quantum
potential force violates both locality and independence, just as  the  Force
does.  The  fact  that  the  quantum  potential  field  conveys  any  change
instantaneously over all of space suggests that it carries information about
the whole universe. Dr. Bohm compared the relationship between  the  quantum
potential force and a particle with the relationship between  a  radio  wave
and a ship set on automatic pilot to be guided by those radio waves.

     The radio waves are not pushing the ship, but they provide  information
that directs the movement of the ship. Similar, one could say,  to  the  way
the Force is said to control one's actions. But could this quantum potential
force be the Force? At the least it has several qualities in common.  First,
they are both nonlocal  .  Dr.  Stenger  confirms  the  Force  is  nonlocal,
describing it as "holistic. It's a continuous field throughout the  universe
that acts instantaneously throughout  the  universe."  Second,  the  quantum
potential field is not created by  or  concentrated  around  matter,  unlike
other forces. The quantum  potential  force  guides  particles  but  is  not
generated by them, just as the radio waves are not generated  by  the  ship.
They simply steer the ship.

     So while we had a  hard  time  imagining  how  Luke  could  remove  the
gravitational force from the Moon and use it to  levitate  Artoo,  we  might
imagine Luke gathering and directing the quantum potential somehow,  sending
signals that "steer" Artoo up into the air of Dagobah.  Third,  because  the
quantum potential force permeates all space and is not affected by distance,
it in essence entangles or interconnects all particles. In Bohm's view,  the
universe  is  not  a  collection  of  objects,  but  a  web   of   vibrating
interconnected patterns governed by this quantum potential force.

     This sounds quite like the view of the universe presented by Yoda.  Dr.
Visser agrees. "If Bohm is right, if this  quantum  potential  exists,  then
maybe it is the  appropriate  framework  for  doing  the  things  the  Force
allows." Aside from its basic properties, we know  very  little  about  what
this quantum potential force might be like. One  possibility,  according  to
Bohm, is that this field may be one and the same as the zero-point field  we
discussed before. Dr. Puthoff says, "I do think maybe they're the same thing
in different clothing."

     If this is so, then we at least have a sense of how strong the  quantum
potential is and how it's generated. Is  Bohm's  causal  interpretation  the
right one, though? Does the quantum potential force really exist? Since both
the causal interpretation and the Copenhagen  interpretation  predict,  with
only a few exceptions, the same experimental results, those results  support
both  interpretations  equally.  While  Dr.  Stenger   finds   Bohm's   work
interesting, he  feels  that  all  experimental  results  can  be  explained
satisfactorily by the Copenhagen interpretation.  "There  are  no  phenomena
that you need this to explain."

     He obviously hasn't seen Yoda levitate an X-wing out of  a  swamp.  But
what about those few exceptions where  the  causal  interpretation  predicts
different results  than  the  Copenhagen  interpretation?  Thus  far,  those
differences have proven impossible to measure. After all, how can  we  check
whether Leia is alive or dead before we observe her, unless we observe  her?
Most scientists object to Bohm's idea of the quantum potential force on  two
grounds, the very qualities the quantum potential has  in  common  with  the
Force.

     First, unlike the other forces, the quantum potential appears  to  have
no known physical source.

     Second , unlike the other forces, the quantum potential force  violates
locality. If we are to go along with the current accepted wisdom, then  both
the quantum field and the Force are unlikely. Yet  if  we  consider,  as  an
increasing number of scientists are now doing, that  the  quantum  potential
offers an alternative explanation of experimental results, then it  seems  a
valid possibility. And by considering how it may operate, we can learn  more
about what the Force might be like. From this point on,  our  discussion  of
the causal interpretation of quantum theory becomes less scientific and more
philosophical. The evidence can take  us  no  farther.  All  we  can  do  is
speculate about what the existence of  the  quantum  potential  might  imply
about the nature of reality.

     Yet it is in this no-man's-land between science and philosophy that  we
may find the Force. "In a sense," Dr. Visser says, "the Force  seems  to  be
taking the notion of God and religion and philosophy and putting it  into  a
quasi-scientific setting." Just as Einstein explained that  space  and  time
are interconnected as part of a space-time continuum, Dr. Bohm believed that
everything is connected as part of  a  single  continuum,  that  the  entire
universe is one  single,  complex  entity.  Just  as  superstring  theorists
believe the four forces may be projections of a  single  su-  perforce  that
exists in ten higher-dimensional reality.

     Earlier, we discussed how two entangled electrons might be  thought  of
as one single entity, like the two faces of one coin. Bohm used  a  slightly
different example that illustrates how additional dimensions  might  contain
the key to the behavior we observe . As we  know,  it's  very  difficult  to
imagine more dimensions, so let's pretend that we live  in  two  dimensions.
Now let's set up our thought experiment. Imagine an  aquarium  with  a  fish
inside. We put one video camera at the end of the aquarium, and the other on
the side of the aquarium.

     The aquarium and the fish exist in three- dimensional space. But in our
two-dimensional world, all we can see are the images  on  the  two  flat  TV
screens displaying what the two cameras are recording. If the fish is facing
the end of the aquarium , on one screen we'd see a tall, very thin creature.
On the other screen we'd see an equally tall yet very wide  figure.  Imagine
now the fish turns to the side of the aquarium. On  the  first  screen,  the
thin creature now becomes  wide,  while  on  the  second  screen,  the  wide
creature becomes thin. As we observe this, we realize that the  change  from
thin to wide on one screen is always accompanied by a change  from  wide  to
thin on the other screen. Just as in the EPR paradox,  one  electron  having
spin up is always associated with the other having spin down. If  we  didn't
know that these two images showed the same fish, we would wonder  how  these
changes were coordinated.

     They happen instantaneously, no  matter  how  far  apart  the  the  two
screens are, violating locality. The two images seem to communicate  through
some faster-than-light method. The truth, though, is that these  two  images
are not communicating instantaneously. They  are  simply  projections  of  a
single three-dimensional reality.

     Similarly, Bohm believed the two entangled electrons are  facets  of  a
single underlying reality that we are not able to perceive in its  entirety.
This again relates to what we are told about the Force. Yoda suggests that a
greater reality exists beyond whatwe see, explaining, "Luminous  beings  are
we. Not this crude matter."

     Bohm believed that underlying the apparently  chaotic  physical  realm,
this higher-dimensional reality holds a hidden or enfolded  order.  Applying
this to the quantum realm, he proposed that the hidden order  is  maintained
by the quantum potential force, which controls and connects all things. Bohm
used the hologram as an analogy to explain this underlying order.

     We discussed in  Chapter  4  how  a  laser  emits  light  of  a  single
wavelength that is in phase. A hologram, in a sense, is  like  a  photograph
taken with a laser. It's created by splitting the laser beam into two beams.
One beam is bounced off the object to be "photographed" and onto a piece  of
film. The second beam goes directly from the laser to the film, not touching
the object, and mixes with the first. The two beams are now  out  of  phase,
and as they come together they create an interference pattern on  the  film.
If you want to see what  an  interference  pattern  looks  like,  fill  your
kitchen sink with water.

     Hold your hands over the water about a foot apart and  tap  your  index
fingers regularly into the water. You will see a series of circular  ripples
emanating from each of your  fingers.  As  these  ripples  meet,  they  will
interfere with each other. If one peak meets with another  peak,  they  will
interfere constructively, creating a higher peak than either original. If  a
peak meets a trough, they will interfere destructively, canceling each other
out. The result is a complex pattern of peaks and troughs. Holographic  film
holds a similar image. Unlike a regular photographic negative, the film does
not have an image of the object photographed.

     It looks more like a web of rings and ripples,  apparently  random  and
chaotic. Yet when laser light is shone through the film,  like  light  being
sent through a slide, the three-dimensional image of the original object  is
projected, just like the image of Princess Leia  that  Artoo  projects.  The
interference pattern on the film contains encoded or enfolded within it  the
image of the object that created it. Shining a light on the hologram unfolds
the structure to reveal the image of the  object.  For  Bohm,  the  hologram
embodied the notion that within something that seems random and  disordered,
like the image on the holographic film, order is hidden  or  enfolded,  like
the image of the photographed object.

     And there's another property of the hologram that reflects Bohm's  view
of the universe. If you cut a hologram into pieces and illuminate  just  one
piece with a laser bream, you will see  not  a  piece  of  the  photographed
object but the entire object. The image will have lost some  sharpness,  but
still the entire image will be there. Thus in each piece  of  the  hologram,
the image of the whole is enfolded. Similarly, Bohm believed that "The whole
universe is in some way enfolded  in  everything  and  that  each  thing  is
enfolded in the whole."

     This reflects the interconnectedness implied by the Force and  suggests
how Obi-Wan might instantaneously know of the deaths of those  on  Alderaan.
If a hologram represents the apparent chaos of the physical world, we  might
then imagine that the Force is the light through the hologram.  If  you  are
trained in the Force, you can see through  the  seemingly  chaotic  physical
world to the true order and nature enfolded in the universe. In  fact,  this
order and nature is enfolded within you, and by becoming calm, at peace, you
can unfold that universe within.

     You are everything- the rock, the tree, the  planet,  all  people,  the
universe. You observe this order and are a part of it. You are connected  to
all things. Thus science,  through  the  causal  interpretation  of  quantum
theory, provides us with an image of the universe very much  like  that  the
Force suggests, and with a  model  of  a  force  that  shares  many  of  the
properties of the Force.



     IT'S ALL IN YOUR MIND


     The one key difference between the causal interpretation and the  Force
is control. Jedi are not simply under the control of  the  Force;  they  can
also control it. Yet Bohm believed everything is under the  control  of  the
quantum potential force. The quantum potential is the cause determining  the
position of every particle. A human consciousness is just one piece  of  the
unified universe, and does not have any special power that a rock or a  tree
would not have. as everything else.

     Dr. Puthoff explains that  in  Bohm's  view,  "Everything  is  cast  in
concrete." The cost of creating a universe in which everything is  connected
through a single, controlling force is that we lose the  ability  to  affect
this universe. Dr. Visser finds this ability of Jedi to  control  the  Force
with their minds the most difficult trait to understand. "It's  supposed  to
couple to people's minds. The four forces of physics  couple  to  individual
atoms and the body. It's not clear at all how you  would  set  up  something
that would couple to the mind rather than the body. "

     To find a universe in which we can  affect  quantum  reality  with  our
minds, we must give up the idea that everything is connected and  return  to
the  concept  of  locality.  This  takes   us   back   to   the   Copenhagen
interpretation. In the  Copenhagen  interpretation,  consciousness  plays  a
special role. It is necessary to  collapse  the  wave  function  and  so  to
"create" reality. While the vast majority of scientists believe a  measuring
device can serve the same purpose , some believe  a  conscious  observer  is
required, the mind playing some special role in this process.

     Dr. Henry Stapp at the University of California at Berkeley is  one  of
those who believes consciousness holds a special place in the  universe.  In
his theory, based on the Copenhagen interpretation , a measuring  device  is
not sufficient to collapse the wave function . Let's go back to  the  sealed
cell with Princess Leia and the blaster. The blaster, remember,  is  set  to
fire if a radium atom decays , which it has a 50  percent  chance  of  doing
within an hour. Leia remains in a superposition of  dead  and  alive  states
until an observation is made and her wave function collapses. At the end  of
the hour, instead of sending Luke in to observe  Leia,  we  instead  send  a
droid-cam.

     The droid-cam enters and records what it finds. Most  scientists  would
believe this recording or measurement is sufficient of the radium  particle,
and so to put Leia into a state in which she is definitely  alive  or  dead.
But Dr. Stapp believes a conscious observer must read the  measurements,  or
watch the recording, in order to collapse the wave function. If this is  so,
then the recording made by the droidcam has now become  entangled  with  the
radium atom and Princess Leia.  Its  recording  is  in  a  superposition  of
states: one in which its recording shows Leia  has  been  shot,  another  in
which the recording shows Leia is fine.

     Similarly, when the droid-cam plays the  recording  for  Luke,  he  too
becomes entangled in this mess. Yet for some reason, he does not go  into  a
superposition of states, one in which he has seen a recording of  Leia  dead
and one alive. Instead, as his server become entangled with the atoms  being
observed, a special opportunity is created: mind and matter can interact. He
has even theorized that an additional term is required in the  equations  of
quantum theory, a term that reflects this entanglement of  the  observer  's
brain and the  observed  particles.  If  such  a  term  is  valid  in  these
equations, not only could the human mind collapse the wave function, but  it
could potentially affect how it  collapses-whether  Leia  will  be  dead  or
alive.

     Dr. Robert  Jahn,  director  of  the  Princeton  Engineering  Anomalies
Research Program, studies physical phenomena that appear to  correlate  with
conscious intention. He believes that his experimental  findings  require  a
science that "involves the human participant in  the  determination  of  the
results . This is obviously a radical departure from  conventional  physical
science."

     Before we go any further, I must stress  that  most  scientists  firmly
believe that the state into which a wave  function  collapses  is  merely  a
matter of probabilities and chance. Measuring or  observing  constrains  the
wave packet and so forces it into  a  particular  state,  but  measuring  or
observing cannot control into which state it goes. Dr. Stenger believes that
if we had such a power, we would have seen its effects long ago. "We have to
go by what we know, our established observations about the universe. What we
have is a theory that's been around for 93 years and never been found to  be
violated. That doesn't mean it won't be someday, but based on what we  know,
we can't make any such assumption." Those who would like to believe that the
mind  can  affect  reality  -for  example,  those   who   believe   in   the
paranormal-use the Copenhagen interpretation or theories like Dr. Stapp's to
help justify their beliefs.

     Dr. Stenger believes these ideas are very poorly based. "They  use  the
idea in the Copenhagen interpretation of quantum mechanics, that the reality
of a body doesn't come into being until you observe it. The  place  they  go
wrong is to assume that the kinds of effects that can occur at  the  quantum
level will occur at the macroscopic scale of  the  human  brain.  The  human
brain is a piece of classical machinery. Quantum mechanics has  very  little
to do with the human brain, or the human body as a whole.  We  need  quantum
mechanics to understand the chemicals in a rock, but that doesn't mean  that
rock is conscious." Yet some believe that theories like Dr. Stapp's indicate
that mind may influence matter on the quantum level. If the collapse of  the
wave function is due to some mind/particle interaction, they argue, then why
couldn't mind influence matter?

     Dr. Puthoff agrees with this  thinking.  "I  do  believe  consciousness
affects reality  .  "  What  led  Dr.  Stapp  to  his  radical  theory?  The
experiments of paranormal investigator Helmut Schmidt. Schmidt  generated  a
series of random  negative  and  positive  numbers  using  a  random  number
generator (RNG),  an  electronic  device  that  uses  radioactive  decay  to
generate a sequence of random numbers. As we  discussed  with  the  Princess
Leia paradox, the time of radioactive  decay  cannot  be  predicted,  so  it
serves as a good source of randomness . The RNG cycles over and over through
the possible numbers, like a person flipping through a deck of cards. At the
moment the radioactive decay occurs, the number currently in  the  cycle-the
card on top of the deck-is emitted by the machine.

     This can occur a few hundred times a second, so a  sequence  of  random
numbers can be quickly generated. Just as the radium  atom  in  Leia's  cell
determined whether the blaster shot her  or  not,  these  radioactive  atoms
determined which numbers were generated based on whether the  atoms  decayed
or not. Just as Leia's condition was recorded, the  numbers  generated  were
recorded. If Dr. Stapp's  theory  is  correct  and  this  recording  is  not
sufficient to collapse the wave function, then the recording would be  in  a
superposition of states, with many different  possible  lists  of  different
numbers. This recording would not collapse into a  single  list  of  numbers
until an observer looked at it. In Schmidt's experiment, no  one,  not  even
Schmidt, looked at the list of numbers for several months.

     Then the list was scrolled across an electronic display before a  class
of martial arts students.  The  students  were  asked  to  try  to  mentally
influence the display to show more positive numbers than negative ones.  The
numbers revealed were, indeed, more positive than negative, so much so  that
the results had less than a one-in-a-thousand chance of occurring at random.
Dr. Stapp theorizes that the numbers did not collapse to a single list until
observed by the students, and that their  mental  states  affected  how  the
numbers collapsed, making them more positive than negative. In essence,  the
students were influencing the radioactive decay  that  had  occurred  months
earlier.

     If this were possible, we could potentially transmit information in the
situation set up in the EPR paradox, information that  would  travel  faster
than the speed of light. In that  case,  we  had  two  electrons  that  were
entangled so that their spins had to be opposite each other. If we  measured
electron 1 with spin up, we knew electron 2 must have spin down. Electron  2
would somehow instantaneously "know" that electron 1 had been measured  with
spin up, even if it was  a  light-year  away.  The  way  physicists  explain
themselves out of this jam is that we can't use this phenomenon to  transmit
any information, so it doesn't really violate the light- speed limit.

     If Wedge measures the spin of electron 2, we can't  control  what  he's
going to measure. It will simply be the opposite of  whatever  we  measured.
But if we can control what we measure, by mentally influencing electron 1 to
have a particular spin, we can send a message to  Wedge.  We  could  arrange
with Wedge that if he measures the electron  to  have  spin  up,  he  should
attack the Empire by land, whereas if  he  measures  spin  down,  he  should
attack by sea. We could then, using our mental  powers,  make  our  electron
have spin up, so that Wedge's will have spin down, signaling him  to  attack
by sea. Believers in the  paranormal  view  experiments  like  Schmidt's  as
evidence that the mind can affect quantum events. And if that is true,  they
believe these quantum effects could  provide  the  mechanism  through  which
other  paranormal  powers  could  operate,  powers  such  as   clairvoyance,
telepathy, psychokinesis, and precognition . The very powers of the Force.

     Yet experiments testing paranormal powers are often not  as  definitive
as they might seem. While  Dr.  Stenger  respects  Dr.  Stapp's  attempt  to
quantify the  role  of  consciousness  in  equation  form,  he  finds  these
experimental results "fishy." Many different factors  play  a  role  in  the
validity of experimental results, and we'll go into these  more  later.  But
experiments testing the existence of these powers offer another approach  to
studying the Force. Whether we can explain it theoretically or not, have the
phenomena associated with the Force been observed?

     Does the Force really exist, right here on Earth?



     INVADERS FROM THE FOURTH DIMENSION


     If the Force exists, it may well exist in a  greater-dimensional  space
than we can perceive. Bohm's theory suggests that the  Force  may  exist  in
additional dimensions. Superstring theory similarly posits that our universe
may have ten  dimensions.  Whether  or  not  we  find  the  Force  in  these
additional  dimensions,  they  themselves  may  provide  us   with   amazing
abilities. In Chapter 4 we discussed how we might travel quickly across  the
galaxy by uncurling a collapsed dimension.  Just  as  we  imagined  using  a
higher dimension to shortcut through space, we might imagine using a  higher
dimension to gain the powers attributed to the Force. Carl Gauss, the famous
nineteenth-century  German  mathematician,  used  a  thought  experiment  to
clarify the effects of higher dimensions. He imagined "bookworms," creatures
that lived in only two  dimensions,  as  on  a  giant  sheet  of  paper.  As
three-dimensional people, we could peel a bookworm off the sheet  of  paper,
move him to another spot, and lay him  back  on  the  paper.  To  the  other
bookworms, it would appear that the  worm  in  question  vanished  and  then
magically reappeared elsewhere.

     Or we could slide the bookworm along the sheet, magically  "levitating"
him. From our perspective of height, we could watch  far-distant  events  in
bookworm land, such as what a young worm  named  Luke  is  doing.  A  sealed
bottle in bookworm land would simply be the outline of a bottle drawn on the
paper. If a secret message had been  sealed  inside  the  bottle,  we  could
easily lift it out and put it down elsewhere.  Dr.  Michio  Kaku  tells  the
story of psychic Henry Slade, who became famous in  late  nineteenth-century
London. Some of the top scientists of the day became  convinced  that  Slade
was accessing the "fourth dimension" during his seances to communicate  with
the dead and perform seemingly impossible tasks. He could take two separate,
unbroken wooden rings and intertwine them. He could also remove the contents
from a sealed bottle without breaking the seal or  the  bottle.  Such  tasks
could be accomplished if it was  somehow  possible  to  move  these  objects
through a higher dimension, but not in our world.

     The astounded scientists, of course, had been deceived  by  a  skillful
performer. But the fact remains, accessing higher dimensions could allow for
seemingly magical powers. Does this mean Yoda can access  higher  dimensions
to levitate objects and see events at great distances? Dr. Kaku admits  that
"such feats of


     <MISSED PART>


     ZEN AND THE ART OF NERF HERDING


     Of all the powers associated with the Force, the one that seems like it
would be the most fun is the ability to influence others. "You will take  me
to Harrison Ford now." If only. Using that "old Jedi  mind  trick,"  Obi-Wan
makes a storm- trooper believe R2-D2 and C-3PO are not the  renegade  droids
carrying the Death Star  plans,  and  Luke  makes  Jabba's  chief  aid,  the
tentacle-headed Bib Fortuna, admit him to Jabba's throne room. In both these
cases, those influenced repeat the words of the Jedi as if in a  trance  and
then carry out his wishes. Although this power isn't one we see  every  day,
it does resemble a phenomenon most of us are familiar with, one known  since
the time of the ancient Babylonians, and studied by scientists for more than
two hundred years.

     Under the right conditions, hypnotists can influence people to say  and
do things they wouldn't normally say and do. While in a  hypnotic  state,  a
subject is focused yet highly relaxed and suggestible. He  becomes  detached
from his sense of reality , his critical faculties, and the sensory input of
his own body. His attention is absorbed and directed by the issues raised by
the hypnotist.  The  hypnotist  can  then  make  some  suggestion  that  the
subject-unless he finds it extremely objectionable-will believe  or  follow.
Dr. Michael Yapko, clinical psychologist and  author  of  the  authoritative
hypnosis text Trancework, explains, "If someone is  ambivalent,  riding  the
fence, you can sway them."

     If the stormtrooper and Bib aren't passionate about  their  jobs,  then
they may be able to be swayed. Suggestions can make a  person  behave  in  a
particular way, or see or hear things that don't even exist. A  subject  may
believe a mosquito is buzzing around him. He may stick his hand in a bowl of
ice water and find it pleasantly warm, or he may look at a colorful  drawing
and see it only in shades  of  gray,  as  if  color-blind.  In  response  to
suggestions, he may become paralyzed, amnesic, delusional, or insensitive to
pain. Some people have  even  been  able  to  undergo  childbirth  or  major
surgery, such as an amputation , without feeling pain.

     Observing such abilities actually inspired Dr. Yapko to study hypnosis.
"People have latent strengths and capabilities they aren't aware they have."
Some subjects find behavioral changes,  such  as  quitting  smoking,  weight
loss, or overcoming phobias, easier . These latent  abilities  may  also  be
used for less constructive purposes. Subjects may believe  their  posteriors
have been glued to chairs (I wouldn't mind seeing a platoon of stormtroopers
in that condition). Or they may believe R2-D2 and C-3PO are not  the  droids
they're looking for. Dr. Yapko stresses that  hypnosis  is  merely  a  tool.
"Hypnosis is not a good thing. Hypnosis is not a bad thing.

     It's all in how you apply it." Does that mean hypnosis has a light side
and a dark side?  "Sure,"  he  answers.  Hypnotists  phrase  suggestions  in
certain specific ways. Which type of  suggestion  is  best  depends  on  the
individual. Knowing what kind of suggestion to use, Dr. Yapko says, is  part
of "the artistry of hypnosis." With a direct suggestion, the hypnotist tells
the subject what he wants the subject to believe or do, as in "These  aren't
the droids you're looking for."

     With an indirect suggestion, the the  hypnotist  presents  the  desired
belief or action in a more oblique way, as in "Isn't it a relief to see that
these aren't the droids you're looking for?"  Obi-Wan  and  Luke  both  give
direct suggestions rather than indirect ones. Subjects looking  for  answers
may be  happy  to  adopt  a  direct  suggestion,  while  those  anxious  and
emotionally guarded may respond better to an indirect  suggestion  .  Luke's
suggestion is authoritarian in nature, which as described by Dr.  Yapko  is,
"You will do X," as in "You will take me to Jabba now."

     Obi-Wan's suggestions are not quite  so  forceful,  phrased  in  a  way
almost to make the stormtrooper  relax,  yet  they  too  are  authoritarian,
commanding the stormtrooper to adopt his statements as fact. C. Roy  Hunter,
a hypnotherapy instructor, recommends using present tense  for  suggestions,
as Obi-Wan does. If future tense is used,  he  stresses  the  importance  of
specifying when the action will be done. Luke, in his  above  command,  does
just that. So the suggestions given by Jedi,  and  the  reactions  of  those
under their influence, seem quite similar to those in hypnosis. Yet in  Star
Wars, we don't  actually  see  these  people  being  hypnotized.  Could  the
stormtrooper and Bib be hypnotized so quickly? While most of us think  of  a
hypnotist swinging a watch back and forth, saying, "You are getting sleepy,"
contemporary hypnotists use a variety of methods to induce a hypnotic state.
Most of these work slowly, over perhaps fifteen minutes, gradually deepening
the subject 's relaxation. Yet a rapid technique  is  often  used  by  stage
hypnotists .

     This method, described as a shock  to  the  system,  is  the  one  most
similar to what we see in Star Wars. The hypnotist gives a  sudden  forceful
command in a surprising manner, and puts the subject into a  hypnotic  state
in seconds. Roy Hunter explains, "The participant or client will  experience
a 'moment of passivity' during which  he  or  she  will  either  resist  the
trance, or 'let go' and drop quickly into  hypnosis."  Though  not  loud  or
showy, both Obi- Wan and Luke make forceful assertions that would  certainly
surprise those to whom  they  speak.  Yet  Dr.  Yapko  stresses  that  stage
hypnotists do some preliminary work with subjects  before  they  "instantly"
induce hypnosis. "They administer suggestibility tests to deduce a  person's
level of responsiveness in that situation."

     One test might be telling a person  she  has  a  special  glue  on  her
eyelids, and she won't be able to open her eyes. The  hypnotist  then  tells
her to open her eyes, and if she can't, he knows he has a good  subject  for
his show. Inducing a traditional hypnotic state in a subject who  has  never
been hypnotized before, even with these rapid  methods,  takes  at  least  a
minute or two. So it's unlikely  that  Ben  or  Luke  induce  a  traditional
hypnotic state in their subjects. Yet in  many  cases,  suggestions  can  be
given and accepted without the  subject  being  hypnotized,  just  like  the
suggestion of glue on the eyelids. Some therapists call  these  "nonhypnotic
suggestions," while others prefer to define hypnosis much more  widely.  The
difficulty in establishing exactly when someone is  hypnotized  arises  from
the fact that we still don't have a clear definition of this state. The EEGs
of hypnotized people look much the same as  those  of  people  under  normal
conditions, so we can't definitively say whether someone is  in  a  hypnotic
trance or not.

     Neuropsychologists disagree about exactly  what  is  occurring  in  the
brain during hypnosis. Scientists offer three  general  explanations  .  Dr.
Yapko believes that "there are  elements  of  each  explanation  evident  in
hypnosis." First, some scientists believe the hypnotic state  is  a  unique,
altered state, in which the mind operates in a  different  way  than  usual.
That would explain why hypnosis allows  us  to  access  abilities  we  can't
normally  access.  Others  believe  we  enter   similar   states   of   high
concentration every day, when we daydream or become  engrossed  in  a  great
book or movie, like The Phantom Menace. Still others believe  that  hypnosis
is simply a process in which the  subject  decides  to  cooperate  with  the
hypnotist, imagining various things and acting out various  behaviors  .  In
this  view,  subjects  are  suggestible,  imaginative,  and  intimidated  by
authority figures, whom they don't want to disappoint.

     The second and third explanations allow a wider definition of hypnosis,
allowing hypnotic activity to occur even when someone hasn't  been  formally
hypnotized.  Some  therapists  consider  a  conversation  including   direct
suggestion to be hypnosis.  Dr.  T.  X.  Barber  ,  author  of  Hypnosis:  A
Scientific  Approach,  points  out  that  a  conversation  involving  direct
suggestions to experience, think, and feel particular things  can  stimulate
responses quite similar to those obtained in a traditional  hypnotic  state.
Such suggestions might make a subject  believe  that  his  extended  arm  is
becoming horribly heavy, or that he can't unclasp his hands.

     In one study, about 40 percent of participants  experienced  visual  or
auditory hallucinations when these  were  suggested,  without  any  hypnotic
induction. Dr. Yapko believes that "hypnosis occurs to some degree  whenever
someone turns his or her attention to and focuses on the ideas and  feelings
triggered by the  communications  of  the  guide."  This  condition  can  be
triggered merely by an  offhand  remark.  If  it  influences  the  subject's
experience, then it is hypnotic. Rather than entering a unique state,  then,
the patient is interacting with  the  hypnotist  in  "hypnotic  patterns  of
communication"  that  focus  the  patient's  attention.   For   non-hypnotic
suggestions to work, Dr. Yapko believes a hypnotist requires skilled control
of his voice and body so that they project credibility and authority. In the
authoritarian technique , the hypnotist fixes his  eyes  on  the  subject's.
Both Ben and Luke do this, drawing their subjects' attention to them.  Other
methods may also help focus a subject's attention.

     When Obi-Wan talks to the stormtrooper, he makes a small  gesture  with
his hand. Luke extends a finger toward Bib when he makes his suggestion. Dr.
Yapko points out, "When somebody gestures, it draws attention to them and to
the gesture. It's a good way of securing the person's attention to a greater
extent." More than that, the hypnotist  must  seem  at  all  times  to  know
exactly what he's doing. "Certainty is persuasive. When Steven Seagal  walks
into a room with ten bad guys, and he insults the  man  in  charge,  there's
something intimidating about someone with that  level  of  confidence.  This
makes the bad guys afraid. They think, 'Maybe he knows something I don't.'

     That uncertainty can lead you to be more likely to comply  with  or  be
intimidated by that person whose level  of  certainty  is  so  great."  Both
Obi-Wan and Luke are quite certain in  their  assertions.  Yet  a  hypnotist
needs more than confidence and an authoritative posture and voice. For rapid
induction or non-hypnotic suggestions to succeed, according  to  Dr.  Yapko,
there  must  be  "some  expectation,  some  history,  some   rapport,   some
willingness to accede to an authority." A stage magician may have  authority
from  his  fame.  The  subject  believes  the  magician  has  some  hypnotic
abilities. He expects to be hypnotized, and probably wants to be hypnotized.

     He may have seen demonstrations of hypnosis before, which would provide
a history, and his volunteering reflects a  willingness  to  submit  to  the
hypnotist's authority. A psychotherapist's credentials  and  the  trust  the
subject has placed in him give  him  his  authority.  The  preliminary  work
between the therapist and the subject sets up a rapport between them. In the
case of Luke and Bib, expectations are set up ahead of time  when  Bib  sees
Luke's holographic message, which is projected  by  Artoo.  Luke  identifies
himself as a Jedi knight, and hints that if Jabba doesn't agree to turn over
the frozen Han, an "unpleasant confrontation" may result. Dr. Yapko, a  Star
Wars fan, says, "If the guard knew that Luke was on a par with  Darth  Vader
in terms of using the Force, and that he was under an implied threat  if  he
countered Luke,  that  might  be  enough  to  intimidate  him  or  make  him
susceptible to Luke's influence."  In  this  case,  some  history  and  some
expectation-that  Luke  might  use  that  "old  Jedi  mind  trick"-has  been
established.

     But in the case of Obi-Wan and the stormtrooper,  no  such  history  or
expectation could have been  established.  While  the  result  of  Obi-Wan's
suggestions is similar to that in hypnosis, it seems he  must  be  taking  a
shortcut to get this effect. His mind appears able to  directly  affect  the
minds of others, as we discussed in connection with  quantum  mechanics.  We
have another example of the Force's influence, though, that  does  not  seem
hypnotic at all. A hypnotist works by making  verbal  suggestions  that  the
subject then accepts. While we might argue that Obi-Wan works this way  with
the stormtrooper he encounters on Tatooine, he doesn't  even  speak  to  the
stormtroopers on the Death Star. After deactivating  the  tractor  beam,  he
needs to make the stormtroopers look the other way to get past them. With  a
small gesture of his hand, he somehow makes the stormtroopers  believe  they
have heard a sound down the hallway, which makes them look away.

     No process we can recognize as hypnosis is occurring here. It seems  as
if Obi-Wan is  either  telepathically  affecting  their  minds,  planting  a
suggestion there, or else that he has created an actual sound down the  hall
by the manipulation of matter and energy. As Dr. Yapko says, "It must be the
Force."



     MEASURING THE FORCE IN THE LAB?


     Since the hypnotic state is  not  easily  definable,  researchers  have
focused on other paranormal phenomena to find concrete evidence  of  psychic
powers. Phenomena such as telepathy, clairvoyance,  and  psychokinesis  have
been the subjects of  extensive  parapsychological  research.  We  discussed
earlier whether the Force might be theoretically possible. Yet theory  isn't
the only issue involved in exploring the  Force.  Science  seldom  works  by
creating a theory and then discovering  evidence  of  it.  Usually,  science
works by observing an unexplained phenomenon and then creating a theory that
can describe or  explain  it.  Gravity  existed  before  we  understood  its
workings-even  now  we  don't  entirely  understand  it-and  the   phenomena
associated with the Force may exist, whether or not we can explain how  they
might theoretically operate. Dr. Jessica Utts, professor  of  statistics  at
the  University  of  California  at  Davis  and  researcher  of   paranormal
phenomena, says, "There are a lot of things we accept scientifically  before
we know how they work. Consider learning and memory.  Psychologists  do  not
understand these simple human  capabilities,  yet  no  one  would  deny  the
existence of these phenomena just because we do not understand them."

     Since the establishment  of  the  Society  for  Psychical  Research  in
England in 1882, scientists have been engaged in empirical research  to  see
if they can document paranormal phenomena. Many believe that they have. They
have  different  ideas,  though,  about  how  these  phenomena   relate   to
traditional science. Some parapsychologists believe that these phenomena may
be compatible with our current understanding of the universe. They point  to
quantum mechanics as a possible source of explanations.

     Since quantum theory deals in statistical probabilities, and paranormal
phenomena -as we  will  discuss-also  appear  statistical  in  nature,  they
believe the paranormal is caused by  quantum  effects.  Others  believe  the
proof of these phenomena will require a complete revolution in  science,  in
which we throw  out  everything  we  know  about  physics.  Dr.  Ray  Hyman,
professor  emeritus  of  psychology  at  the  University   of   Oregon   and
self-proclaimed skeptic,  believes  that  "Neither  relativity  nor  quantum
theory can cope with a world that harbors the psychic phenomena."

     Yet others believe these phenomena are truly supernatural and can never
be explained by science . But whether they can ultimately  be  explained  or
not, has convincing  evidence  of  paranormal  phenomena  been  found?  Many
scientists believe their experiments have yielded proof of such powers.  Yet
the scientific community at  large  does  not  believe  conclusive  evidence
exists. Extraordinary claims,  they  say,  require  extraordinary  evidence,
while the evidence of paranormal phenomena  remains  plagued  by  flaws  and
skepticism. Part of this failure is due to faulty  experimental  procedures.
Experiments designed to detect paranormal phenomena seem particularly  prone
to cheating subjects or experimenter fraud. Many scientists have been  taken
in  by  magicians  and   charlatans   whose   techniques   of   fooling   an
audience-including  hidden  radios-are  far  more  sophisticated  than   the
scientists know.

     Magician James Randi, known as The  Amazing  Randi,  has  made  it  his
mission in life to uncover such  charlatans  and  to  reveal  weaknesses  in
paranormal research. He  does  this  through  the  James  Randi  Educational
Foundation of  Fort  Lauderdale.  As  someone  who  has  made  a  living  by
simulating acts of magic, Randi believes  the  simulation  of  magic  should
never be mistaken for or misrepresented as real magic. Dr. Hyman relates one
instance when he himself was fooled. The government asked him to  look  into
the work of a scientist investigating a woman who could allegedly read books
just by running her fingertips over the pages. "She seemed  a  very  ethical
person .

     The woman didn't want any publicity. She didn't even want to be tested.
I knew something was wrong, but I didn't believe any fakery was going on. It
turned out she was cheating  this  scientist  blind."  Randi  believes  many
scientists are too accepting of any evidence that validates  their  beliefs,
which makes them vulnerable to deception by others and even  by  themselves.
"I can go into a lab and fool the rear ends off any  group  of  scientists."
Even if all parties are honest, a desire to  believe  on  the  part  of  the
scientists can allow design flaws to creep into experiments.

     If an experiment is not designed very carefully, scientists may  convey
subtle, unconscious cues to their subjects  that  tell  them  the  "correct"
answer to give to  prove  their  psychic  abilities.  Once  scientists  have
collected data,  they  may  manipulate  it  in  different  ways  to  find  a
statistically significant result. And  if  they  can't  find  a  significant
result, parapsychologists tend not to report their experiments  ,  reporting
only those that yield positive indications of  paranormal  phenomena.  Since
the vast majority of scientists who perform paranormal  research  are  those
who believe in paranormal phenomena, this  problem  is  hard  to  avoid.  In
addition to these problems, parapsychology differs from other sciences in  a
number of ways that make  scientists  from  other  disciplines  hesitant  to
accept potentially positive results. Most scientific disciplines have  basic
experiments that can be easily replicated and produce consistent results.

     These are the experiments your teachers always made you do  in  science
class. Dr. Hyman cites an example. "Isaac Newton did experiments with prisms
to show that light can be separated into  colors.  We  can  still  do  those
experiments and get those results. Every field of science  has  hundreds  of
these textbook-type experiments, which  students  can  do  with  predictable
results. There isn't one experiment in parapsychology like that at all." Dr.
Utts explains why. "I can name other phenomena for which students could  not
be expected to do a simple experiment and observe  a  result,  such  as  the
connection between smoking and  getting  lung  cancer.  What  differentiates
these phenomena from simple experiments like splitting light with a prism is
that the effects are statistical in nature and are  not  expected  to  occur
every single time. Not everyone who smokes gets  lung  cancer,  but  we  can
predict the proportion who will.

     Not everyone who attempts telepathy will be successful, but I think  we
can predict the proportion will." Another difference between  parapsychology
and other fields is that paranormal phenomena can't be disproven. In a field
like physics, experiments are set up so that the results either  support  or
disprove a theory. If the results disprove the theory, then  the  theory  is
discarded. But if a parapsychological experiment fails to show results,  Dr.
Hyman says, the  experimenters  will  argue  that  "the  conditions  weren't
conducive to psychic phenomena."

     Since the workings of such phenomena are wholly  unknown,  the  factors
that may affect them are unclear. All these issues end up  making  belief  a
critical component in how you view  the  experimental  results.  When  these
experiments are reviewed by other scientists, those who already  believe  in
psychic phenomena will find the evidence conclusive, while those  who  don't
believe in psychic phenomena won't. Marc Millis believes  the  only  way  to
approach the data is with an open mind, but  he  explains,  "Open-mindedness
goes two ways. You have to be open- minded to the possibilities that  things
might work, and open- minded to the  possibilities  that  things  might  not
work.

     A lot of people are only open-minded one way." What conclusions are  we
to draw from such research? Many  scientists  believe  that  any  experiment
showing positive indications of psychic phenomena must be flawed, since such
phenomena  are  impossible.  Dr.  Puthoff  feels  "Many  skeptics  are  true
believers in the impossibility of it. They reject the results  because  they
just  can't  imagine  how  it  could  work.  That  level  of  skepticism  is
essentially worthless."

     Others, who have attempted to be open minded as  Millis  suggests,  are
discouraged by the lack of convincing evidence . Yet some  parapsychologists
believe that experiments have proven that paranormal phenomena exist  beyond
any doubt. Dr. Utts asserts that the skeptics have been  unable  to  explain
away  significant  results.  "And  it's  not  for  lack  of   trying."   And
occasionally a physicist, or an engineer, will be converted by a  compelling
piece of evidence or a particular study and  begin  to  research  paranormal
phenomena. Yet  believers  find  their  evidence  is  not  widely  accepted.
"Parapsychologists are the Rodney Dangerfields of science ,"

     Dr. Hyman says. "They want to get respect. Some of the disrespect  they
get is not earned, and some is."  From  their  view,  parapsychologists  are
struggling with meager financial resources to capture magic in the lab.  The
effects of psychic phenomena are so small, Dr. Utts admits,  that  it  takes
hundreds or thousands of trials to measure a significant  result.  Also,  if
subjects are  not  completely  at  ease,  parapsychologists  believe,  their
psychic abilities might be driven away. That's why so  many  psychics,  when
brought into the lab, fail to produce results. If too many controls are  put
on them, they'll feel distrusted.

     And  indeed,  over  the  history  of  parapsychological  research,   as
experimental designs are improved and controls are  tightened,  any  psychic
ability measured keeps getting smaller and smaller. While cynics  feel  this
indicates the actual ability is zero,  believers  feel  additional  controls
kill the subject's spirit. The presence of disbelievers may also  inhibit  a
subject's psychic powers, which is one reason  that  successful  experiments
reproduced by skeptics often don't generate positive results. Just  as  Yoda
tells Luke he must believe for the Force  to  work,  parapsychologists  feel
belief is an important component in their experiments.

     Now that you know some of the factors  involved  in  psychic  research,
let's take a look at some of the results. Then you can decide  for  yourself
whether or not the Force is with us.



     REACH OUT AND TOUCH SOMEONE


     Near the end of The Empire Strikes Back,  Luke  is  hanging  from  what
looks like an antenna on the underside of Cloud City. Using the Force,  Luke
calls out with his mind to Leia for help. She "hears" his  call  and  brings
the Millennium Falcon to his rescue.  As  the  Falcon,  now  carrying  Luke,
attempts to make the jump to hyperspace, Darth Vader calls out  mentally  to
Luke via the Force. Unfortunately, you can't "hang up" on a call carried  by
the Force. Here the Force allows telepathic communication between  people  .
Parapsychologists like to call telepathy "anomalous  information  transfer,"
since information passes from one person to  another  without  any  apparent
means. Have they found any evidence  that  we  might  be  able  to  mentally
communicate with each other?

     The most interesting results have come from  a  series  of  experiments
begun by Dr. Charles Honorton and then continued after his death a few years
ago by Dr. Robert Morris at  the  University  of  Edinburgh,  and  by  other
scientists at a variety of institutions. Dr. Honorton designed a  test  that
he hoped would detect telepathic communication and that  would  be  free  of
design flaws or opportunities for cheating or fraud. Most  scientists  agree
that, if people do have telepathic powers, they must be very weak  for  most
people under most circumstances.

     So Dr. Honorton figured that to  foster  telepathic  communication,  he
needed to free his subjects from all distractions  and  put  them  into  the
ideal  state  to  "receive"  communications.  Alleged  cases  of  telepathic
communication in the  past  have  often  been  associated  with  meditation,
dreaming, or altered states, which is consistent with what we  see  in  Star
Wars. Hanging from the underside of Cloud City, Luke goes into a  meditative
state to call out  to  Leia.  Some  experiments  have  tested  subjects  for
telepathic abilities after either  listening  to  a  relaxation  tape  or  a
tension-inducing tape. Those who were relaxed performed  better  than  those
who were tense.

     In another experiment , subjects tested stronger  for  telepathy  after
meditating. To make his subjects as receptive as possible, Dr. Honorton  put
them into a sensory deprivation chamber. They lay on a reclining chair, with
half a Ping-Pong ball strapped over each eye. A  red  floodlight  created  a
hazy visual field (called a Ganzfeld by German psychologists) and headphones
hissed white noise into their ears. In this fog without  any  sharp  sensory
boundaries, subjects  entered  a  pleasant,  altered  state  within  fifteen
minutes. Then Dr. Honorton chose "senders" that were friends or relatives of
the subject-to increase the chance of a psychic connection -and put them  in
a separate, isolated, soundproof and radioproof room. The sender looked at a
video clip randomly selected by a computer and  attempted  to  transmit  the
image telepathically to the subject.

     The subject gave a running monologue describing any images or  thoughts
coming to mind. After the subject came out of  the  isolation  chamber,  Dr.
Honor- ton or another researcher would show him four video  clips,  and  ask
him to choose which one most closely  matched  his  thoughts  while  in  the
isolation chamber. The experimenters did not know which image was  shown  to
the sender, so they could not  bias  the  results  in  any  way.  Since  the
subjects were shown only four clips, they should have picked the image shown
to the sender simply by chance 25 percent of the time, without any telepathy
operating. Yet Dr. Hon- orton's tests showed that  the  subject  picked  the
correct image 35 percent of the time, much more than could be  explained  by
chance.

     And the most recent tests run at the University of Edinburgh found  the
subjects picked the correct image nearly 50 percent of the time.  Are  these
subjects actually receiving telepathic images?

     While skeptical scientists have yet to definitively prove  the  results
invalid,  they  have  identified  several  possible  design  flaws  in   the
experiment that might lead to misleading results. Remember as you read these
that this experiment, like all paranormal research , is set up to measure  a
statistical effect, not an absolute one. Gravity will make a book fall every
time I drop it, but telepathy  will  not  allow  communication  between  two
people every time they try it-at least not on this  planet.  The  experiment
shows that subjects pick the correct clip more often than would be  expected
by chance. So any factors that might affect the chances of a subject picking
a certain clip are relevant. One possibility, unintentional correlations may
be playing a role in the results. For example, people  hearing  white  noise
tend to think about water more often than sex (set your radio to the  static
in between two stations and test it!).

     If the video images selected by the computer happen to be  of  a  tidal
wave more often than of two people in bed, and subjects more often  identify
the image of the wave rather than the image  of  the  people  in  bed,  this
doesn't  mean  any  telepathic  communication  has  occurred.  This   simply
indicates that a subject listening to  white  noise  is  often  reminded  of
water. This was the case in one such  experiment.  Another  possibility,  of
four images shown to them, subjects tend to choose either the first or last.
If the images selected by the computer happen to be  shown  to  the  subject
first or last more often than in the middle two positions, the subject might
choose them with no telepathy involved. This was a factor  in  a  number  of
experiments.

     If a video clip is played over and  over  as  the  sender  attempts  to
transmit the image, the clip might become staticky and degraded .  When  the
clips are played for the subject, then, he could guess which clip  had  been
used. Another potential danger, researchers may have known which  image  the
computer selected, even though they weren't supposed to. The researchers may
have purposely gotten this information, by looking at the counter on the VCR
holding the video clips, or they may have subconsciously known  it,  by  the
amount of time it took the  VCR  to  rewind  after  showing  the  clip.  The
researcher might then subtly influence the subject to  choose  a  particular
image over the others.

     In fact, the researcher often spoke to the subject during the selection
process, pointing out different elements in the clips and relating  them  to
what the subject said while in isolation.  Dr.  Hyman  questions,  "Are  you
measuring the ability of the subject to pick out the right  target,  or  the
ability of the researcher?" In  the  experiments  yielding  the  50  percent
success rate, most of the successful hits came from trials involving one  of
three researchers, suggesting the researcher was influencing the results. So
the Ganzfeld evidence remains controversial.

     You might think that these flaws seem rather small  and  unlikely.  The
key issue is whether the flaws identified  could  account  for  the  results
observed. In his study of Ganzfeld results, Dr. Hyman says, "At first I  was
pretty impressed. But as I kept going through them, I found there  wasn't  a
single experiment in the database of forty- two experiments  that  was  free
from obvious flaws." Dr. Utts believes, though, that "if all the experiments
have different weaknesses but all come up with the same magnitude  of  fact,
that's pretty convincing." As a physicist and  a  perfectionist,  though,  I
can't help feeling uncomfortable accepting flaws in experiments.

     Whether these flaws can completely account for the  effect  observed  ,
though, remains unclear. What tends to convince most believers  is  not  the
statistics, but isolated, striking cases that  appear  to  be  instances  of
telepathic communication. In one experimental trial, for example, the  video
clip used was a scene from the movie Altered States. The scene, in shades of
red, depicted a hellish hallucination comprised of a jumble of images: a man
screaming, people in fire and smoke, a sun with a corona around it,  a  mass
crucifixion, people jumping off a precipice, lava and smoke,  and  a  lizard
opening its mouth. Here's what the subject in the Ganzfeld said: "I just see
a big X. A big X. I see a tunnel in front of me. It's like a tunnel of  smog
or a tunnel of smoke. I'm going down it. I'm going down it at a pretty  fast
speed.... I still see the color red, red, red, red, red,  red,  red....  Ah,
suddenly the sun... the kind of cartoon sun you see when you  can  see  each
pointy spike around the sphere.... I stepped on a piece of glass and there's
a bit of blood coming out of my foot.... A  lizard  with  a  big,  big,  big
head."

     The correspondences are quite compelling. Yet this is  only  one  trial
out of many. And  the  complex  video  clip  offers  such  a  hodgepodge  of
different images that it seems a subject might stumble into a couple of them
by accident. From a scientific perspective, the  relevant  evidence  is  not
what the subject said, but whether the subject chose the correct clip at the
end (which she did). To be convinced by isolated trials, though,  scientists
must ignore many, many other trials that show no correspondences. While most
scientists believe these isolated trials are mere flukes,  parapsychologists
assert they are examples of a gifted subject caught at a favorable time.

     I had my own close encounter with telepathy while writing this book. At
the end of my interview with The Amazing Randi, I asked the magician  if  he
could read my mind. He astutely said, "You're thinking it's about time to go
and I've been very patient with  you."  Who  is  the  most  likely  to  have
telepathic  abilities?  According  to  parapsychologists,  those  who  score
highest believe in telepathy and have training in meditation, relaxation, or
creativity. A small group of  students  at  the  Juilliard  School  for  the
performing arts had the highest rate  of  matches  of  a  single  group,  50
percent.  Since  Yoda's  training  incorporates  belief,   meditation,   and
relaxation, he may be increasing the telepathic ability of his students.  He
may want to throw in some creativity  training-perhaps  a  finger  -painting
class?



     THE FORCE LIES NOT IN OURSELVES, BUT IN THE STARS?


     Parapsychologists do some truly bizarre experiments in their  quest  to
find and understand psychic phenomena, and here's one.  Dr.  James  SPottis-
woode of the Cognitive Sciences Laboratory in Palo Alto  wondered  if  there
might be a correlation between psychic ability and an Earth-bound  subject's
orientation with respect to the  stars.  Such  orientation  is  measured  by
astronomers in sidereal time, or star time. What  he  found  was  that  both
telepathic and clairvoyant abilities more than tripled when  local  sidereal
time was near 13:30. This result, according to Dr. Spottiswoode, suggests an
object in the sky has some effect on telepathic abilities, perhaps  by  some
signal it emits.



     PEEPING JED]


     Yoda tells Luke that through the Force he can "see" events occurring at
a great distance, or events in the past or future. Yoda  himself  admits  to
"watching" Luke for a long time. Might we call him a peeping Jedi?

     Traditionally this ability to see distant  locations  and  actions  has
been known as clairvoyance, yet scientists again have come up with their own
name: remote viewing. The Pentagon's  Defense  Intelligence  Agency  shocked
scientists when it revealed, three years ago, that it  had  been  conducting
research on remote viewing for the past twenty years.  The  results,  as  we
might expect, were controversial. The remote-viewing experiments were set up
in several different ways.  In  one,  five  sites  in  the  surrounding  San
Francisco Bay area were selected. A researcher chose one of these sites  and
traveled to it, serving as a "beacon" to draw the subject's attention to the
spot.

     In a sealed room, the subject sat with another researcher, waiting  for
word that the "beacon" had arrived at the site. After  receiving  word,  the
subject  attempted  to  describe  and  draw  the  site.  His  comments  were
tape-recorded and later transcribed.  The  subjects  were  discouraged  from
naming objects, such as saying "I see Jabba's  palace."  Instead  they  were
encouraged to simply describe or draw shapes. This  technique  brought  more
successful results ,  which  researchers  explained  with  the  belief  that
psychic talents do not involve the  verbal  part  of  the  brain.  Dr.  Utts
explains , "What seems to come through are more general  images  and  shapes
than high-level interpretation."

     In other trials, the subjects were given coordinates of  longitude  and
latitude and asked to draw what was there, without a "beacon ." The  results
were the same with or without a  beacon,  which  brings  into  question  how
remote viewing works. With a  beacon,  remote  viewing  might  not  be  much
different than telepathy, the beacon sending information to the subject. But
with no beacon, the subject seems to be somehow traveling  mentally  to  the
site and observing it. The remote viewer seems equally successful  at  short
and long distances, and even sometimes sees into the past or future  .  Some
researchers, including Dr.  Utts,  actually  believe  remote  viewing  works
through precognition. Since the subject is taken to the  actual  site  after
the trial, the subject's earlier  description  may  have  been  obtained  by
looking into the future to see it.

     Once all five sites had been "remote viewed," the number of  successful
matches had to be evaluated. The director of the study tried  to  match  the
subject's drawings and descriptions  to  five  different  sites.  Simply  by
chance, the director would be expected to make correct matches 20 percent of
the time. Similar to the Ganzfeld experiments, the results were higher  than
could be explained by chance. After twenty years of study, the CIA hired two
researchers to  evaluate  the  evidence  collected.  One,  Dr.  Utts,  found
convincing and conclusive evidence of remote-viewing ability in some of  the
subjects. The other, Dr. Hyman, did not find the evidence convincing .

     Dr. Puthoff, who was the founder of the research program, says that Dr.
Hyman "admitted that the data were statistically significant.  But  he  said
there must be flaws, even though he wasn't able to find what they were." Dr.
Hyman, though, explains that while the experiments  seemed  better  designed
than previous ones, they introduced some new  procedures  that  hadn't  been
tried before . "Every time new procedures are introduced, it takes  time  to
find the bugs in them.

     There are always flaws in every experiment ." The  CIA  concluded  that
the study provided insufficient evidence and no scientific grounds  for  its
claims, and stopped funding the research. Perhaps we can  identify  some  of
the possible flaws in the remote -viewing research by looking at  a  similar
experiment. Drs. David Marks and Richard Kammann at the University of  Otago
in New  Zealand,  authors  of  The  Psychology  of  the  Psychic,  tell  the
fascinating story of their attempt to reproduce the  remote-viewing  results
of the government researchers. They followed the same  procedures  and  were
quite surprised and disappointed to find that they obtained  no  significant
results. All of their subjects failed miserably as remote viewers.  The  odd
thing was, almost invariably, when the subject and the  beacon  visited  the
site after the trial, they would be convinced that the subject had described
the site accurately.

     They would see strong correspondences between the subject's description
and various elements of the site, just as we saw correspondences between the
scene from Altered States and the Ganzfeld subject's description . But  when
a judge completely unconnected with the experiments would try to  match  the
transcripts and drawings with the  list  of  sites,  the  judge  would  draw
different successfully viewed the sites, but  he  would  connect  the  wrong
transcript to the wrong site. For example, one site might be  a  house.  The
subject and researcher might visit the house and find that the view  looking
away from the house toward the street matches some of the  elements  in  the
transcript corresponding to this site.

     The judge might instead find the view looking toward the house  matches
some of the elements of another transcript. Drs. Marks and Kammann call this
phenomenon  "subjective  validation,"  which  they  say  occurs  "when   two
unrelated events are perceived to be related because a  belief,  expectancy,
or hypothesis demands or requires a relationship ." If  someone  believes  a
transcript accurately describes a site, and he "visits a location with  that
description  fresh  in  his  mind^any   description-he   will   easily   and
effortlessly find that the description will match."

     In other words, "Any description can be  made  to  match  any  target."
Since subjects were discouraged from specifically naming objects, this  only
made the transcripts easier to interpret in different ways. If that  is  so,
though, how did the original researchers obtain better-than-chance levels of
matching? What allowed their judge to match the correct  transcript  to  the
correct site so many times? Well, Drs. Marks  and  Kammann  found  that  the
judge in the government experiments was given a list of  the  sites  in  the
exact order they were used. This wouldn't matter, unless the judge also knew
the order in which the transcripts and drawings were generated. If  he  did,
then simply matching the first site with the first transcript,  and  so  on,
would be easy enough.

     But did he know? In examining five transcripts of subject Pat Price,  a
star in the government remote-viewing experiments, Drs. Marks and Kam-  mann
found that each transcript contained cues about the order in which they  had
been recorded. For example, in one transcript Price expresses anxiety  about
his ability to remote view, from which one might conclude that this  is  his
first attempt. In his second viewing, he mentions this is the "second  place
of the day," and in his third he mentions "yesterday's two targets." In  his
fourth, the experimenter says, "Nothing like having three  successes  behind
you." In his fifth, Price refers to the marina that was site  number  4.  If
the judge knew in which order the sites had been visited,  he  could  easily
match the transcripts to the sites with 100 percent  accuracy,  which  Marks
and Kammann did.

     The specific description given in the transcript and whether it matched
the site would be completely irrelevant. In other less dramatic  cases,  the
judge could at least re-create a partial chronological order, increasing the
chance of a correct match. Some transcripts even had dates  on  them!  Marks
and Kam- mann were unsuccessful in generating a high number  of  matches  in
their experiment because they edited such cues out of the transcripts before
the judges saw them. Dr. Puthoff  disputes  the  claim  that  matches  arose
because of cues in the transcripts. "To address these criticisms, we  turned
over the entire experiment to an independent third party. He edited out  all
the cues and arranged to have the transcripts judged again. The  judge  made
the same matches as originally found in our study, proving  that  the  Marks
and Kammann cue hypothesis was false." Dr. Puthoff  stresses  that  accurate
descriptions of the targets generated the matches, not the cues.

     In examining the transcripts of the government tests, Marks and Kammann
found another possible cause for the positive results . They claim that some
experimental  trials  were  conducted  and  not  reported,  suggesting   the
government experimenters selected the most promising results to  report  and
discarded others. The work of Marks and Kammann  may  help  to  explain  how
higher-than-chance  matching  occurred.  But  researchers  again  point   to
isolated cases that appear to offer compelling evidence of  remote  viewing.
One subject, the same one whose  transcripts  were  studied  for  cues,  was
particularly  successful.  This  subject,  Pat  Price,   a   former   police
commissioner, claimed that he would listen to  calls  on  the  police  radio
reporting crimes, psychically scan the city, and then send a police unit  to
the place where he saw a frightened man hiding.

     In one remote-viewing trial, Price described a site,  a  swimming  pool
complex, in great detail. All the details were accurate except for  one:  he
described water storage tanks at the  complex  and  there  were  none.  Much
later, researchers discovered that such tanks had existed in  that  location
in 1913, and so they cite this as a powerful example of  remote  viewing  of
the past. While this may be so, it seems to me that if you consider what has
been at any site through the entire course of history,  you  could  probably
find something to match Price's drawing. In another  experiment,  Price  was
asked to remote  view  a  Russian  research  and  development  facility  ten
thousand miles away.

     Price drew a crane and a section of a giant metal sphere. Only  several
years later did the experimenters learn that these actually existed  at  the
site. Yet Price drew many other things that he "viewed"  at  the  site,  and
these were not found there. Another remote  viewer,  Ingo  Swann-called  Obi
Swann by some of the  researchers-decided  to  remote  view  Jupiter  before
NASA's Pioneer 10 flyby. Swann,  a  career  psychic,  "saw"  a  ring  around
Jupiter before the ring was discovered. In addition to the experiments we've
discussed, the Pentagon has regularly consulted  remote-viewing  "spies"  to
gather intelligence . Such remote viewers  have  drawn  pictures  of  secret
Soviet submarine construction sites, North Korean  tunnels,  and  the  house
where American general James Dozier was held while kidnapped in Italy. Their
descriptions and drawings, when compared with reconnaissance photos or other
data, are claimed to be accurate 15 to 20 percent of the time.

     How could such success rates be obtained,  if  remote  viewing  is  not
possible? Magician James Randi provided a fascinating example as we spoke on
the phone one day. I was in New Hampshire, Randi in Florida. Randi  said  he
would "remote view" something that I drew. He asked me to  draw  two  simple
geometric shapes, one inside the other. I grabbed a pen and quickly drew the
two shapes. (If you'd like to play along, stop reading now and draw your own
two shapes. Ready?) He then asked if I'd drawn a triangle within a circle. I
was amazed. That was exactly what I'd drawn! (How about you?) I asked how he
had guessed that.

     He answered, "This is one of the tricks of  the  trade.  We  know  what
people are likely to draw under certain circumstances."  Most  people,  when
asked to draw one geometrical shape inside another, draw what I  drew.  That
explains some of the positive results, but how might a drawing by a  "remote
viewer" agree with reconnaissance photographs of  an  area  the  viewer  has
never seen? The key, Randi tells me, lies in drawing a  very  general  shape
that can be interpreted in many different ways. If the researcher  wants  to
see a correlation between the drawing  and  the  reconnaissance  photograph,
then he will find one, just as Marks and Kammann described with  "subjective
validation." As an example, Randi says to draw a narrow, horizontal ellipse,
like a worm crawling across your paper. Then from each  of  the  two  narrow
ends of the ellipse, draw a slanting line  upward  so  that  the  two  lines
intersect and form an inverted V above the ellipse. This one drawing,  Randi
points out, could be interpreted in a number of ways: as an ice cream  cone,
an old- fashioned cup from a vending  machine,  a  searchlight,  a  tent,  a
sailboat, a horn, a party hat, and many more.

     As Randi says, "It's  close  enough  for  government  work."  Do  these
explanations account for all  the  positive  results  found?  As  with  much
paranormal research, it's hard to say. And in the case  of  remote  viewing,
much of the research remains classified . Both Dr. Utts and Dr. Hyman  agree
that more investigation is warranted, though the government seems  unwilling
to continue funding the research. Yet Randi's foundation offers a reward  of
$1.4 million to any remote viewer who can tell  Randi  what  he  has  sealed
within a specific cupboard in his Fort Lauderdale home.

     The cupboard holds a simple household object, such as an  orange  or  a
bottle of ketchup-changed every few weeks for security purposes. No one  has
met this challenge. Those who claim to be remote viewers, says Randi,  "make
all sorts of excuses. They would rather view Lebanon or  Jupiter  than  Fort
Lauderdale, because they can fool their clients into believing that they are
correct, but they can't fool me." This  reward  is  not  only  available  to
remote viewers, but to anyone who can  exhibit  a  true  paranormal  ability
under controlled conditions. If you're feeling the Force and want to try for
the reward , you can get more details on Randi's website,  which  is  listed
under "Recommended Reading" at the end of this book.



     THE REVENGE OF THE SCIENTISTS


     In the introduction to this book, I said that my  purpose  was  not  to
nitpick. But I thought I'd give a few scientists this one  chance  to  share
the Star Wars science goofs that most got their goats. Marc  Millis,  leader
of the breakthrough propulsion physics program at NASA: "If you can pick  up
an object and hurl it at Luke Skywalker, why not just hurl  Luke  Skywalker?
Why not bend the light saber out of the way as it's coming at you? Obviously
there's a limit as to how  well  this  thing  works."  Dr.  Victor  Stenger,
professor of physics at the University of Hawaii: This business  where  they
travel great distances instantaneously. I don't buy it.  I  think  wormholes
exist, but I don't think people will ever be able to go down there  and  end
up in another part of the universe in any controlled way.

     Maybe particles can do that, but a whole composite object would be torn
apart. Dr. Miguel Alcubierre, a researcher at the Max Planck  Institute  for
Gravitational Physics in Pottsdam, Germany:  "The  sound  of  explosions  in
space. That bothers me most. Something blows up, and you hear a big ka-boom!
Explosions would never make a sound. Being a science fiction fan on the  one
hand and a physicist on  the  other,  there's  a  duality.  You  know  as  a
physicist that most of the things that you like as a fan can't be done.  You
have to turn off your brain. Sometimes you're just  annoyed  that  something
you know we can do, they do completely wrong."

     Dr. Clifford Pickover, biochemist and author of The Science of  Aliens:
"The various alien musicians in the Max Rebo Band seem to  appreciate  music
exactly in our audio spectrum. It seems unlikely that music would evolve  so
similarly." Mark Stafford, engineer, State of Alaska Division  of  Emergency
Services: "The fighters in the movies bank when they turn, but airplanes  do
that because the airfoils that give them lift make them tilt when they turn.
Ships in space should just turn on an even line. And why didn't  Grand  Moff
Tarkin just blow Yavin up at the end of A New Hope, instead  of  taking  the
time to go around it? Blowing up Yavin would almost  certainly  destroy  all
its moons."

     Dr.  Jessica  Utts,  professor  of  statistics  at  the  University  of
California at Davis: "This isn't a goof, but Obi-Wan  Kenobi's  name  has  a
play on words. Obi is pronounced the some as  OBE,  out-of-body  experience.
It's a little message that it is possible that one can have an  OBE."  Steve
Grand, director of the Cyberlife Institute: "I try never to  let  scientific
implausibility get in the way of a good story!  Ordinary  terrestrial  movie
plots are implausible enough, so why complain about goofs in Sci-Fi?"



     A JED] PICK-ME-UP


     The Force allows a Jedi to move objects  just  by  thinking  about  it.
Darth Vader uses this ability in his light saber duel  with  Luke,  mentally
tossing pieces of equipment at him; Yoda even raises Luke's  X-wing  fighter
out of the swamps of Dagobah. People have claimed to  perform  similar  acts
here on Earth. The ability to move objects without any known physical  means
is  called  psychokinesis.  As  with  both  telepathy  and  remote  viewing,
psychokinetic power is  believed  to  be  rare  and  small.  In  fact,  most
parapsychologists feel psychokinesis is  probably  limited  to  the  quantum
level. So lifting an X-wing seems unlikely at this point. The most promising
results come from Dr. Robert Jahn's experiments , conducted at the Princeton
Engineering Anomalies Research Laboratory. Dr. Jahn, the former dean of  the
School of Engineering and Applied Science at  Princeton  University,  became
interested in psychokinesis when a senior student's project seemed  to  find
evidence of it on the quantum  level.  Intrigued  by  the  possibility  that
consciousness might be "creating reality" on this level, Dr.  Jahn  followed
up with experiments of his own.

     Many of these experiments involve  a  random  number  generator  (RNG),
which we discussed earlier. In this case, the possible numbers  are  limited
to ones and zeroes, so that the RNG performs the  electronic  equivalent  of
tossing a coin, with a 50 percent chance of  a  "heads"  outcome  and  a  50
percent chance of "tails." The generator can perform  200  coin  tosses  per
second, a  speed  that  allows  Dr.  Jahn  to  collect  massive  amounts  of
experimental data. Dr. Jahn has a participant sit in front of the  generator
and try to influence the outcome, trying to make the RNG produce either more
heads or more tails. If the subject has no  effect,  then  the  sequence  of
heads and tails should be random and each should appear 50  percent  of  the
time. When Dr. Jahn averages the results of many trials,  he  finds  a  very
small effect, yet one he claims is statistically significant.

     In one typical  series  of  experiments,  when  participants  tried  to
generate more heads in the 200 tosses,  the  average  number  of  heads  was
100.037, while the number of tails was 99.966. Thus  when  subjects  want  a
flip to come up heads, the chances  of  it  turning  up  heads  are  not  50
percent, as we would believe, but 50.02 percent. In every 1,250 flips, heads
will come up one extra time. This may sound like a tiny, tiny effect, and it
is. Certainly if you flip a coin two times, you won't always  get  one  head
and one tail. You could easily get 100 percent heads and  O  percent  tails,
and we wouldn't need psychokinesis to explain that. If you flip  a  coin  20
times, you won't always get 10 heads and 10 tails. Yet  with  20  flips,  we
would consider it quite odd if you flipped  100  percent  heads.  With  this
larger number of trials, such a huge deviation from chance is very unlikely.

     If you flip a coin 200 times, you won't always get 100  heads  and  100
tails. Yet we'd now consider it completely spooky if you flipped 100 percent
heads.

     We'd have to check you for demonic possession-but that's another  book.
The result of all this is that the larger the number of flips,  the  smaller
any deviation from chance should be. Since  any  deviations  should  average
themselves out over the long haul, large numbers of  flips  should  generate
results very very close to 50-50. Over the past twelve years, Dr.  Jahn  has
tested 91 different subjects in 1.7 million  trials,  for  a  total  of  340
million coin tosses. At that level, having subjects flip 50.02 percent heads
is a significant deviation from chance. The possibility of such  an  outcome
occurring by chance is one in 2,500. Dr.  Jahn  believes  this  proves  that
people have the ability to affect sensitive electronic components with their
minds.

     To see if people could affect larger-scale objects, he  built  a  large
"random mechanical cascade," which looks like a  cross  between  a  carnival
game and a pinball machine. Nine thousand polystyrene balls, about half  the
size  of  Ping-Pong  balls,  are  dropped  down  through  the  ten-foot-high
six-foot-wide cascade, which has 330 pegs that send the  balls  bouncing  in
random directions. At the bottom of the cascade is a row of  nineteen  bins.
Usually most balls land in the center bins and fewer in the outer bins,  the
heights of the stacks of balls forming a bell-shaped curve.

     Dr. Jahn has participants try to influence  the  paths  of  the  balls,
making more go to the bins either on the left or the  right.  He  has  found
that participants are able to make more balls land to the left,  though  not
to the right, for some reason he has yet to understand. The  possibility  of
the measured results occurring by chance is just one in  33,000.  Just  like
the other paranormal phenomena, psychokinesis seems to violate everything we
know about  physical  forces.  Dr.  Jahn  has  performed  experiments  where
participants try to influence the results from great distances,  as  far  as
Russia and New Zealand. Those participants have as strong an effect as those
in the lab. And when participants try to influence the results  days  before
or after the test is run, they too have as strong an effect,  violating  the
principle of causality.

     Dr. Visser finds the larger-scale psychokinesis particularly  difficult
to accept. As we discussed in connection with propulsion,  one  of  Newton's
laws of motion is that every action has an equal and opposite reaction.  Dr.
Visser points out, "If you push something , it will push  back.  I  find  it
difficult to understand how you could hope to do something like  telekinesis
on heavy objects without causing some back reaction that could  damage  that
gray matter in your skull."

     Dr. Jahn's results remain controversial. Some scientists  believe  that
scientific bias has played a role in these experiments, and  that  Dr.  Jahn
has manipulated the data to yield the results he wants. Others feel that the
effect measured is so small, there are many possible ways of explaining  it.
Still others believe his experiments are flawed in some  way.  For  example,
participants are left alone in the room with the random number generator and
might do something to affect it, either  intentionally  or  unintentionally,
such as kicking the machine, waving a magnet near it, or even leaning toward
it and creating some small static electrical effect. Dr. Jahn replies, "It's
silly to think that a lab working on this for twenty  years,  that  has  the
list of achievements we do, would leave itself open to  such  nonsense.  Our
experiments include many layers of protection." Yet a 1988 government review
of Dr. Jahn's work found that  just  one  participant,  responsible  for  15
percent of the trials, is responsible for half of  the  successful  outcomes
measured.

     Dr. Hyman believes that this participant is the laboratory manager  and
the actual designer of the computer program. "For me it's  problematical  if
the one who runs the lab is the only one producing the  results."  This  may
explain why no other lab has been able to reproduce Dr. Jahn's results.  The
government review concluded that if the subject's trials  are  removed  from
the data, the experiments yield only a tiny effect,  one  more  possible  to
have occurred by chance. Yet Dr. Jahn counters, "The report  is  desperately
outdated . It's also simply not true. If you look at the figures, there  are
no spikes or superstars." Dr. Utts, who believes remote viewing is possible,
is skeptical about the ability of the human mind to move objects.

     She has an alternate theory, though, to explain the phenomena.  In  Dr.
Jahn's experiments, participants decide when to press the  button  to  begin
the trial. Dr. Utts believes that participants can look into the future  and
know when the RNG is going to happen to  put  out  a  greater  than  average
number of heads. As we know, over  a  small  number  of  flips,  significant
deviations from chance can occur. When asked to produce  more  heads,  then,
the participant waits until that moment and presses the button. In this way,
she believes , remote viewing  and  psychokinesis  work  in  the  same  way,
through precognition. Even if such abilities do exist, they  aren't  on  the
level of those associated with the Force. Unfortunately, you won't  soon  be
throwing pieces of equipment at your enemies or  lifting  droids  with  your
mind.

     Dr. Jahn, though, believes we might someday build machines sensitive to
our minuscule mental efforts, machines that might respond  by  carrying  out
some task for us. In the meantime, you still might be able to influence when
radioactive decay occurs. And this may come in handy if you find yourself in
a sealed cell with a  blaster  aimed  at  you,  and  that  blaster  will  be
triggered by a radium atom's radioactive decay....



     IGUANA AND JEDI MASTER?


     A  few  of  my  favorite  parapsychological  experiments  explore   the
following compelling questions: * Why do slot machines  tend  to  give  huge
payouts during full moons? * Can humans affect  the  growth  of  algae  with
their minds?

     * Do cockroaches have psychokinetic powers? Since Star Wars aliens  are
able to access the Force, we might expect that  animals  can  as  well.  One
bizarre study tested baby chicks for psychokinetic abilities. The experiment
used a self-propelled robot built by Dr. R. Tanguy, which looked rather like
a small Artoo unit. It had two wheels and one fixed leg, and was driven by a
random number generator. The random numbers told the robot how to  move  its
two wheels. The wheels, controlled by separate motors,  might  move  in  the
same direction, driving the robot forward or backward , or they  might  move
in opposite directions, rotating the robot clockwise or counterclockwise.

     The robot was constrained to stay on a rectangular surface  three  feet
by five feet and move randomly around on it. Dr. Rene Peoc'h,  working  with
the French Foundation Marcel et Monique Odier de Psycho-physique, wanted  to
test whether the chicks could influence the movement of  the  robot.  Chicks
like light during daytime hours, and they will cry out if suddenly put  into
darkness. Dr. Peoc'h put the chicks in a box on the rectangular surface with
the robot. The chicks were put on the right side of the surface.  A  lighted
candle was put on top of the robot and the  lights  turned  out.  Could  the
chicks influence the robot to bring the candle near, banishing the darkness?

     Dr. Peoch measured how much time the robot spent on the  left  half  of
the board versus how much time it spent on the right. In 71 percent  of  the
trials involving the chicks, the robot spent more time on the right half  of
the board, nearer the chicks, than the left half. In trials  with  an  empty
box and no chicks, the robot spent equal amounts of time on either  side  of
the board. After reading this, I toyed briefly with the idea of  testing  my
iguana,  Igmoe,  for  telekinetic  powers.  I  came  up  with  the   perfect
experiment: mount a heat lamp on top of a robot and see if  the  heat-loving
Igmoe can make the robot bring the lamp close for his comfort.

     Then I realized Igmoe  already  has  complete  control  over  his  heat
comfort. I am the robot, responding to Igmoe's  every  desire,  adding  heat
lamps, taking away heat lamps, letting him outside  and  then  back  inside.
Perhaps he does have the Force.  But  does  that  mean  I'm  weak-minded?  I
mentioned earlier a 1988 government review of Dr. Jahn's work.  This  review
actually studied a much wider range of research , encompassing all the  best
evidence for paranormal abilities .

     The survey was conducted  by  the  National  Research  Council  at  the
request of the U. S. Army. If any paranormal abilities exist, the Army wants
their soldiers to have them. After all, soldiers are told to  "Be  all  that
you can be." In discussing the possible applications of  paranormal  powers,
the report mentions "intelligence gathering, .  .  .  planting  thoughts  in
individuals without their knowledge." Authors of the report also envision  a
" 'First Earth Battalion,'  made  up  of  'warrior  monks,'  who  will  have
mastered almost all the techniques under  consideration  by  the  committee,
including the use of ESP, leaving their bodies at will, levitating,  psychic
healing, and walking through walls." Sounds like the Jedi  Knights,  doesn't
it?

     Unfortunately, the report  concluded  that  there  was  "no  scientific
justification from research conducted over a period of  130  years  for  the
existence of parapsychological phenomena." Dr. Hyman,  who  participated  in
the review, agrees. "There's a lot of evidence. It may not be good evidence,
but it's evidence." Yet Dr. Utts believes, "We have proven it. But  I  don't
think we'll get out of this impasse with skeptics until we come up  with  an
explanation.

     And I understand that. As a statistician, I look  at  data  differently
than a physicist. I think we've got the data, we've  got  the  proof."  Even
skeptics like Dr. Hyman, though, "leave the door open. This issue of whether
psi is real or not is not going to be  settled  in  my  lifetime."  And  the
National Research Council, despite the negative findings  in  their  report,
recommend  that  future  research  in  psychokinesis,  remote  viewing,  and
telepathy be monitored by the Army.

     Just in case. An experiment  that  proves  once  and  for  all  whether
psychic powers exist remains elusive. Yet  it  may  be  that  someday  these
controversial experimental  results  will  be  taken  for  granted,  perhaps
explained, and maybe even controlled. Yoda would prefer it that  way.  While
Earth has not yet provided evidence of a power like the  Force,  we  may  be
measuring phenomena that defy our current  understanding  of  the  universe.
Even if such results are explainable by experimental error or other factors,
though, the truth remains that at the quantum level, while we  can  describe
what occurs, we have no idea why it occurs or  even  how  it  occurs.  These
mysteries remain to be understood, and in  finally  understanding,  we  will
discover fascinating and bizarre new truths about  the  world  in  which  we
live, as well as yet more mysteries.

     That is the excitement and the  challenge  of  science.  While  science
remains a long way behind "a galaxy far, far away," we've made great strides
in catching up with George Lucas 's vision in  the  twenty-two  years  since
Star Wars first arrived on movie screens. A vision of a universe filled with
planets and aliens that seemed impossible then seems quite possible now.

     And technology that seemed outlandish  and  physically  impossible  now
seems reasonable and theoretically within our grasp. Perhaps in a  few  more
thousand years, we'll be living in a world much more like Star Wars than  we
ever dreamed.