Scanned from FAR HORIZONS (edited by Robert Silverberg) [story 09]

THE GALACTIC CENTER SERIES
Gregory Benford
In the Ocean of Night (1977)
Across the Sea of Suns (1984)
Great Sky River (1987)
Tides of Light (1989)
Furious Gulf (1994)
Sailing Bright Eternity (1995)

The series comprises six novels, composed over a twenty-five-year span. The events stretch from the early 2000s to a.d. 37518, an immense scope imposed because its central focus, our galactic center, is 28,000 light-years away, and characters had to get there to take part in the galaxy's larger games.
But as well, I wanted to convey the huge scales of both time and distance that a galaxy implies. We are mayflies on the stage lit by the stars, and science fiction should remember that.
In the Ocean of Night, published in 1977, explored our discovery that computer-based life seemed dominant throughout the galaxy. A British astronaut in NASA's space program, Nigel Walmsley, had uncovered the implication that "evolved adding machines," as he put it, had inherited the ruins of earlier, naturally derived alien societies. We realized this by finding wrecked craft on the moon, and because a roving machine from an ancient interstellar society enters the solar system to study it.
Across the Sea of Suns follows Walmsley on the first manned interstellar expedition. Drawn by curiosity, humans want to know more about nearby stars, where there are aliens of very strange properties. There Walmsley finds that Naturals-organic beings like us-have been annihilated or at least greatly hampered by the galaxy's pervasive machine societies.
During this flight Earth is invaded by an ocean-living species, as a method the machine-based civilizations use to disrupt any advanced Natural society. As soon as others know of our presence, they seek to wipe us out, as feared Natural rivals. The novel concludes with a few remaining people, including Walmsley, capturing a sophisticated interstellar ship. They head for the galactic center, to find out what's going on.
In our galactic core, within a few light-years of the exact center, there are a million stars within a single light-year. Imagine having several stars so close they outshine the moon!
Worse, the galactic center was the obvious place for machines to seek. Virulent gamma rays, hot clouds, and enormously energetic processes dominate the crackling activity.
Great Sly River opens on this landscape; the title refers to the ancient American Indian name for the Milky Way. Its central figure is a man named Kileen, who flees with his Family Bishop across a ruined landscape. Its sky is dominated by the black hole at True Center, which his people call the Eater of All Things-though they don't quite know why.
In this ravaged panorama humans have fallen from grace. Though the Walmsley-led expedition reached the Center and did well there, building a considerable civilization, they could not evade the superiority of machines. Pursuing them is an enigmatic mech, or machine, the Mantis, who views humans as an endangered species, their extinction inevitable. It wishes to record what it finds worthy in the few remaining societies. Not since humans lived in immense space stations called Chandeliers have they been on even terms with the mechs.
The Bishops flee their home world, Snowglade, in hopes of finding refuge and a solution to their many riddles about the true nature of mechs closer to the black hole. In the fourth novel, Tides of Light, they reach another planet and form an alliance with another organic species, one also endangered by the relentless mechs. We meet other kinds of mechs, too. Machines which can reproduce themselves would inevitably fall under the laws of natural selection, and would specialize to use local resources. The entire panoply of biology would recapitulate: parasites, predators, prey.
The Bishops deal with this while trying to fathom enigmatic messages from an intelligence lodged in the magnetic strands that loom throughout the Center. It tells of a place, the Wedge, where humans might find refuge and perhaps discover the legendary Galactic Library, which comprises a history of the entire galaxy.
In the fifth novel, Furious Gulf, we enter the gulf around the powerful black hole, and see another kind of gulf, that between intelligences bom of different realms. Our human concern with mortality and individualism as a
feature of biological creatures is unnecessary among intelligences that never had to pass through our Darwinnowing filter.
If we can copy ourselves indefinitely, why worry about a particular copy? What kind of society would emerge from such origins? What would it think of us-us Naturals, still hobbled by our biological destiny?
A slowly emerging theme in these novels, then, is how intelligence depends on the "substrate," whether in evolved humans or adaptive machines-both embodying intelligence, but with wildly different styles.
Since the second novel we had not seen Nigel Walmsley, though there are hints that he was active near True Center much earlier. Much history echoes in ruins and enigmatic messages. Finding and entering the Wedge finally brings signs of humans who have sustained themselves against the mechs, though in a bewildering folded space-time (the s-t, or esty).
Sailing Bright Eternity, book six, finished in 1995, pulls all the series' major characters together. In the Wedge they find that humans themselves have been carrying information they did not know they had, data crucial to stopping the mechs from erasing all Natural life.
It had been twenty-five years since I started on In the Ocean of Night, and our view of the galactic center had changed enormously. Some parts of the first two books, especially, are not representative of current thinking. Error goes with the territory.
The themes of the series resolve in favor of humanity as unique and worth saving, even in as hostile a galaxy as I envisioned. But I suspect that if natural life is as foolish and vulnerable as we seem to be, quite possibly machines may inherit the galaxy, and thus sit bemused, watching us with cool indifference from afar.
This added story deals with an essential question asked of humans at the beginning of their decline, about a.d. 36000. It also reveals several aspects of the dreaded Mantis I never found room for in the novels.
-Gregory Benford