“The innermost star in orbit.”
“In orbit around what?”
“Chandra,” said Bilson simply.
Pirius, for all his fatigue, felt a thrill of anticipation.
Blue called, “And what is that cloud around the star? Dust, rock—”
“Wreckage,” Bilson said. “The hulks of human ships — greenships, Spline. Some other designs I can’t recognize. Older ones, perhaps.”
Burden said grimly, “Even here the Galaxy is littered with corpses.”
“Xeelee in the scopes,” Bilson said softly. “They know we’re here. Pilot, we don’t have much time.”
“So we’re not the first to come this way,” Pirius said crisply. “Let’s make sure we’re the last. Defensive formation, seven-fold — come on, you know the drill.”
The greenships slid into place around him and the squadron edged forward. Pirius scanned the sky, looking for Xeelee fighters, and for Chandra, the strange black hole that was his final destination.
Chapter 55
In this age of matter the proto-Xeelee found new ways to survive. Indeed, they prospered. They formed new levels of symbiosis with baryonic-matter forms. The new form — a composite of three ages of the universe — was the kind eventually encountered by humans, who would come to call them by a distorted anthropomorphic version of a name in an alien tongue: they were, at last, Xeelee.
But soon the new Xeelee faced an epochal catastrophe of their own.
They still relied on the primordial black holes, formed in the earliest ages after the singularity; they used the holes’ twisted knots of spacetime to peel off their spacetime-defect “wings,” for instance. But now the primordial holes were becoming rare: leaking mass-energy through Hawking radiation, they were evaporating. By the time humanity arose, the smallest remaining holes were the mass of the Moon.
It was devastating for the Xeelee, as if for humans the planet Earth had evaporated from under their feet.
But a new possibility offered itself. New black holes were formed from the collapse of giant stars, and at the hearts of galaxies, mergers were spawning monsters with the mass of a million Sols. Here the Xeelee migrated. The transition wasn’t easy; a wave of extinction followed among their diverse kind. But they survived, and their story continued.
And it was the succor of the galaxy-center black holes that first drew the Xeelee into contact with dark matter.
There was life in dark matter, as well as light.
Across the universe, dark matter outweighed the baryonic, the “light,” by a factor of six. It gathered in immense reefs hundreds of thousands of light-years across. Unable to shed heat through quirks of its physics, the dark material was resistant to collapse into smaller structures, the scale of stars or planets, as baryonic stuff could.
Dark and light matter passed like ghosts, touching each other only with gravity. But the pinprick gravity wells of the new baryonic stars were useful. Drawn into these wells, subject to greater concentrations and densities than before, new kinds of interactions between components of dark matter became possible.
In this universe, the emergence of life in dark matter was inevitable. In their earliest stages, these “photino birds” swooped happily through the hearts of the stars, immune to such irrelevances as the fusion fire of a sun’s core.
What did disturb them was the first stellar explosions — and with them the dissipation of the stars’ precious gravity wells, without which there would be no more photino birds.
Almost as soon as the first stars began to shine, therefore, the photino birds began to alter stellar structures and evolution. If they clustered in the heart of a star they could damp the fusion processes there. By this means the birds hoped to hurry a majority of stars through the inconvenience of explosions and other instabilities and on to a dwarf stage, when an aging star would burn quietly and coldly for aeons, providing a perfect arena for the obscure dramas of photino life. A little later the photino birds tinkered with the structures of galaxies themselves, to produce more dwarfs in the first place.
Thus it was that humans found themselves in a Galaxy in which red dwarf stars, stable, long-lived and unspectacular, outnumbered stars like their own sun by around ten to one. This was hard to fit into any naturalistic story of the universe, though generations of astrophysicists labored to do so: like so many features of the universe, the stellar distribution had been polluted by the activities of life and mind. It would not be long, though, before the presence of the photino birds in Earth’s own sun was observed.
The Xeelee had been troubled by all this much earlier.
The Xeelee cared nothing for the destiny of pond life like humanity. But by suppressing the formation of the largest stars, the birds were reducing the chances of more black holes forming. What made the universe more hospitable for the photino birds made it less so for the Xeelee. The conflict was inimical.
The Xeelee began a grim war to push the birds out of the galaxies, and so stop their tinkering with the stars. The Xeelee had already survived several universal epochs; they were formidable and determined. Humans would glimpse silent detonations in the centers of galaxies, and they would observe that there was virtually no dark matter to be observed in galaxy centers. Few guessed that this was evidence of a war in heaven.
But the photino birds turned out to be dogged foes. They were like an intelligent enemy, they were like a plague, and they were everywhere; and for some among the austere councils of the Xeelee there was a chill despair that they could never be beaten.
And so, even as the war in the galaxies continued, the Xeelee began a new program, much more ambitious, of still greater scale.
Their immense efforts caused a concentration of mass and energy some hundred and fifty million light-years from Earth’s Galaxy. It was a tremendous knot that drew in galaxies like moths across three hundred million light-years, a respectable fraction of the visible universe. Humans, observing these effects, called the structure the Great Attractor — or, when one of them journeyed to it, Bolder’s Ring.
This artifact ripped open a hole in the universe itself. And through this doorway, if all was lost, the Xeelee planned to flee. They would win their war — or they would abandon the universe that had borne them, in search of a safer cosmos.
Humans, consumed by their own rivalry with the Xeelee, perceived none of this. To the Xeelee — as they fought a war across hundreds of millions of light-years, as they labored to build a tunnel out of the universe, as stars flared and died billions of years ahead of their time — humans, squabbling their way across their one Galaxy, were an irritant.
A persistent irritant, though.
Chapter 56
The seven surviving greenships of Exultant Squadron formed up into a tight huddle. In the sudden calm, the crews gazed around at the extraordinary place they had come to.
Of all the Galaxy’s hundreds of billions of stars, SO-2 was the one nearest the black hole. And now they were within its orbit. This central place, a cavity within a cavity light-weeks across, was free of stars — because any star that came closer than SO-2 would be torn apart by black hole tides. It was filled with light and matter, though, with glowing plasma, but Pirius’s Virtual filters blocked that out. It was as if the seven of them hovered within a great shell walled by crowded stars, like flies inside a Conurbation dome.
And at the very center of this immense space was a pool of light. From this distance it was like a glowing toy, small enough to cover with a thumbnail held at arm’s length. It was a floor of curdled and glowing gas, as wide as planetary orbits in Sol system. This was the black hole’s accretion disc, the penultimate destination of debris infalling from the rest of the Galaxy — the place where doomed matter was compressed and smashed together, whirling around the hole like water around a leak in a bucket, before it fell into the black hole.