Tides of Light

by Gregory Benford

  But even as he said it, he knew that something different brewed in him.

  The shadowy presence that had sat beyond view of his inner self now moved with sluggish purpose. Into his mind flashed the coordinates and routes necessary to take a desperate band of pilots within reach of the great accretion disk at True Center. The data-flow was a torrent, thick and fast and coming from a source he could not clearly sense. Perhaps a deep-carried Aspect? But no, another portion of himself denied it. What, then?

  He chuckled ruefully to release the tension such thoughts brought, and for a darting moment saw himself down a long telescoping tunnel of immense perspective, glimpsing himself as a member of a phylum—that of the laughing, dreaming vertebrates.

  THE COLLECTED

  >The thing with plenty legs, it said I was a monument to my kind.

  >There was a team of five of the little ones and a big one with funny legs and they cut me up slowly to see.

  >My mother was there with parts of animals growing out of her and when I tried to get to her they did that to me, too.

  >I was kept in my fighting suit like being laid to rest only there were these maggots that kept bursting out from puckers in my skin and crawling all over me.

  >They said I would not feel the things that went in through my eyes but they lied.

  >I think they forgot all about me and let me lie there on the floor while they worked on the others and finally decided to just use me for parts.

  >I could see pretty well but looked down and there was no body, just my head on a pike they carried around with them, I figure to scare other members of my ’Sembly in battle, with me pleading and screaming most of the time but without lungs.

  The Galactic Center was a collection of debris swirling at the bottom of a gravitational pothole. Its howling, riotous inner precincts were by this time well guarded by mech fleets.

  But worms made it traversable. The first human expeditions through the wormhole mouth had been successful. It opened upon a site nearer to True Center. Paris himself had flown through it, darting in and back like a mouse dashing anxiously from its hole. And so they were—pests in the walls.

  They flew through in order, then met on convergent asymptotes. Paris demanded and got a role in the assault. He was an accomplished pilot, easily able to angle in on the wormhole at high speeds, with a nudge here and a twist there.

  Wormholes were fossils of the first split second of the universe. They were held open by onionskin layers of negative energy, sheets of anti-pressure made in that primordial convulsion. As natural resources, they had been gathered—by whom?—billions of years before and brought here, to serve as a transport nexus.

  Quantum froth fizzed at the worm-mouth rim, a gaudy spray of burnt hues. These “struts” were of unimaginable density, but danger lurked only at the rim, where stresses would tear ordinary matter into virulent plasma. To hit the walls of the constantly shifting, oblong target, would be fatal, as several pilots had inadvertently proved.

  The mouth was now an ellipsoid rimmed in quantum fire. He flew a pencil-thin ship, its insulation slight, safety buffers minimal. Yet he somehow felt no fear, only a serene certainty. Tidal stresses wrenched squeals from his ship as lightning curled in snakes of violet and gold—

  —and he was tumbling out the other end, in a worm complex over a hundred light-years away.

  A blue-green star majestically greeted the human fleet with a coronal plume. Nearby orbited a mech complex; picket craft policed it. With quick swerves the tiny human ships angled into a traffic-train headed for a large wormhole mouth. Fifty men and eighty-six women had died learning the route they would follow, gaining the override codes to pass through the mech complexes. But their disguises would withstand only a moment’s inspection; daily and they were dead.

  Their second transit was through a spacious wormhole that left them racing in low orbit over a smoldering red dwarf. They could use their hard-won code-status perhaps a few more times before the mech complexes would catch on. They had to take whatever wormhole mouths they could get.

  Wormholes could take traffic only one way at a time. High-velocity ships plowed down the wormhole throats, which could vary from a finger’s length to a planet’s diameter. A jump through could leave one near mysteriously useless solar systems, or in virulent places that would fry a human in seconds.

  Long before, presumably by brute-force interstellar hauling, someone—perhaps those who had made the earliest mechs?—had built an elaborate system at Galactic Center. Smaller worm mouths, massing perhaps as much as a mountain range, allowed only thin-ships to pass. These Paris and the other eighteen volunteers chose when they popped out in a mech complex. They never slowed; each network site was well policed, and speed was their only defense.

  Shoot through a worm mouth, aim for a small worm mouth nearby, go. The snaky, shiny worm-walls zoomed by as Paris lay watching his displays and trying not to think of what was coming.

  The tapering gray sheen of the throat flexed. Each worm mouth kept the other “informed” of what it had just eaten, the information flowing as a surge in the tension of the wormhole itself. Stress waves sent clenching oscillations, making the throat ripple like sausage links. If a sausage neck met him, tightened too fast, he would emerge as a rosy plume of ionized gas at the exit mouth.

  From an elaborate wormhole calculus human theorists had worked out the route to follow. Between Isis and the space near True Center were a dozen wormhole jumps. Worse, some wormholes had multiple mouths, so the sleek throat split into choices—selections they had to make at immense speed.

  Suns and planets of great, luminous beauty floated in the distant blackness when they emerged. Behind the resplendent nebulae loomed the radiant promise of True Center. It seemed a strange contrast, to leap about the vast distances while boxed into a casket-size container.

  Blink-quick, they jumped and dodged and jumped again.

  Subtlety was wasted here; when a mech craft approached on a routine check, they destroyed it with kinetic energy bolts. Mechs never used such crude methods, so they were leaving behind clear signs that “vermin” had passed that way.

  They emerged amid an eerie halo of white-dwarf stars, arranged in a hexagonal. Paris wondered why mechs would arrange such a pattern, which from simple orbital mechanics could not last. But like so many mech traits, this had no explanation, even in Arthur’s huge memory stores, nor any likelihood of one.

  Ahead, the galactic disk stretched in luminous splendor. Lanes of clotted dust framed stars azure and crimson and emerald. This wormhole intersection afforded five branches: three black spheres orbited like circling lethal leopards, while two cubes blared bright with quantum rim radiation.

  Their pencil ships thrust directly into a flat face of a cubic worm. The negative-energy-density struts that held the wormhole open were in the edges, so the faces were free of tidal forces. A flicker, a stomach-twisting wrench—and they were near True Center.

  The inner disk glowed with fermenting scarlets and mean purples. Great funnels of magnetic field sucked and drew in interstellar dust clouds. Sullen cyclones narrowed toward the brilliant accretion disk.

  Mech contrivance orbited everywhere here, filling a bowl of sky alive with activity. Vast gleaming grids and reflectors caught radiation from the friction and infalling of the great disk. This crop of raw photon energy was flushed into the waiting maws of wormholes, apparently moving the flux to distant worlds in need of cutting lances of light. For what—mech planet-shaping, world-raking, moon-carving?

  They flitted into yet another wormhole mouth—

  —and the spectacle made him hold his breath.

  Magnetic filaments towered, so large the eye could not take them in. Through them shot immense luminous corridors alive with wriggling energies. These arches yawned over tens of light-years, their immense curves descending toward the white-hot True Center. There matter frothed and fumed and burst into dazzling fountains.

  At True Center, three million sun
s had died to feed gravity’s gullet. The arches were plainly artificial, orderly arrays of radiance a light-year across. Yet they sustained themselves along hundreds of light-years, as gauzy as a young girl’s hair as they churned with airy intricacy.

  Could intelligence dwell here? There had been ancient stories, never confirmed. Emerald threads laced among tangled ruby spindles. He had a powerful impression of layers, of labyrinthine order ascending beyond his view, beyond simple understanding.

  Hard acceleration rammed him back into his flow-couch. From behind, a torrent of malignant light.

  They have detonated the worm! came a cry over comm.

  Braking hard, veering left into a debris cloud—

  Evidently mechs knew how to trigger the negative-energy-density struts inside a worm mouth—and would do so to catch vermin. Now their line of retreat was gone.

  They fled to a huge blot that beckoned with the promise of sullen shelter. They were close to the edge of the black hole’s accretion disk. Around them churned the deaths of stars, all orchestrated by the magnetic filaments. Which in turn, Paris was quite sure, worked to the command of something he did not care to contemplate. Did mechs govern here, or had he ventured into a realm where even they were vermin?

  Here stars were ripped open by processes he could not fathom—spilled, smelted down into fusing globs. They lit up the dark, orbiting masses of debris like tiny crimson match heads flaring in a filthy coal-sack.

  Amid this swam the strangest stars of all. Each was half-covered by a hanging hemispherical mask. This shroud gave off infrared, a strange screen hanging at a fixed distance from each star. It hovered on light, gravity just balancing the outward light pressure. The mask reflected half the star’s flux back on it, turning up the heat on the cooker, sending virulent arcs jetting from the corona.

  Light escaped freely on one side while the mask bottled it up on the other. This pushed the star toward the mask, but the mask was bound to the star by gravitation. It adjusted and kept the right distance. The forlorn star was able to eject light in only one direction, so it recoiled oppositely.

  The filaments were herding these stars: sluggish, but effective. Herded toward the accretion disk, stoking the black hole’s appetite.

  Paris and the others hung in a narrow gulf overlooking the splendor below. Blackness dwelled at the core, but friction heated the infalling gas and dust. Storms worried these great banks; white-hot tornadoes whirled. A virulent glow hammered outward, shoving incessantly at the crowded masses jostling in their doomed orbits. Gravity’s gullet forced the streams into a disk, churning ever inward.

  Amid this deadly torrent, life persisted. Of a sort.

  He peered through the gaudy view, seeking the machine-beasts who ate and dwelled and died here. Records millennia old told of these. There.

  Suffering the press of hot photons, a grazer basked. To these photovores, the great grinding disk was a source of food. Above the searing accretion disk, in hovering clouds, gossamer herds fed.

  Vector that way, came the command. This way led to their target, but already mechs were moving toward the spindly human ships.

  Sheets of the photovores billowed in the electromagnetic winds, luxuriating in the acrid sting. Some seemed tuned to soak up particular slices of the electromagnetic spectrum, each species with a characteristic polish and shape. They deployed great flat receptor planes to maintain orbit and angle in the eternal brimming day.

  The human ships slipped among great wings of high-gloss moly-sheet. The photovore herds skated on winds and magnetic torques in a complex dynamical sum. They were machines, of course, presumably descended from robot craft which had explored this center billions of years before. More complex machines, evolved in this richness, prowled the darker lanes farther out.

  A bolt seared through the dust and struck a human ship. Another lanced through some photovores, which burst open in flares.

  They hugged the shadow and waited. Moments tiptoed by.

  A contorted shape emerged from a filmy dust bank, baroquely elegant in a shape no human mind could have conceived, ornate and glowing with purpose, spiraling lazily down the gravitational gradients. Paris saw a spindly radiance below the photovore sheets. A magnetic filament, he guessed. His Arthur Aspect broke in,

  I was here once, in my Aspect manifestation, during the glorious era when we were allowed this close. I advise that you shelter there, for the guardian ship approaching is lethal beyond even my comprehension.

  “Your memory is that good?”

  This was merely 3,437 years ago. I have suffered some copying errors, true, but fear is still the most potent stabilizer of recall. I was quite terrified during my carrier’s incursion here. She was one of three who survived that, out of over a thousand.

  “I don’t know…”

  His intuition failed him. The other human pencil ships zoomed all around, sending panicked transmissions that he could scarcely filter. The ornate mech craft lumbered down toward them, many hundreds of kilometers away but still close, close, in the scales of space battle.

  We are surely doomed if we stay here. If you are losing at a game, change the game.

  Paris nodded and sent a compressed signal to the others. At full power he slipped below the shiny sheets of photovores, their outstretched wings banking gracefully on the photon breeze. Storms worried the flocks. White-hot tornadoes whirled and sucked, spun off from the disk below. When fire-flowers blossomed in the disk, a chorus arose from the feeding layers. Against the wrathful weather, position-keeping telemetry flitted between the herd sheets. They sang luminously to each other in the timeless glare.

  Paris watched one herd fail. Vast shimmering sheets peeled away. Many were cast into the shrouded masses of molecular clouds, which were themselves soon to boil away. Others followed a helpless descending gyre. Long before they could strike the brilliant disk, the hard glare dissolved their lattices. They flared with fatal energies.

  He felt, in the ship’s bubble-sensorium, fresh attention focused on him. Lenses swiveled to follow: prey?

  Here a pack of photovores had clumped, caught in a magnetic flux tube that eased down along the axis of the galaxy itself. Among them glided steel-blue gammavores, feeders on the harder gamma-ray emission from the accretion disk. Arthur said,

  These sometimes fly this far above the disk, as I recall, to hunt the silicate-creatures who dwell in the darker dust clouds. Much of the ecology here was unknown in my time, and humans were banished from such territories before we could well explore. We sought the Wedge, the place where the earliest humans had taken shelter, including the legendary Walmsley. We wished to find there the rumored Galactic Library, a wealth which could have aided—

  “Fine, stick to business.”

  He stopped the Aspect’s idle musing with an internal block. Time to move. Where? Into the magnetic tube. But could they draw down some concealing cover?

  He swooped with the others toward the filament. This also angled them toward a huge sailcraft photovore. It sighted them, pursued.

  Here navigation was simple. Far below them, funneling away to an infinite well, lay the rotational pole of the Eater of All Things, the black hole of three million stellar masses: a pinprick of absolute black at the center of a slowly revolving, incandescent disk.

  The metallivore descended after them, through thin planes of burnt-gold light seekers. The pencil ships scattered, firing ineffectually at it. They had speed, it had durability.

  “How the hell do we deal with that?”

  The metallivore prunes less efficient photovores. Its ancient codes, sharpened over time by natural selection, prefer the weak. Those who have slipped into unproductive orbits are easier to catch. It also prefers the savor of those who have allowed their receptor planes to tarnish with succulent trace elements, spewed up bythe hot accretion disk below. The metallivore spots these by their mottled, dusky hue. Each frying instant, millions of such small deaths shape the mechsphere. “We need something to zap it!”
>
  I shall ponder. Meanwhile, be fleet of foot.

  He veered and sheered, letting his feel for the craft take over. Others were not so swift; he heard the dying cries of three people nearby.

  These placid conduits all lived to ingest light and excrete microwave beams, but some—like the one gliding after the tiny human ships—had developed a taste for metals: a metallivore. It folded its mirror wings, became angular and swift, accelerating.

  The higher phyla are noticing us.

  “Coming damned fast, too.”

  Plants harness only one percent of the energy falling upon them. Here photovoltaics capture ten percent, and evolution acting upon the mechs has improved even that. Admirable, in a way, I suppose—

  “Give it to me compressed, not true-voice.” An Aspect always tried to expand his airing time.

  Arthur sent a squirt of compacted ancient lore—Fusion fires, he said, inside the photovores digested the ruined carcasses of other machines. Exquisitely tuned, their innards yielded pure ingots of any alloy desired.

  The ultimate resources here were mass and light. The photovores lived for light, and the sleek metallivore lived to eat them—or even better, the human ships, an exotic variant. It now gave gigahertz cries of joy as it plunged after them into the magnetic fields of the filament.

  “These magnetic entities are intelligent?” he asked.

  Yes, though not in the sense we short-term thinkers recognize. They are more like fitfully sleeping libraries. I have an idea. Their thinking processes are vulnerable.

  “How?”

  They trigger their thinking with electrodynamic potentials. We are irritating them, I am sure.

  He saw the metallivore closing fast. Beyond it came the convoluted mech guardian ship, closing remorselessly.

  The remaining human ships executed evasions—banks, swoops, all amid the pressing radiance from the disk-glare. Around them magnetic strands glowed like smoldering ivory.

  The metal-seeker would ingest them with relish, but with its light-wings spread to bank it could not maneuver as swiftly as their sleek ships. Deftly they zoomed through magnetic entrails. The mech ship followed.