Tides of Light

by Gregory Benford

  “It’s moving toward the poles,” Shibo said, her voice a smooth lake that showed no ripples.

  The hoop glowed brighter and flattened more and more as its inner edge approached the center of New Bishop. Killeen felt suspended, all his hopes and designs dashed to oblivion by this immense simple thing that sailed so blithely through a planet.

  “Where…where’d it come from?”

  Cermo bit his lip in frustration. “From nowhere, Cap’n, I swear. When I saw it first it was dim, just barely there.”

  “Where?”

  “It was startin’ in on cuttin’ the air. Musta come from further out and just ran smack into New Bishop.”

  Killeen did not believe this for a moment. He scowled.

  Shibo said, “It lit up on impact?”

  Cermo nodded. “I’d seen it before if it was bright.”

  “So it’s drawing its light from what it’s doing to the planet,” she deduced, her eyes distant. “That’s why we didn’t see it before.”

  Killeen wondered momentarily how she could remain so abstract while confronting events so huge. His own imagination was numbed. He struggled to retain some grip on events by digressing into detail. “How…how thick is it?”

  Shibo’s glance told him that she had noticed the same strange sharpness. “Smaller than the Argo, I’d judge,” she said, her eyes narrowing.

  “That small,” Cermo said distantly, “but it’s cutting through all that.”

  Shibo said, “Planet does not split.”

  Cermo nodded. “It’s holdin’ together. Some places you can see where the thing’s cut through rock and left a scar. But the rock closes up behind it.”

  “Pressure seals scar again,” Shibo agreed.

  “It’s no kind knife I ever saw,” Killeen said, and instantly regretted making such an empty statement. In the face of a thing like this, the crew had to believe their Cap’n wasn’t as dazed as they were. Doubtless, many had already seen the golden hoop from other parts of the ship. It might throw them into blind panic. Killeen’s own impulse had been to get away from the thing as fast as possible. That might, indeed, be the smart thing to do. But they had come so far….

  Toby asked, “D’you think…maybe it’s not like a knife at all. Could be some thing lives off planets? Eats ’em?”

  The idea was both absurd and also not dismissable, Killeen thought. Reasonableness was no guide here.

  “If it eats all that rock, howcome it’s so thin?” he said with elaborate casualness. Besen laughed merrily and somehow the meaningless joke relaxed the small party.

  “Why would mechs make it, then?” Toby persisted.

  Killeen noted ruefully that no one considered for a moment the possibility that humans might have ’factured such a thing. The glittering, jewellike Chandeliers had been the peak of human endeavor, ages ago. The numbing simplicity of this glowing ring immediately spoke of an alien mind at work here, acting through majestic perspectives.

  The mute indifference of this glowing thing was the final judgment against them all, Killeen thought. Their endless ruminations and longings had invested their destination with such weight, and now this silent slicing of their freshly named world ended all speculation. Fragile humanity could not live on such a vast canvas, the plaything of forces beyond fathoming. Their quest had ended in disaster even before they could set foot on the soil of their new paradise.

  “Hey, maybe Argo can do somethin’ ’bout that thing,” Toby said eagerly.

  Loren joined in. “Yeasay, ask the systems if they can cook somethin’ for that.”

  Killeen had to smile, though he did not take his eyes from the screen. A sixteen-year-old boy knew no constraints, could imagine no problem that he could not meet with the right measure of savvy and sheer boundless bursting energy. And who was he to say no?

  “Try,” he said to Shibo, gesturing with one hand.

  She worked over the control pads for long moments, lines creasing her face in concentration. Finally she slapped the console and shook her head. “No memory. Argo doesn’t recognize this thing.”

  Killeen summoned up all his Aspects. They were happy for even momentary attention but only one had any useful idea. This was Grey, a woman from the High Arcology Era. She was a somewhat truncated personality, suffering from sentence-constructing disability because of a transcription error a century before. She knew scientific and historical lore of her own and earlier times. Her voice was halting and cluttered with purring static, heavily accented with the dust of time.

  I believe it…is what was called by theoreticians…a “cosmic string.” They were known…in Chandelier Age…but only theory…hypothetical objects…I studied…these matters in…youth…

  “Looks real to me,” Killeen muttered to himself.

  We believed…they were…made at the very earliest moments…of…universe. You can envision…at that time…a cooling, expanding mass. It failed…to be perfectly symmetrical and uniform. Small fluctuations produced…defects in the vacuum state…states of certain elementary particles—

  What the hell’s that mean? Killeen thought irritably. He was watching the hoop slowly cut through a slate-gray plain. Around him the control vault had fallen into numbed silence. His Arthur Aspect broke in:

  I believe matters could proceed better if I translated from Grey for you. She is having difficulty.

  Killeen caught the waspish, haughty air the Aspect sometimes took on when it had been consulted too infrequently for its own tastes. He remembered his father saying to him once, “Aspects smell better if you give ’em some air” and resolved to let them tap into his own visual and other sensory web more often, to stave off cabin fever. He murmured a subvocal phrase to entice the Aspect to go on.

  Think of ice freezing on the surface of a pond. As it forms there is not quite enough area, perhaps, and so small crinkles and overlaps appear. These ridges of denser ice mark the boundary between regions which did manage to freeze out smoothly. All the errors, so to speak, are squeezed into a small perimeter. So it was with the early universe. These exotic relics are compacted folds in space, tangles of topology. They have mass, but they are held together primarily by tension. They are like cables woven of warped space-time itself.

  “So what?”

  Well, they are extraordinary objects, worthy of awe in their own right. Along their lengths, Grey tells me, there is no impediment to motion. This makes them superconductors!—so they respond strongly to magnetic fields. As well, if they are curved—like this one—they exert tidal forces on matter around them. Only over a short range, however—a few meters. I should imagine that this tidal stretching allows it to exert pressures against solid material and cut through it.

  “Like a knife?”

  Indeed—the best knife is the sharpest, and cosmic strings are thinner than a single atom. They can slide between molecular bonds.

  “So it just slides right through everything,” Killeen mused to himself.

  Yes, but, well—think of what we witness here! A flaw in the continuity of the very laws that govern matter. Nature allows such transgressions small room, and the discontinuity derives a tension from its own wedged-in nature—a stress that communicates along its stretched axis. And so we can see this incomparably slim marvel, because it is bigger than a planet along its length.

  “So why’s this one cutting through New Bishop? It just fall in by accident?”

  I sincerely doubt that such a valuable object would be simply wandering around. Certainly not at Galactic Center, where entities are sophisticated enough to understand their uses.

  “Somebody’s usin’ it? For what?”

  That I do not know.

  Grey’s wispy tones sifted over Arthur’s:

  I heard of astronomers…observed distant strings…but no record…of use. Were born…as relativistic objects…but slowed down…through collisionswith…galaxies…finally came to rest…here…at Center…

  When her voice faded Arthur said:

  I wo
uld imagine handling such a mass is a severe technical difficulty. Since it is a perfect superconductor, holding it in a magnetic grip suggests itself. The sure proof of my view, then, would be fluctuating magnetic fields in the region near the outer part of the hoop.

  Killeen recognized Arthur’s usual pattern—explain, predict, then pretend haughty withdrawal until Killeen or somebody else could check the Aspect’s prediction. He shrugged. The idea sounded crazy, but it was worth following up.

  To Shibo he said, “Can Argo analyze the magnetic fields near that thing?”

  Without answering, Shibo set up the problem. When she thought intensely, Shibo seldom spoke.

  Toby stepped forward eagerly. “Magnetic fields! Sure, I shoulda thought. That magnetic creature, right? ’Member, back on Snowglade? It told us then—look for the Argo, it said. You think it’s maybe followed us here, Dad?”

  His Ling Aspect spat immediately:

  This is a grave crisis you face. Do not let crew get out of hand or you will have even greater difficulty.

  Killeen understood Toby’s exuberance, but Ling was right: Discipline was discipline. “Midshipman, you’ll kindly remain silent.”

  “Well, yessir, but—”

  “What was that?”

  “Uh…aye-aye, sir. But if it is the EM—”

  “You’ll stand at attention, mister, against the wall.” Killeen saw that Besen and Loren were grinning at their mate’s dressing-down, so he added, “All three of you—attention! Until I say otherwise.”

  He turned his back on them and Shibo was at his elbow. “Argo’s detectors report strong fields there. Changing fast, too.”

  “Um-hmm,” Killeen murmured noncommittally. He outlined to Cermo and Shibo, and the eavesdropping midshipmen, what Arthur had conjectured. He resorted to simple pictures, describing magnetic fields as stretched bands that seized and pressed. Nothing more was needed; explanations of science were little better than incantations. None of them had a clear notion of how magnetic fields exerted forces on matter, the geometry of currents and potentials such a phenomenon required, or the arcane argot of cross vector products. Magnetic fields were unseen actors in a world unfathomable to humans, much as invisible winds had driven Snowglade’s weather and ruffled their hair.

  Cermo said slowly, “But…but what’s it for?”

  Killeen said tersely, “Keep a sharp eye.” Cap’ns did not speculate.

  “Maybe caused those gray, dead zones on the planet.” Shibo pointed to the devastated polar regions, which the hoop was now approaching.

  “Um-hmm,” Killeen murmured noncommittally.

  He felt instinctively that they should not fasten on one idea, but leave themselves open. If New Bishop was not a proper refuge for them, he wanted to be damn sure of that fact before launching them on another voyage to some random target in the sky. Now that he had a moment to recover, even this gargantuan glowing hoop had not completely crushed his hopes that they might scratch out an existence here.

  “Why’s it happening now?” Shibo mused.

  “Just as we arrive?” Killeen read her thoughts. “Could be this is what the Mantis wanted us for.”

  “Hope not,” Shibo said with a sardonic twist of her lips.

  “We had plenty bad luck already,” Cermo said.

  Shibo studied the board. “I’m getting something else, too.”

  “Where?”

  “Coming up from near the south pole. Fast signals.”

  “What kind?”

  “Like a ship.”

  Killeen peered at the screen. The glorious squashed circle had cut slightly farther into the planet. It was still aligned with its flattened face parallel to the rotation. He estimated the inner edge would not reach the planet’s axis for several more hours at least. As it intruded farther, the hoop had to cut through more and more rock, which probably slowed its progress.

  Shibo shifted the view, searching the southern polar region. A white dab of light was growing swiftly, coming toward them. It was a dim fleck compared with the brilliant cosmic string.

  “Coming toward us,” she said.

  “Maybe cargo headed for the station, if they’re still carrying out business as usual.” He cut himself short; it did no good to speculate out loud. A crew liked a stony certainty in a Cap’n; he remembered how Cap’n Fanny had let the young lieutenants babble on with their ideas, never voicing her own and never committing herself to any of their speculations.

  He turned to Cermo. “Sound general quarters. Take up positions to seize this craft wherever it comes in.”

  Cermo saluted smartly and was gone. He could just as easily have hailed the squads of the Family from the control vault, but preferred to go on foot. Killeen smiled at the man’s relishing this chance to take action; he shared it. Pirating a mech transport was pure blithe amusement compared with impotently watching the hoop cut into the heart of their world.

  The three midshipcrew left hurriedly, each taking a last glance at the screen where two mysteries of vastly different order hung, luminous and threatening.

  TWELVE

  Killeen glided silently around the sleek craft, admiring its elegant curves and economy of purpose. Its hull was a crisp ceramo-steel that blended seamlessly into bulging flank engines. The capture had been simple, flawless.

  The squad that had seized it hovered near both large airlocks in the ship’s side. They had waited here in the station’s bay, and done nothing more than prevent six small robo mechs from hooking up power leads and command cables to the ship’s external sockets. Without these, the craft floated inertly in the loading bay.

  It was clearly a cargo drone. Killeen was relieved and a little disappointed. They faced no threat from this ship, but they would learn little from it, as well.

  It is of ancient design. I recall the mechs using such craft when they transported materials to Snowglade. I believe I could summon up memories of how to operate them, including the difficulties of atmospheric reentry. They were admirably simple. People of times before mine often hijacked them for humanity’s purposes.

  Arthur’s pedantic, precise voice continued as Killeen inspected the loading bay. Arthur pointed out standard mechtech. The Aspect was of more use here, where older, high-vacuum tech seemed to have changed little in the uncounted centuries since humanity had been driven from space altogether. On Snowglade the mechs had adapted faster than humans could follow, making the old Aspects nearly useless. Arthur’s growing certainty about their surroundings in this station began to stir optimism in Killeen.

  Flitters! See there?

  A squad member, exploring nearby in the station, had fumbled her way through a lock. A large panel drew aside, revealing a storehouse of sleek ships similar to the cargo drone they had just seized.

  These are quick little craft that can reach the surface with ease. I remember them well. We termed them Flitters because they move with darting ease in both atmosphere and deep space. Admirable for avoiding interception. That was before the Arcologies lost control of their orbital factories. Before the mech grip on Snowglade grew so tight.

  Killeen ordered some fresh squads to inspect the storage bay and estimate the carrying capacity of the Flitters. The Family had explored only a fraction of the station, so it was no surprise that this storage-and-receiving bay had eluded them. Killeen had hoped such a place might turn up; the incoming vessel had simply pointed the way.

  A signal came on comm from Shibo.—Something’s happening with the hoop.—

  Killeen quickly made his way through shafts and tunnels to the station’s disk surface. He had to juggle his elation at finding shuttle ships which could take parties to the planet surface, against the unyielding fact that something vast was at work on New Bishop.

  The vision that confronted him was mystifying. The hoop had nearly reached the polar axis, he saw. But it was not moving inward now. Instead, it seemed to turn as he watched. Its inward edge, razor-sharp and now ruler-straight, was cutting around the planet’s axis of ro
tation. In a simulation provided by Shibo he saw the hoop spinning about its flattened edge.

  —It slowed its approach to the axis,—Shibo sent.—Then started revolving.—

  “Looks like getting faster,” Killeen said.

  A pause.—Yeasay…the magnetic fields are stronger now, too.—

  “Look, it’s slicing around the axis.”

  —Like cutting the core from an apple.—

  “Revolving…”

  —Yeasay. Picking up speed.—

  As he watched, the hoop revolved completely around the axis of New Bishop. The golden glow brightened further as if the thing was gaining energy.

  “Pretty damn fast,” Killeen said uselessly, wrestling to see what purpose such gigantic movements could have.

  The simulation grew more detailed as Shibo’s uncanny sympathy with Argo’s computers brought up more information.

  He said quizzically, “That dashed line further out—”

  —That’s this station. We’re clear of the string,—Shibo sent.

  “More like a cosmic ring,” he mused. Wedding band, he thought. Getting married to a planet…“It hitting anything?”

  —Naysay. Nothing’s orbiting near it.—

  “Looks like somethin’ in high polar orbits.” He had picked up some of the jargon from his Aspects but still had trouble with two-dimensional pictures like this simulation.

  —That’s small stuff. Too far away to tell.—

  “Much around the middle?”

  —The equator? More small things. And a funny signal. Looks very large one moment, then a little later it reads as small.—

  “Where?”

  —Close in. Just skims above the atmosphere, looks like.—

  “Sounds like mechtech. We’ve poked our hands into a beehive. Damn!”

  —There’s more. I’ve been scanning New Bishop. Picking up faint signals that seem human-signified.—

  “People?” Killeen felt a spurt of elemental joy. A human presence in this strange enormity…“Great! Maybe we can still live here.”