Ring

27

The nightfighter — with its fragile cargo of humans, and traveling thirty-five light-years with every hyperdrive jump — arced down toward the disc of the scarred galaxy. Spinner-of-Rope sat in her cage, letting the waldoes run through their program; in the corner of her eye, telltales winked reassuringly.

This galaxy was a broad spiral, with multiple arms tightly wrapped around a compact, glowing core. The star system was a pool of rust red, punctuated with the gleam of novae and supernovae: thus, she saw, the galaxy had not escaped depredation at the hands of the photino birds. And the gleaming disc was disfigured by one stunning feature: a huge gouge of a scar, a channel of dust and glowing star-stuff that cut right across the disc, from rim to core.

Now the nightfighter, flickering through hyperspace, neared the rim of the disc, close to the termination of the scar.

This might have been the original Galaxy of humans, Spinner thought, and she wondered if Louise Armonk was sitting under the skydome over the forest, peering out at this freight of stars. Maybe this nostalgic similarity was the reason Louise and the rest had chosen this particular galaxy, out of hundreds of thousands around the cavity, for a closer study.

Suddenly the plane of the disc loomed up at her — and the nightfighter slid neatly into the notch gouged out of the disc.

“Good navigation, Louise,” she said. “Right down the channel.”

“Well, it wasn’t so hard to hit. The channel is over two thousand light-years wide, and as straight as one of your blowpipes. The channel was cut so recently that the galaxy’s rotation hasn’t had time to distort it too far — although, in another few hundred thousand years there will be barely a trace of this feature left…”

The ’fighter plunged along the gouge, and the view was spectacular. Above her was the gaunt, galaxy-stained sky of the Attractor; below and around her was an open tunnel of stars, hurtling past her. Looking ahead, it seemed she could see all the way to the gleaming core of the galaxy. It was difficult to remember that this neat star-walled valley was no less than fifty thousand light-years long…

At thirty-five light-years a second, the ship would reach the core in under thirty minutes.

Now the ’fighter dived into a bank of opaque dust — and then exploded out again, the stars gleaming crimson and gold in the walls of the galaxy-spanning tunnel.

Spinner punched her fist into her palm and whooped.

She heard Louise laugh. “You’re enjoying the ride, Spinner-of-Rope?”

There were voices behind Louise Armonk. “I see it.” Excited, shouting. “I see it — ”

I see it, too.

Spinner turned in her chair, the restraints riding up awkwardly across her chest. The voice had sounded as if it had come from her left.

It had been the voice of the man from her forest dreams, of course. She almost expected to see that slim, dark form, sitting out there beyond the cage: that sixty-year-old face, the hair of gray pepper-speckled with black, the vulnerable brown eyes…

Somehow, she felt he was coming closer to her. He was emerging.

But there was nobody there. She felt disappointed, wistful.

“That was Morrow, butting in,” Louise was saying. “I’m sorry, Spinner. Do you want me to patch you into the conversation?… Spinner? Did you hear me? I said — ”

“I heard you, Louise,” she Said. “I’m sorry. Yes, patch me in, please.”

“…straight ahead of us, at the end of this gouge,” Morrow was saying. “There… there… See?”

“Spinner, I’ll download our visuals to you,” Louise said.

Spinner’s faceplate image was abruptly overlaid with false colors: gaudy reds, yellows and blues, making detail easy to discriminate.

The glowing walls of the star valley dwindled into a dull mist at infinity. And at the end of the valley — almost at the vanishing point itself — there was a structure: a sculpture of thread, colored false blue.

“I see it,” Spinner breathed. Subvocally, she called for magnification.

“Do you know what you’re looking at, Spinner?” Louise’s flat voice contained awe, humility. “It’s what we suspected must have gouged out this valley. It’s a fragment of cosmic string…”

At the center of an immense cavity, walled by crowded galaxies, Lieserl and Mark rotated slowly around each other, warm human planets.

The sky was peppered with the dusty spirals of galaxies, more densely than the stars in the skies of ancient Earth. But the cavity walls were ragged and ill defined, so that it was as if Lieserl was at the center of some immense explosion. And every one of the galaxies was tinged by blue shift: the light from each of these huge, fragile star freights was compressed, visibly, by its billion-year fall into this place.

Mark took her hand. His palm was warm against hers, and when he pulled gently at her arm, her body slowly rotated in space until she faced him.

“I don’t understand,” Lieserl said. “This — cavity — is empty. Where’s the Ring?”

The light of a hundred thousand galaxies, blue-shifted, washed over his face. Mark smiled. “Have patience, Lieserl. Get your bearings first.

“Look around. We’ve arrived at a cavity, almost free of galaxies, ten million light-years across: a cavity right at the site of the Great Attractor. The whole cavity is awash with gravitational radiation. Nothing’s visible, but we know there’s something here, in the cavity… It just isn’t what we expected.”

Lieserl raised her face to stare around the crowded sky, at the galaxies embedded in the walls of this immense cave of sky. One galaxy with an active nucleus — perhaps a Seyfert emitted a long plume of gas from its core; the gas, glowing in the search-light beam of ionizing radiation from the core, trailed behind the infalling galaxy like the tail of some immense comet. And there was a giant elliptical which looked as if it was close to disintegration, rendered unstable by the fall into the Attractor’s monstrous gravity well; she could clearly see the elliptical’s multiple nuclei, orbiting each other within a haze of at least a thousand billion stars.

Some of the galaxies were close enough for her to make out individual stars — great lacy streams of them, in disrupted spiral arms — and, in some places, supernovae glared like diamonds against the paler tapestry of lesser stars. She picked out one barred-spiral with a fat, gleaming nucleus, which trailed its loosening arms like unraveling bandages. And there was a spiral heartbreakingly like her own Galaxy — undergoing a slow, stately collision with a shallow elliptical; the galaxies’ discs had cut across each other, and along the line where they merged exploding stars flared yellow-white, like a wound.

It was, she thought, as if the Universe had been wadded up, compressed into this deep, intense gravity pocket.

Everywhere she caught a sense of motion, of activity: but it was motion on an immense scale, and frozen in time. The galaxies were like huge ships of stars, Lieserl thought, voyaging in toward here, to the center of everything — but they were ships caught suspended by the flashbulb awareness of her own humanity. She longed for the atemporal perspective of a god, so that she could run this immense, trapped diorama forward in time.

“It’s all very beautiful,” she said. “But it almost looks artificial — like a planetarium display.”

Mark grunted. “More like a display of trapped insects. Moths, maybe, drawn in to an invisible gravitational flame. We’re still sifting through the data we’re gathering,” he said softly. “I wonder if any astronomers in human history have ever had such a rich sky to study… even if it does mark the end of time.

“But we’ve found one anomaly, Lieserl.”

“An anomaly? Where?”

He raised his arm and pointed, toward an anonymous-looking patch of sky across the cavity. “Over there. A source in the hydrogen radio band. As far as we can tell it’s coming from a neutron star system — but the neutron star is moving with an immense velocity, not far below lightspeed. Anomalies all round, right? The source is difficult to pick out against all this galactic mush in the foreground. But it’s undoubtedly there…”

“What’s so special about it?”

He hesitated. “Lieserl, it seems to be a signal.”

“A signal? From who?”

“How should I know?”

“Maybe it’s a freak; an artifact of our instruments.”

“Quite possibly. But we’re thinking of checking it out anyway. It’s only a million light-years away.” He smiled ruefully. “That’s all of eight hours’ travel, if you hitch a ride on a nightfighter…”

A signal, here at the end of space and time… Was it possible the motley crew of the Northern wasn’t alone after all?

The hair at the base of her skull prickled. At the end of this long, long life, she’d thought there was nothing left to surprise her.

Evidently, she was wrong.

Mark said, “Lieserl, what you’re looking at here is visible light: the Virtual display we’re drifting around inside is based on images from right at the center of the human visible spectrum. You’re seeing just what any of the others would see, with their unaided vision. But the image has been enhanced by blue shift: red, dim stars have been made to look blue and bright.”

“I understand.”

Now the blue stain faded from the galaxy images, seeping out like some poor dye.

A new color flooded the galaxy remnants, but it was the color of decay dominated by flaring reds and crimsons, though punctuated in places by the glaring blue-white of supernovae. And without the enhancement offered by the blue shift, some of the galaxies faded from her view altogether.

The galaxies had turned into ships of fire, she thought.

Mark’s profile was picked out, now, in colors of blood. “Take a good look around, Lieserl,” he said grimly. “I’ve adjusted out the blue shift; this is how things really are.”

She looked at him curiously; his tone had become hostile, suddenly. Though he still held her hand, his fingers felt stiff around hers, like a cage. “What are you saying?”

“Here’s the result of the handiwork of your photino bird pets,” he said. “In the week since we arrived, we’ve been able to catalog over a million galaxies, surrounding this cavity. In every one of those million we see stars being pushed off the Main Sequence, either explosively as a nova or supernova or via expansion into the red-giant cycle. Everywhere the stars are close to the end of their lifecycles — and, what’s worse, there’s no sign of new star formation, anywhere.”

Suddenly she understood. “Ah. This is why you’ve set up this display for me. You’re testing me, aren’t you?” She felt anger build, deep in her belly. “You want to know how all this makes me feel. Even now — even after we’ve been so close — you’re still not sure if I’m fully human.”

He grinned, his red-lit teeth like drops of blood in his mouth. “You have to admit you’ve had a pretty unusual life history, Lieserl. I’m not sure if any of us can empathize with you.”

“Then,” she snapped, “maybe you should damn well try. Maybe that’s been the trouble with most of human history. Look at all this: we’re witnessing, here, the death of galaxies. And you’re wondering how it makes me feel? Do you think all this has somehow been set up as a test of my loyalty to the human race?”

“Lieserl — ”

“I’ll tell you how I feel. I feel we need a sense of perspective here, Mark. So what if this — this cosmic discontinuity — is inconvenient for the likes of you and me?” She withdrew from him and straightened her back. “Mark, this is the greatest feat of cosmic engineering our poor Universe will ever see — the most significant event since the Big Bang. Maybe it’s time we humans abandoned our species-specific chauvinism — our petty outrage that the Universe has unfolded in a way that doesn’t suit us.”

He was smiling at her. “Quite a speech.”

She punched him, reasonably gently, beneath the ribs, relishing the way her fist sank into his flesh. “Well, you deserve it, damn it.”

“I didn’t mean to imply — ”

“Yes, you did,” she said sharply. “Well, I’m sorry if I’ve failed your test, Mark. Look, you and I — by hook or by crook — have survived the decline and destruction of our species. I know we’re going to have to fight for survival, and I’ll be fighting right alongside you, as best I can. But that doesn’t remove the magnificence of this cosmic engineering — any more than an ant-hill’s destruction to make way for the building of a cathedral would despoil the grandeur of the result.”

Still holding her hand within his stiff fingers, he turned his face to the galaxy-stained sky. His offense at her words was tangible; he must be devoting a great deal of processing power to this sullen rebuke. “Sometimes you’re damn cold, Lieserl.”

Lethe, she thought. People. “No,” she said. “I just have a longer perspective than you.” She sighed. “Oh, come on, Mark. Show me the Ring,” she said.

The sculpture of string, driving itself into the heart of the scarred galaxy, was not symmetrical. It was in the form of a rough figure-of-eight; but each lobe of the figure was overlaid with more complex waveforms — a series of ripples, culminating in sharp, pointed cusps.

“Do you see it, Spinner?” Mark asked. “That is a loop of string nearly a thousand light-years wide.”

Spinner smiled. “That’s not a loop. That’s a knot.”

“It’s moving toward the galactic core at over half the speed of light. It’s got the mass of a hundred billion stars… Can you believe that? It’s as massive as a medium-size galaxy itself. No wonder it’s cutting this swathe through the stars; the damn thing’s like a scythe, driving across the face of this galaxy.”

Louise laughed. “A knot. Knot-making is a skill, up there in the forest, isn’t it, Spinner? I’ll bet you’d have been proud to come up with a structure like that.”

“Actually,” Mark said, “and I hate to be pedantic, but that isn’t a knot, topologically speaking. If you could somehow stretch it out — straighten up the cusps and curves — you’d find it would deform into a simple loop. A circle.”

Spinner heard Garry Uvarov’s rasp. “And I hate to be a pedant, in my turn, but in fact a simple closed loop is a knot — called the trivial knot by topologists.”

“Thank you, Doctor,” Louise said drily.

Spinner frowned, peering at the detailed image of the string loop; in the false colors of her faceplate it was a tracery of blue, frozen against the remote background of the galaxy core. She realized now that she was looking at one projection of a complex three-dimensional object. Subvocally she called for a depth enhancement and change in perspective.

The loop seemed to loom toward her, lifting away from the starry background, and the string was thickened into a three-dimensional tubing, so that she could see shadows where one strand overlaid another.

The image rotated. It was like a sculpture of hosepipe, rolling over on itself.

Mark commented, “But the string isn’t stationary, of course. I mean, the whole loop is cutting through this galaxy at more than half lightspeed — but in addition the structure is in constant, complex motion. Cosmic string is under enormous tension — a tension that increases with curvature — and so those loops and cusps you see are struggling to straighten themselves out, all the time. Most of the length of the string is moving at close to lightspeed — indeed, the cusps are moving at lightspeed.”

“Absurd,” Spinner heard Uvarov growl. “Nothing material can reach lightspeed.”

“True,” Mark said patiently, “but cosmic string isn’t truly material, in that sense, Uvarov. Remember, it’s a defect in spacetime… a flaw.”

Spinner watched the beautiful, sparkling construct turn over and over. It was like some intricate piece of jewelry, a filigree of glass, perhaps. How could something as complex, as real as this, be made of nothing but spacetime?

“I can’t see it move,” she said slowly.

“What was that, Spinner?”

“Mark, if the string is moving at close to lightspeed — how come I can’t see it? The thing should be writhing like some immense snake…”

“You’re forgetting the scale, Spinner-of-Rope,” Mark said gently. “That loop is over a thousand light-years across. It would take a millennium for a strand of string to move across the diameter of the loop. Spinner, it is writhing through space, just as you say, but on timescales far beyond yours or mine…

“But watch this.”

Suddenly the three-dimensional image of the string came to life. It twisted, its curves straightening or bunching into cusps, lengths of the string twisting over and around each other.

Mark said, “This is the true motion of the string, projected from the velocity distribution along its length. The motion is actually periodic… It resumes the same form every twenty thousand years or so. This graphic is running at billions of times true speed, of course — the twenty millennia period is being covered in around five minutes.

“But the graphic is enough to show you an important feature of this motion. It’s non-intersecting… The string is not cutting itself at any point in the periodic trajectory. If it did, it would bud off smaller sub-loops, which would oscillate and cut themselves up further, and so on… the string would rapidly decay, shrivelling through a thousand cuts, and leaking away its energy through gravitational radiation.”

Spinner wished, suddenly, that she wasn’t human: that she could watch the motion of this loop unfold, without having to rely on Mark’s gaudy projections. How wonderful it would be to be able to step out of time!

…Close your eyes, Spinner.

“What?”

You can step out of time, just as you desire. Close your eyes, and imagine you are a god.

…And here, in her mind’s eye — so much more dramatic than any Virtual! — came the knot of string, sailing out of space. The knot wriggled like some huge worm, closed on itself as if swallowing its own tail.

The knot struck the rim of this defenseless galaxy and scythed toward the core, battering stars aside like blades of grass.

It was a disturbing, astonishing image. She snapped open her eyes, dispelling the vision; fear flooded her, prickling over her flesh.

She wasn’t normally quite so imaginative, she thought drily. Maybe her companion had had something to do with that brief, vivid vision…

She returned her attention to the harmless-looking Virtual display. Now Mark showed Spinner the loop’s induced magnetic field, a yellow glow of energy which sleeved the fake blue of the string itself.

“As it hauls through the galaxy’s magnetic field, that string is radiating a lot of electromagnetic energy,” Mark said. “I see a flood of high-energy photons…”

Cosmic string wasn’t actually one-dimensional; it was a Planck length across, a fine tube containing charged particles: quarks, electrons and their antiparticles, gathered into super-heavy clusters. As a result, string acted as a superconducting wire.

The string knot was cutting through this galaxy’s magnetic field. As it did so immense electrical currents — of a hundred billion billion amps or more — were induced in the string. These currents generated strong magnetic fields around the string.

The string’s induced field was stronger than a neutron star’s, and dominated space for tens of light-years around the knot.

Mark said, “The string has a maximum current capacity. If it’s overloaded, the string starts to shed energy. It glows with gamma radiation. And the lost energy crystallizes into matter: ions and electrons, whispering into existence all along the length of the string.” Spinner saw representations of particles — out of scale, of course — popping into existence around the string image. “So the string is glowing as brightly as a star.”

“Yes,” Louise put in. “But the distribution of the radiation is odd, Mark. Look at this. The radiation is beamed forward of the loop’s motion — parallel to that forward spike of gravitational radiation.”

“Like a searchlight,” Morrow said.

Or a spear…

She heard Morrow saying, “Mark, what is driving the string? What is impelling it through space, and into this galaxy?”

“Gravitational radiation,” Mark said simply.

Louise said, “Morrow, gravity waves are emitted whenever large masses are moved through space. Because the loop is asymmetrical it’s pushing out its gravitational radiation in particular directions — in spikes, ahead of and behind it. It is pushing out momentum… It is a gravitational rocket, using its radiation to drive through space.”

Mark said, “Of course the gravitational radiation is carrying away energy — the string is shrinking, slowly. In the end it will collapse to nothing.”

“But not fast enough to save this galaxy,” Uvarov growled.

“No,” Louise said. “Before it has time to decay away, the string is going to reach the core — and devastate the galaxy.”

Close your eyes.

Spinner-of-Rope shivered. Once again the voice had come from her left — from somewhere outside her suit. She stared at the Virtual image in her faceplate, not daring to look around.

Close your eyes. Think about your vision again — of the string loop, cutting through the stars. It frightened you, didn’t it? What did that image mean, Spinner-of-Rope? What was it telling you?

Suddenly she saw it.

“Mark,” she said. “This is not just a gravitational rocket.”

“What?”

“Think about it. The string knot must be a missile.”

The galaxy images dimmed, leaving Mark and Lieserl suspended in a crimson-tinged darkness. Then, against that background, new forms began to appear: speckles of light, indistinct, making up the ghostly outline of a torus, its face tipped open toward her.

“Of course this is a false color representation,” Mark said. “The images have been reconstructed from gravity wave and gamma ray emissions…”

The torus as a whole reminded her, distantly, of Saturn’s rings; it was a circle which spanned the galaxy-walled cavity.

At first she thought the component speckles were mere points of light: they were like stars, she thought, or diamonds scattered against the velvet backdrop of the faded galaxy light. But as she looked more closely she could see that some of the nearer objects were not simple points, but showed structure of some kind.

So these weren’t stars, she thought, and nor was this some attenuated galaxy: there were only (she estimated quickly) a few thousand of the shining forms, as opposed to the billions of stars in a galaxy… And besides, this cavity spanning torus was immense: she could see how the blood-dark corpses of galaxies sailed through its sparse structure.

She knew that the Galaxy of humans had been a disc of stars a hundred thousand light-years in diameter. This torus must be at least a hundred times as broad — more than ten million light-years across.

She turned to Mark; he studied her face, a certain kindness showing in his eyes now. “I know how you’re feeling. It’s magnificent, isn’t it?”

“It can’t be the Ring,” she said slowly. “Can it? As far as we know, Jim Bolder reported a solid object — a single, continuous artifact.”

“Look more closely, Lieserl. Cheat a little; enhance your vision. What do you see?”

She turned her head and issued brisk subvocals. A section of the torus exploded toward her; the fragments, rushing apart, gave her a brief, disorienting impression of sudden velocity.

Her view steadied. Now, it was as if she was within the torus itself, and the sparkling component objects were all around her.

The fragments weren’t simple discs — or ellipses, or any of the shapes into which a star or galaxy might be distorted by the presence of others. She could see darkness within the heart of these objects.

The fragments were knots.

“Mark — ”

“You’re looking at loops of cosmic string,” he said calmly. “This immense torus is made up of string knots, Lieserl ten thousand of them, each a thousand light years across.”

She was aware of her hand convulsing closed around his. “I don’t understand. This is — fantastic. But it isn’t the Ring Bolder described.”

He looked distant, wistful. “But it must be. We know we’ve come to the right place, Lieserl. This is undoubtedly the site of the Great Attractor: the loops, together, have sufficient mass to cause the local streaming of galaxies.

“And we know this assemblage must be artificial. Primeval string loops could have formed during the formation of the Universe, after the singularity. But there should have been no more than a million of them — in the entire Universe, Lieserl — spaced tens of millions of light-years apart. It simply isn’t possible for a collection of ten thousand of the damn things to have gathered spontaneously within a cavity a mere ten million light-years across…”

“But,” Lieserl said patiently, “but Bolder said the Ring was solid. If he was right — ”

“If he was right then the Ring has been destroyed, Lieserl. These loops are rubble. We’re looking at the wreckage of the Ring. The photino birds have won.” He turned to her, his face a sculpture, expressionless, obviously artificial. “We’re too late, Lieserl.”

She felt bewildered. “But if that’s true — where are we to go?”

Mark had no answer.

Louise said, “What are you talking about, Spinner?”

“Can’t you see it?” She closed her eyes and watched, once again, as the string loop punched through the fragile superstructure of the galaxy. “Mark — Louise this string loop was aimed, quite precisely. It’s a weapon. It is blasting through this galaxy with its gravitational rockets, destroying all in its path with focused beams of electromagnetic and gravitational energy…”

Louise snapped, “Mark?”

Mark hesitated. “We can’t prove she’s right, Louise. But the chances of the loop hitting such a precise trajectory at random are tiny…”

“It seems crazy,” Morrow said. “Who would dare use a thousand-light-year loop of cosmic string as a weapon of war?”

Uvarov grunted. “Isn’t that obvious? The very entities we have come all this way to seek, from whom we hope to obtain shelter — the Xeelee, Morrow; the baryonic lords.”

“But why?” Mark asked. “Why destroy a galaxy like this?”

“In defense,” Uvarov snapped.

“What?”

“Isn’t that clear too? The Xeelee were masters of the manipulation of spacetime. Their weaponry consisted of these immense structures of spacetime flaws. And the flaws have been used against the weapons of their enemies — like this galaxy.”

There was silence for a moment. Then Morrow said, “Are you insane, Uvarov? You’re saying that this galaxy has been hurled like some rock — deliberately?”

“Why not?” Uvarov replied calmly. “The photino birds are creatures of dark matter — which attracts baryonic matter gravitationally. We can easily imagine some immense dark chariot hauling at this fragile galaxy, hurling it hard through space…

“Think of it. The photino birds must have begun to engineer the deflection of this galaxy’s path many millions of years ago — perhaps they were intent on launching this huge missile at the Ring long before men walked on the Earth. And the Xeelee must have been preparing their counter, this loop of string, over almost as great a timescale.”

Now Spinner-of-Rope felt a bubble of laughter, wild, rise in her own throat. She had an absurd image of two giants, bestriding the curving Universe, hurling galaxies and string loops at each other like lumps of mud.

“We are truly in the middle of a war zone,” Uvarov said coldly. “This galaxy, with the bullet of cosmic string aimed so accurately at its heart, is merely one incident among ten million in a huge battlefield. To our fleeting perceptions the field is frozen in time — we buzz like flies around the bullet as it hurtles into the chest of its target — and yet the battle rages all around us.”

Don’t be afraid.

Spinner closed her eyes and thought of the forest dream man, smiling at her from his tree and eating his fruit…

I know who this is, she realized suddenly. I’ve seen his face, in Louise’s old Virtuals…

“I know you,” she told him.

Yes. Don’t be afraid, said Michael Poole.

28

Louise Armonk asked Spinner to take the nightfighter to the source of Mark’s anomalous hydrogen-band signal.

She showed Spinner some data on the signal. “Here’s a graphic of the main sequence, Spinner-of-Rope.” A bar-chart, in gaudy yellow and blue, marched across Spinner’s faceplate. “We’re getting pretty excited about this. For one thing it’s periodic — the same pattern recurs every two hours or so. So we’re pretty sure it has to be artificial. And look at this,” Louise said. A sequence of thirty bars, buried among the rest, was now highlighted with electric blue. “Can you see that?”

Spinner looked at the ascending sequence of bars, trying hard to share Louise’s excitement. “What am I looking for, Louise?”

She heard Louise growl with impatience. “Spinner, the amplitude of these pulses is increasing, in proportion with the first thirty prime numbers.”

The electric-blue bars were split into discrete blocks, now, to help Spinner see the pattern. She counted the blocks: one, two, three, five, seven…

She sensed an invisible smile. Just like a child’s puzzle, isn’t it?

“Oh, shut up,” she said easily.

“What was that?”

“Nothing… I’m sorry, Louise. Yes, I see it now.”

“Look what’s exciting about finding this sequence of primes is that it means the signal is almost certainly human.”

“How do you know that, just from this pattern?”

“We don’t know for sure, of course,” Louise said impatiently. “But it’s a damn good clue, Spinner-of Rope. We’ve reason to believe the prime numbers are of unique significance to humans.

“The primes are fundamental structures of arithmetic — at least, of the discrete arithmetic which seems to come naturally to humans. We are compact, discrete creatures: I’m here, you are out there somewhere. One, two. Counting like this seems to be natural to us, and so we tend to think it’s a fundamental facet of the Universe. But it’s possible to imagine other types of mathematics.

“What of creatures like the Qax, who were diffuse creatures, with no precise boundaries between individuals? What of the Squeem, with their group minds? Why should simple counting be natural to them? Perhaps their earliest forms of mathematics were continuous — or perhaps the study of infinities came naturally to them, as naturally as arithmetic to humans. With us, Cantor’s hierarchy of infinities was quite a late development. And — ”

Spinner barely listened. Humans? Here, at the edge of time and space? “Louise, have you decoded any of the rest of it?”

“Well, we can figure some of it out,” Louise said defensively. “We think, anyway. But remember, Spinner, we may be dealing with humans from a culture far removed in time from our own — by millions of years, perhaps. The people of such a distant future could be almost as remote from us as an alien species. Not even Lieserl has been able to help us work this out…

“But you’ve made some progress. Right?”

Louise hesitated. “Yes. We think it’s a distress call.”

“Oh, great. Well, we’re certainly in a position to help out god-humans from five million years after our birth.”

“Who knows?” Louise said drily. “Maybe we are. Anyway, that’s what we’re going to find out.”

…There was motion at Spinner’s left. She turned.

Suddenly, the forest-dream man was visible. He was sitting there, quite casually — outside the cage — on the construction-material shoulder of the nightfighter. He wore no environment suit, nothing but a plain gray coverall. His hands were folded in his lap. Light — from some unseen source — caught the lines around his mouth, the marks of tiredness in his eyes.

At last he had emerged. Gently, he nodded to her.

She smiled.

“…Spinner?”

“I’m here, Louise.” She tried to focus her attention on her tasks; she reached for the hyperdrive waldo. “Are you ready?”

“Yes.”

The nightfighter flickered through hyperspace. Traveling at more than a hundred thousand light-years per hour, the Northern edged around the torus of fragmented string loops, like a fly around the rim of a desert.

The journey took ten hours. As it neared its end Spinner-of Rope took a brief nap; when she woke, she had her suit’s systems freshen her skin, and she emptied her bladder.

She checked a display on her faceplate. Twenty jumps to go. Twenty more seconds, and -

Something vibrant-blue exploded out of space at her, ballooning into her face.

She cried out and buried her faceplate in her arms.

It’s all right, Poole said softly.

“I’m sorry, Spinner-of-Rope,” Louise Armonk said. “I should have warned you…”

Spinner lowered her arms, cautiously.

There was string, everywhere.

A tangle of cosmic string, rendered electric blue by the faceplate’s false coloring, lay directly ahead of the ship. Cusps, moving at lightspeed, glittered along the twisted lengths. She leaned forward and looked up and down, to left and right; the threads of string criss-crossed the sky as far as she could see, a textured wall across space. Looking deeper into the immense structure. Spinner saw how the individual threads blurred together, merging into a soft mist at infinity.

The string loop was a barrier across the sky, dividing the Universe in two. It was quite beautiful, she thought — but deadly. It was a cosmic web, with threads long enough to span the distances between stars: a web, ready to trap her and her ship.

And, she knew, this was just one thousand-light-year fragment, among thousands in the torus…

“Lethe,” she said. “We’re almost inside this damn thing.”

“Not quite,” Louise said. Her voice, nevertheless, was tight, betraying her own nervousness. “Remember your distance scales, Spinner. The string loops in this toroidal system are around a thousand light-years across. We’re as far from the edge of that loop as the Sun was from the nearest star.”

“Except,” Mark Wu cut in, “that the loop has no easily definable edge. It’s a tangle. Cosmic string is damn hard to detect; the display you’re looking at, Spinner, is all Virtual reconstruction; it’s just our best guess at what lies out there.”

“Then are we at risk by being here?” Spinner asked.

Of course, Michael Poole said.

“No,” Louise said.

“Yes,” Mark said. “Come on, Louise. Spinner, we’re working to minimize the risks. But the danger is there. Spinner, you need to be ready to react — to get us out of here, quickly. We have escape routines laid into the waldoes, for both hyperdrive and discontinuity drive.”

“I’ll be ready,” she said calmly. “But why are we here? Is the human signal coming from somewhere in there — inside the string?”

“No,” Louise said. “Thankfully, Spinner, the signal is coming from the system of a neutron star — just a few light hours away from here. We’ve laid in — ”

” — a discontinuity-drive sequence into the waldoes,” Spinner said drily. “I know.” She reached for her controls. “Tell me when you’re ready, Louise.”

Poole looked tired, his brown eyes deep in a mesh of wrinkles. You know, I worked with Louise Armonk, he said. He smiled. And here we are, together again. Small world, isn’t it? She was a good engineer. I guess she still is.

“I know you decided to close your wormhole time bridge,” Spinner said. “Tell me what happened to you.”

Poole sat, apparently relaxed, on the ’fighter shoulder; his eyes were closed, his head bent forward. I remember the lifedome of my GUTship entering the Interface, he said slowly. There was light — like fire, blue-violet — from all around the lip of the dome. I knew that was the flesh of the Spline, burning up against the Interface’s exotic-matter framework. I remember — a sense of loss, of alienation.

“Loss?”

I was passing out of my time frame. Spinner-of-Rope, each of us — (he raised translucent hands) — even I — is bound into the world by quantum functions. I was linked non-locally to everything I had touched, seen, tasted… Now, all those quantum bonds were broken. I was as alone as any human had ever been.

I engaged the hyperdrive.

Bits of the wormhole seemed to fall away. I remember streams of blue-white light… I almost believed I could feel those hard photons, sleeting through the lifedome.

Spacetime is riddled with wormholes: it is like a sheet of flawed glass, crazed by cracks. When Poole set off his hyperdrive inside the wormhole, it was as if someone had smashed at that flawed glass with a hammer. Cracks exploded out from the point of impact and widened; they joined up in a complex, spreading network of cracks, a tributary pattern that continually formed and reformed as spacetime healed and shattered anew.

The spacetime cracks opened up like branching tunnels, leading off to infinity… Poole smiled, self-deprecating. I started to wonder if this had been a good plan, after all.

The pod sailed down from the Northern’s lifedome.

Lieserl sat in a Virtual projection of a pod couch beside Mark Wu; ahead of them blind Uvarov was swathed in his blankets, his cavern of a mouth gaping, his breath a rattle. The huge discontinuity-drive wings of the nightfighter spread over the pod like the vaulted roof of some immense church.

Far below the pod revolved the bleak, airless planet to which they were descending. Staring down as the small island of solidity loomed out of the glowing fog, Lieserl had a sudden — and quite absurd — feeling of vertigo. She felt as if she were suspended, in this couch, without protection far above the planet’s surface; she had an impulse, which she suppressed with determination, to grip the sides of her couch.

Vertigo… After all her experiences inside the Sun, and despite her perfect knowledge that she couldn’t be harmed even if the pod exploded here and now since she was little more than a Virtual projection from the Northern’s main processors, with augmentation from the pod’s processor banks — after all that, she had vertigo.

Still, she thought, it was comforting to know that she’d retained enough humanity to be just a little scared. Maybe she should tell Mark; it might make him think a little better of her.

Beyond the pod’s clear hull, the neutron star system was a huge tableau all around them.

The neutron star itself was a tiny, fierce yellow-red ball. It had a companion a normal star — and it was surrounded by a ring of gas, which glowed softly. And there were several planets, orbiting the neutron star, inside the smoke ring.

In fact, the anomalous signal was coming from one of the planets, the little world toward which Lieserl was now descending.

The nightfighter had dropped them into the ring of smoke which orbited the star. It was like descending into fog. Close to the pod Lieserl could see dense swirls of the ring gas — clumps and eddies of turbulent stuff — and, beyond that, the rest of the ring was a band of pale light bisecting the Universe. She could see the neutron star itself, a small, hard coal glowing yellow-red at the heart of this ring of smoke. Beside it hung its companion star huge, pale, distorted into a squat egg-shape by the neutron star’s fierce gravitational field. Tendrils of gas led from the carcass of the companion and reached blindly toward the neutron star.

And beyond that, tilted crazily compared to the gas torus, was a starbow.

This neutron star was moving with extraordinary speed: it plummeted across space at close to the speed of light. As a result of this high velocity, the neutron star and its system were the only visible objects in Lieserl’s Universe. All of the rest — the blue-shifted galaxies, the nearby wall of cosmic string — was compressed into that pale starbow, a band of light around the equator of the star’s motion. And away from the starbow, there was only darkness.

Uvarov tilted his head, and the pod’s internal lights cast shadows across his imploded eye-sockets. “Tell me what you see,” he hissed.

“I see a neutron star,” Mark said. “An unexceptional member of its species. Just ten miles across, but with a mass not much less than Sol’s… What has made this one unusual is the fact that it has a companion, which is — was — a normal star.”

Before Mark, a Virtual diorama of the neutron star system glittered into existence; the globes of the neutron star and its companion were criss-crossed by lines of false color, showing — Lieserl suspected — gravitational gradients, lines of magnetic flux, and other observables. Bits of text and subsidiary graphics drifted in the air beside the glowing objects.

“Once,” Mark said, “these stars were a binary pair — a spectacular one, since the neutron star must have been a brilliant giant. Somehow, the companion survived the giant’s supernova explosion. But the remnant of that explosion the neutron star — is killing its companion, just the same.” He pointed. “The neutron star’s gravity well is sucking out material from the companion… Look at it, Lieserl; those delicate-looking tendrils of smoke could swallow Jupiter. Some of the companion’s lost matter is falling onto the neutron star itself. And as the mass down there increases, the rotation of the neutron star will glitch — the neutron star must suffer starquakes, quite regularly. The rest of the gas is drifting off to form this ring we’re in, orbiting the neutron star.”

“Do you think the birds caused the supernova explosion, Mark?” Lieserl asked.

He shook his head. “No. The system is too stable… I think the explosion took place long before the birds took an interest.”

“And the companion?”

He smiled, peering up at the complex sky. “Lieserl, that is one star the birds don’t need to kill. The neutron star is doing their work for them.”

The Virtual representation of the neutron star expanded before his face, expelling the companion and the other features from the diorama. Mark peered into a complex knot of light at what looked like one of the star’s magnetic poles.

Lieserl looked away. The planet wasn’t far below, now; slowly it was turning from a ball of rock, suspended in emptiness, into a landscape — bare, bleak, riven by cracks.

“What about the planets?” Lieserl asked. “How could they have survived the supernova?”

“My guess is they didn’t,” Mark said, still staring at the star’s pole. “I think they probably formed after the explosion: coalesced from material in the gas ring, and from debris left over from the explosion itself — maybe from the previous planetary system, if there was one… Lieserl. Lethe. Look at this.”

“What?”

The neutron star Virtual representation swept across the cabin toward her; the little knot of light at the pole was thrust in her face. Lieserl flinched, but stared gamely into the glowing, complex image.

Mark was grinning, his voice animated by excitement. “Do you see it?”

“Yes, Mark,” she said patiently, “but you’re going to have to tell me what I’m seeing.”

“There’s a major disturbance in the gravitational gradients at that magnetic pole.” Arrows clustered around the star’s pole, forming themselves into a two dimensional plane. “Can you see it?”

“What about it?”

Mark sounded impatient. “Lieserl, I think there’s a sheet discontinuity down there. A two-dimensional defect. A domain wall, inside the star…”

Lieserl frowned. “That’s impossible.”

“Of course it is.” He grinned. “How could a domain-wall defect form within the structure of a neutron star? Impossible… unless it’s been put there.”

Uvarov’s ruined mouth stretched into a smile. “Put there?”

“We wondered how come this neutron star was out here on its own — away from any galaxy, and moving so bloody fast. Well, now we know.”

Lieserl found herself laughing. “This is outrageous. Are you suggesting — ”

“Yes,” he said seriously. “I think someone, maybe human, installed a discontinuity drive at the magnetic pole of this neutron star, and used it to hurl the whole system across space at close to lightspeed.”

“But that’s absurd,” she said. “Why should anyone do such a thing?”

Now Uvarov laughed, at her. “Still the rationalist, Lieserl, after all our experiences? Well, perhaps we will soon learn the answer to such questions. But of this I’m sure — that it has some connection to this endless, bloody war in Heaven we’ve wandered into.”

The pod’s descent bottomed out, now, and the little ship sailed over the planet’s battered landscape.

At length, Mark said, “We’re over the source of the signals… There,” he said suddenly. “Can you see it?”

Uvarov tilted his head on its thin neck.

Lieserl peered down.

“A structure,” Mark said. “There on the surface… Some kind of building. Come on; I’ll take us down.”

I fell into the future, Spinner-of-Rope, through a network of transient wormholes that collapsed after me. My instruments were smashed, but I knew my lifedome must have been awash with high-energy particles and gravity waves. I was as helpless as a new-born babe.

Poole sat in raw vacuum on the shoulder of the nightfighter with his legs tucked beneath him, lotus-style, his hands resting comfortably, palms-up, on his knees. Spinner could see a grooved pattern, molded mundanely into the soles of his shoes.

He said, I fell across five million years…

Mark Wu — or rather, one of his Virtual consciousness foci, on the Northern — peered at the loop of cosmic string through the hundred eyes of the ship’s sensors. He wasn’t happy: his multifaceted view was muddy, imprecise.

The trouble was, the ship was in orbit around this damn neutron star planet, which was falling through space so fast the observable Universe was relativity shifted into a skinny, pale starbow. It was like being taken back to the Northern’s thousand-year flight. Mark had to deconvolve out the effects of the near-lightspeed motion: to unsmear the Universe back out of the starbow once more.

Mark had subroutines to achieve this. But it was, he thought uneasily, a little like unscrambling an egg. The resulting images weren’t exactly clear.

Inside his box of processors, Mark Wu worked on nanosecond timescales. He could process data at several millions of times the rate achievable by humans, and it sometimes took an effort of will to come back out of there and return to the glutinous slowness of the human world.

It was seven centuries since his physical death and downloading into the AI banks of the Northern, and he’d steadily got more proficient at non-human operation. Right now, for instance, he was maintaining a conventional human Virtual on the pod with Lieserl and Uvarov, and another with Louise in the Great Britain, in parallel with his direct interfacing with the Northern’s systems.

Running these multiple consciousness foci felt odd, but he’d grown used to enduring minor discomforts when the need arose.

And there was need now.

Maybe he should have tried to veto this trip to the neutron star, he thought. It had brought the Northern close — too damn close — to this loop-cloud of cosmic string. When dealing with an object a thousand light-years across, he thought sourly, a separation of a mere handful of light years didn’t seem nearly sufficient.

Mark split off a series of more subordinate foci, and set to scanning overlapping sectors of the sky.

His image of the Universe was a mosaic, constructed of the fragments supplied to him by the sensors; he imagined it was a little like looking out through the multifaceted eyes of a fly. And the Universe was criss-crossed, everywhere, by string double-image paths — it was as if the sky were some huge dome of glass, he thought, marred by huge cracks.

By studying the double images of stars and galaxies, Mark was able to check on the near-lightspeed velocities of the string segments; he constantly updated the internal model he maintained of the local string dynamics, trying to ensure the ship stayed a safe distance away from -

A watchful subroutine sounded an alarm. It felt to Mark like a prickling of vague unease, a shiver.

…There was movement, in the field of view of one sensor bank. He swiveled his consciousness, fixing most of his attention on the anomaly picked up by that sensor bank.

Against a background provided by a beautiful, blue-stained spiral galaxy, he saw a double track of multiple stellar images.

There had to be two lengths of string there, he realized: two arcs of this single, huge loop of string, no more than light-hours apart. And he could see from the melting flow of the star images that the arcs were sliding past each other in opposite directions; maybe eventually they would intersect.

In some places there were three images of single stars. Light from each of those stars was reaching him by three routes — to the left of the string pair, to their right, and straight through the middle of the strings.

The cause of the alert was obvious. All along the double tracks, he saw, star images were sliding, as if slipping across melting spacetime. These strings must be close — maybe even within the two-light-year limit he’d imposed on himself as a rough safety margin.

He ran a quick double-check on the routines he’d set up to monitor the strings’ distance from the ship. He wondered if he ought to tell Louise and Spinner about this…

Now, suddenly, alarm routines shrieked warnings into his awareness. It was like being plunged into an instant panic; he felt as if adrenaline were flooding his system.

What in Lethe —

He interrogated his routines, briskly and concisely. It took only nanoseconds to figure out what was wrong.

The pair of string arcs were closer than he’d thought at first. His distance estimation routines had been thrown by the interaction of the two strings, by the way the pair jointly distorted star images.

So the strings were closer than his monitoring systems had told him. The trouble was, he couldn’t tell how close; maybe they were a lot closer.

Damn, damn. I should have anticipated this. Feverishly he set off a reprogramming routine, ensuring that for the future he wouldn’t be fooled by multiple images from pairs of string lengths like this — or, indeed, from any combination.

But that wasn’t going to help now.

He ran through a quick hack procedure, trying to get a first-cut estimate of the strings’ true distance…

He didn’t believe the answer. He modified the procedure and ran it again.

The answer didn’t change.

Well, so much for my two-light-year safety zone.

The string pair was only around ten million miles from the Northern — less than a light-minute.

One of the pair of strings was receding — but the other was heading straight for the ship.

He ran more checks. There was no error.

In fifty seconds, that encroaching string would hit the Northern.

He burst out of the machinery and back into the world of humans. With impatience he waited for pixels to congeal out of the air, for his face to reassemble; he felt his awareness slow down to the crawl of humans.

29

Five million years after the first conflict between humans and Qax, the wreckage of a Spline warship had emerged, tumbling, from the mouth of a wormhole that blazed with gravitational radiation. The wormhole closed, sparkling.

The wreck — dark, almost bereft of energy — turned slowly in the stillness. It was empty of life.

Almost.

I’m still not sure how I survived. But I remember — I remember how the quantum functions came flooding over me. They were like raindrops; it was as if I could see them, Spinner-of-Rope. It was painful. But it was like being born again. I was restored to time.

It hadn’t taken Poole long to check out the status of the derelict his craft had become. There had been power in the lifedome’s internal cells, sufficient for a few hours, perhaps. But he had no motive power — not even a functioning data link out of the lifedome to the rest of his ship.

I remember how dead the Universe looked. I couldn’t understand how the stars had got so old, so quickly; I knew I couldn’t have fallen more than a few million years.

But I knew I was alone. I could feel it.

I made myself a meal. I drank a glass of clear water… His face, softly translucent, was thoughtful. Do you know, I can remember the taste of that water even now. I had a shower… I was thinking of reading a book.

But the lights went out.

I felt my way back to my couch. I lay there. It started getting colder.

I wasn’t afraid of death, Spinner-of-Rope. Strangely, I felt renewed.

“But you didn’t die,” she said. “Did you, Michael?”

No. No, I didn’t die, said Poole.

And then, a ship had come.

Poole, dying, had stared up in wonder.

It was something like a sycamore seed wrought in jet-black. Night-dark wings that spanned hundreds of miles loomed over the wreck of Poole’s GUTship, softly rippling.

“A nightfighter,” Spinner breathed.

Yes. I got colder. I couldn’t breathe. But now I didn’t want to die. I wanted to live just a little longer — to understand what this meant.

And then —

“Yes?”

And then, something had plucked Poole from the wreck. It was as if a giant hand had cupped his consciousness, like taking a flame from a guttering candle.

And then it spun me out…

Poole had become discorporeal. He no longer even had a heartbeat.

He felt as if he had been released from the cave of bone that had been his head.

I believe I became a construct of quantum functions, he said. A tapestry of acausal and nonlocal effects… I don’t pretend to understand it. And my companion was still there. It was like a huge ceiling over me.

“What was it?”

Perhaps it was Xeelee. Or perhaps not. It seemed to be beyond even the Xeelee a construct by them, perhaps, but not of them…

Spinner-of-Rope, the Xeelee were — are — masters of space and time. I believe they have even traveled back through time — modified their own evolutionary history — to achieve their huge goals. I think my companion was something to do with that program: an anti-Xeelee, perhaps, like an anti particle, moving backwards in time.

I sensed — amusement, Poole said slowly. It was amused by my fear, my wonder, my longing to survive. She heard the faded ghost of bitterness in his voice.

After a time, it dissolved. I was left alone. And, Spinner, I found I could not die.

At first, I was angry. I was in despair. He held up his glowing hand and inspected it thoughtfully, turning it round before his face. I couldn’t understand why this had been done to me — why I’d been preserved in this grotesque way.

But — with time — that passed. And I had time: plenty of it…

He fell silent, and she watched his face. It was blank, expressionless; she felt a prickle of fear, and wondered what experiences he had undergone, alone between the dying stars.

“Michael,” she said gently. “Why did you speak to me?”

His bleak expression dissolved, and he smiled at her. I saw a human being, he said. A man, dressed in skins, frostbitten, in a fragile little ship… He came plunging through a wormhole Interface, uncontrolled, into this hostile future.

It was an extraordinary event… So I — returned. I was curious. I probed at the wormhole links — and found you, Spinner-of-Rope.

Spinner nodded. “He was Arrow Maker. He was my father,” she said.

Michael Poole closed his eyes.

“…Spinner-of-Rope,” Louise Armonk said. She sounded urgent, concerned.

“Yes, Louise.”

“I don’t know what in Lethe is happening in that head of yours, but you’d better get it clear fast.” Spinner heard Louise issue commands over her shoulder. “…We’ve got a problem.”

“What kind of problem?”

“Listen to me, Spinner. Here’s what you must — ”

Louise’s voice died, abruptly.

“Louise? Louise?”

There was only silence.

Spinner twisted in her couch. Behind her, the bulk of the lifedome loomed over the clean lines of the nightfighter, a wall of glass and steady light.

But now a soft webbing, a mesh of barely visible threads, lay over the upper levels of the lifedome.

“Lethe,” Spinner hissed. “That’s string.”

For the first time in several years, the Decks were filled with the wail of the klaxon.

Morrow, hovering in the green-tinged air close to Deck Two, straightened from his work. His back ached pleasurably, and there was warm dirt and water on his hands; he felt a fine slick of sweat on his forehead.

He looked around vaguely, seeking the source of the alarm.

Milpitas, his sleeves rolled up and the deep scars of his face running with sweat, studied him. The Planner fingered a handful of reeds which protruded from the spherical pond. “Morrow? Is something wrong? Why the klaxon?”

“I don’t know, Planner.”

The sound of the klaxon was deafening — at once familiar and jarring, making it hard to think. Morrow looked around the Decks, at the tranquil, three dimensional motion of people and ’bots as they went about their business; in the distance the shoulders of the Temples loomed over the grass-covered surfaces. It all looked normal, placid; he felt relaxed and safe.

Morrow was working with Milpitas within what had once been Poole Park. They were still trying to establish their zero gee water feature. Milpitas and Morrow had set a ball of earth on a fine pole, attached it to the Deck surface, and surrounded it with a globe of water five feet across, restrained by a fine skin of porous plastic. Reeds and lilies were planted in the ball of earth, and were already growing out of the water surface. Their vision was that the reeds and lilies — perhaps plaited in some way — together with the water’s natural surface tension would eventually suffice to hold the pond together, and they could abandon the plastic membrane.

Then, at last, they could populate the pond, with fish and frogs.

It was a small, almost trivial project. But it had actually been Milpitas’ idea, and Morrow had been glad to offer to work on it with him, as part of what he thought of as Milpitas’ rehabilitation to zero-gee. Anything that got the Planner — and those he influenced — thinking and working in zero-gee conditions was a good thing, in Morrow’s view.

“Morrow.” Louise Armonk’s voice emerged from a point in the air. It was loud, urgent in his ear. “Morrow. Can you hear me?”

Morrow looked down to the grass-coated floor of the Deck; he knew that Louise was somewhere below his floor in her old steam-ship, studying the neutron star system. “What is it, Louise?”

“Morrow, you have to get away from there.”

“But, Louise — ”

“Move, damn it. Anywhere.”

Milpitas was studying him. “Well? Is there a problem?”

“Milpitas. Come.”

Morrow grabbed the Planner’s robe at the shoulder. He flexed his knees, planted his feet squarely against the Deck surface, and pushed himself into the air, dragging Milpitas after him. Looking down, he saw the spherical pond recede below them.

Air resistance brought them to a stop in mid-air, five yards above the Deck surface.

Morrow released the Planner. Milpitas’ arms were still wet to the elbow, and his bony legs protruded from beneath his robe.

“Louise? All right, we’ve moved. Now will you tell me what’s wrong?”

“We’re in trouble.” Morrow heard panicky shouting behind Louise’s voice, and flat, even commands being issued by Mark. “We’re in the path of a section of string… If our projections are correct, it’s going to pass right through Poole Park.”

Morrow stared around at the Decks. Suddenly the metal walls of this place, coated with plants and people, seemed impossibly fragile. “But how can that be? I thought that loop was light-years away.”

“So did we, Morrow. We’re trying to confirm the string’s trajectory so we can program the discontinuity-drive waldoes, and — ”

But Louise’s voice was gone.

Lieserl and Mark stood on the surface of the neutron star planet, in Virtual mockups of environment suits. They looked at each other uncertainly.

“Something’s wrong,” Lieserl said.

“I know.” Through his sketch of a faceplate, Mark’s expression was lifeless, cold; Lieserl knew that meant he was diverting processing power to higher priorities.

The surface under Lieserl’s feet was pumice-gray and looked friable. Beside them, waiting patiently, was a ’bot, a fat wheeled trolley fitted with a few articulated arms and sensors. The dust of the planet had smeared the ’bot’s wheels with gray, Lieserl saw.

A few yards away their pod was a fat, gleaming cylinder; within the pod’s clear walls Lieserl could see Uvarov, wrapped in his blanket.

The sky was fantastic. The gas ring was a belt of smoke which encompassed the world, all the way to the horizon. The far side of the ring was a pale strip of white, bisecting the sky. She could just make out the neutron star itself, a tiny, baleful blood-pearl threaded onto the line of smoke; and its huge companion was an attenuated ball of yellow-gray mist, bleeding gas onto its malevolent twin.

The starbow was a crack across the emptiness away from the plane of the ring; high above her head, Lieserl could see the gleaming lights of the Northern’s lifedome, in the ship’s remote orbit around the planet.

The building they had detected from orbit was a tetrahedron, twenty feet tall, sitting impassively on the surface.

Lieserl felt frustrated. Had they come so far, approached this astonishing mystery, so closely, only for their comms links to fail?

She tapped her helmet. “I feel as if I’ve gone deaf,” she said.

“Me too.” Mark smiled thinly, some of the expression returning to the waxy image of his face. “Well, we’ve certainly lost the voice links from the Northern.” He looked up uneasily. “I wonder what in Lethe is happening up there.”

“Maybe they are trying to recall us.”

Mark shrugged. “Or maybe not.” He looked at her. “Lieserl, do you feel any different? As far as I can tell the links to the central processors back on the Northern are still functioning — although I’m working read-only at the moment.”

She closed her eyes and looked inwards. “Yes. It’s the same for me.” Read-only meant she couldn’t pass her impressions the new memories she was laying down back to the processors on the Northern which were now the core of her awareness. She looked up at the Northern’s steady yellow light. “Do you think we should go back?”

Mark hesitated, looking back at the pod.

Uvarov stirred, like an insect in some glass cocoon, Lieserl thought. “I’m the only one of us who’s in genuine danger here,” he rasped. “The two of you are just projections. Virtual phantasms. You are only wearing those damn suits as crutches for your psyches, in Lethe’s name. Even if this planet exploded now, all you’d lose would be a few hours of data input.” He snarled the last words like an insult.

“What’s your point, Uvarov?” Mark said.

“Get on with your search,” Uvarov snapped. “Stop wasting time. There is nothing you can do about whatever problems are occurring at the Northern. For Life’s sake, look at the bigger picture. The baryonic Universe is coming to an end. What can happen to make things worse than that?”

Mark laughed, a little grimly. “All right, Doctor. Come on, Lieserl.”

They trudged over the surface toward the structure.

The klaxon died. The sudden silence was shocking.

Morrow tapped his ear — he thought self-deprecatingly, as if that would restore the Virtual projection of Louise’s voice.

Milpitas had left his side. With surprising agility the Planner had swum down through the air, away from Morrow and back toward the pond.

There was a grind of metal, high above him. He heard a single scream — an unearthly sound that echoed from the walls, rattling through the silence of the Decks. And now there was another scream — but this time, Morrow realized, it was the product of no human voice; the shriek was of air escaping from a breached hull.

He peered up into the shining air, looking for the breach. There. Against one wall, mist was gathering over a straight-line gash which sliced through a field of dwarf wheat. A literacy-recovery class had been working there; now, people scrambled through the air, away from the billowing fog, screaming.

He heard Milpitas grunt. Morrow looked down.

Milpitas stared down at his midriff and clasped his hands over his belly. His scarred face was creased into an expression of disapproving surprise, and — in that final instant — Morrow was reminded of Planner Milpitas as he had once been: tough minded, controlling, forcing the world to bend to his will.

Then Milpitas folded forward, around a line just below his solar plexus. For the first fraction of a second it looked as if he were doubling over in pain — but, Morrow saw with mounting horror, Milpitas kept on folding, bending until Morrow could hear the crackle of crushed ribs, the deeper snap of vertebrae.

There was nothing visible, nobody near Milpitas; it was as if he were inflicting this unimaginable horror on himself, or as if the Planner’s body had been crumpled in some huge, transparent fist.

Then, it seemed that that same huge fist — powerful, irresistible, invisible grabbed Morrow himself and hurled him down toward the Deck.

He screamed and wrapped his arms around his head.

He smashed into the spherical pond, so lovingly constructed by himself and Milpitas. Reeds and lilies slapped at his face and arms, and brackish water forced itself into his eyes and mouth.

Then he was through the pond, and the Deck surface hurtled up to meet him, unimaginably hard.

The tetrahedron was liberally coated with dust. Mark had the ’bot roll forward and wipe the building’s surface, tentatively. Beneath a half-inch thickness of the dust, the material of the tetrahedron’s construction was milky-white, seamless. The triangular faces gave the structure the look of something flimsy, or temporary, Lieserl thought — like a tent of cloth.

It had been Mark’s suggestion for them to approach this structure in human form. “We want to know — among other things — if people built this thing, and why,” he had argued. “How else are we going to get a genuine feel for the place, unless we look at it through human eyes?” Lieserl hadn’t been sure. To restrict themselves to human form — more than was necessary to interface with Uvarov — had seemed inefficient. But, staring at the structure now, Lieserl realized what a good idea it had been.

“It’s a tetrahedron,” Lieserl observed. “Like an Interface portal.”

“Well, that’s a characteristic signature of human architecture,” Mark murmured. “Doesn’t mean a thing, by itself, though. And from the thickness of that dust, I guess we know this place has been abandoned for a long time.”

“Hmm. The door looks human enough.”

The door was a simple hatchway seven feet tall and three wide, set at the base of one of the tetrahedron’s triangular walls. There was a touchpad control, set at the waist height of an average human.

Mark shrugged. “Let’s try to open it.”

The ’bot rolled forward silently, bouncing a little on the rough surface despite its fat, soft wheels. It extended an arm fitted with a crude mechanical grab, tapped cautiously at the door, and then pushed at the control pad.

The door slid aside, into the fabric of the tetrahedron. A puff of air gushed out at them. A few scraps of dust tumbled out, and, when the air had dispersed, the dust fell in neat parabolae to the surface.

Beyond the door there was a small rectangular chamber, big enough for four or five people. The walls were of the same milky substance as the outer shell, and were unadorned. There was another door, identical to the first, set into the far wall of the chamber.

“At least we know there’s still power,” Mark said.

“This is an airlock,” Lieserl said, looking inside the little chamber. “Plain, functional. Very conventional. Well, what now? Do we go in?”

Mark pointed.

The ’bot was already rolling into the airlock. It bumped over the lip, and came to a halt at the center of the lock.

Lieserl and Mark hesitated for a few seconds; the ’bot waited patiently inside the lock.

Mark grinned. “Evidently, we go in!”

He held out his arm to Lieserl. Arm in arm, they trooped after the robot into the lock.

The lock, containing the ’bot and the two of them, was a little cramped. Lieserl found herself shying away from the ’bot’s huge, dusty wheels, as if she might get her environment suit smeared.

The ’bot reached out and pushed the control to open the next door. There was a hiss of pressure equalization.

The ’bot exposed an array of chemical sensors, and Mark cracked open his faceplate and sniffed elaborately.

“Oh, stop showing off,” Lieserl said.

“Air,” he said. “Earth-normal, more or less. A few strange trace elements. No unusual smells — and quite sterile. We could breathe this stuff if we had to, Lieserl.”

The lock’s inner door swung open, revealing a larger chamber. The ’bot pushed a lamp, magnesium-white, into the chamber, and light flared from the walls. Lieserl caught a glimpse of conventional-looking furniture: beds, chairs, a long desk. The chamber’s walls sloped upwards to a peak; this single room looked large enough to occupy most of the tetrahedral volume of the building.

The ’bot rolled forward. Mark stepped briskly out of the lock and into the chamber; Lieserl followed.

“Mark Wu? Lieserl?” Uvarov’s rasp was loud in her ear.

“Yes, Doctor,” Lieserl replied. “We hear you. You don’t need to shout.”

“Oh, really,” Uvarov said. “Unlike you, I didn’t simply assume that our transmissions would carry through whatever those walls are made of.”

Lieserl smiled at Mark. “Were you worried about us, Uvarov?”

“No. I was worried about the ’bot.”

Lieserl stepped toward the center of the main chamber and looked around.

The walls of the tetrahedral structure sloped up around her, coming to a neat point fifteen feet above her head. She could see partitioned sections in two of the corners. Bedrooms? Bathrooms? A galley, perhaps?

The ’bot scurried around the edge of the room, its multiple arms probing into corners and edges. It left planet-dust tracks behind itself.

The main piece of furniture was a long desk, constructed of what looked — for all the world — like wood. Lieserl could see monitors of some kind inlaid into the desk surface. The monitors were dead, but they looked like reasonably conventional touch-screens. Lieserl reached out a gloved hand, wishing she could feel the wood surface.

There were chairs, in a row, before the desk — four of them, side by side. These were obviously of human construction, with upright backs, padded seats, and two arms studded with controls.

“Mark, look at this,” she said. “These chairs would fit either of us.”

Mark had found something — two objects — at the end of the desk; he had the ’bot roll across and pick the objects up. Mark’s face was lit with wonder; he bent to inspect the first object, held before him in the ’bot’s delicate grab. “This is some kind of stylus,” he said. “Could be something as simple as an ink pen…” The ’bot held up the second object. “But this thing is unmistakable, Lieserl. Look at it. It’s a cup.” His hands on his knees, he looked up at her. “The builders of this place must have been gone a million years. But it’s as if they just stepped outside.”

Uvarov rasped, “Who? I wish you’d speak to me, damn it. What have you found?”

Mark and Lieserl looked at each other.

“People,” Lieserl said. “We’ve found people, Uvarov.”

Mark sat with Louise in her oak-paneled bedroom inside the Great Britain. Mark had called up a Virtual schematic of the Northern’s lifedome; the schematic was a cylinder three feet tall, hovering over her bed. The schematic showed a lifedome which sparkled with glass and light, and the greenery of the forest Deck glowed under the skydome at the crown.

Louise felt something move inside her; the lifedome looked so beautiful — so fragile.

She stared around at the familiar polished walls of her room — it was actually two of the old ship’s state rooms, knocked together and converted. Here was the center of her world, if anywhere was; here were her few pieces of old furniture, her clothes, her first, antique data slate — which still contained the engineering sketches of the Great Britain she’d prepared during her first visit to the old ship as a teenager, five million years and half a Universe away. If only, she thought, if only she could pull this room around her like some huge wooden blanket, never to emerge into the complex horrors of the world…

But here was Mark, politely sitting on the corner of her bed and watching her face. And now he said quietly: “Here it comes, Louise.”

She forced herself to look at the Virtual of the lifedome.

Mark pointed at the mid-section of the lifedome. A horizontal line of blue-white light appeared; it shimmered bale-fully against the clear substance of the lifedome, like a sword blade.

“The string has sliced into us from this side. I guess we can be grateful the relative velocity was actually quite low…”

The string cut easily into the substance of the dome, like a hot wire into butter.

Louise, watching in the silence of her room, felt as if the string were cutting into her own body; she imagined she could hear the shriek of lost air, the screams of her helpless human charges.

Mark looked blank as his processors worked. He said rapidly, “The wake took a slice out of the hull tens of yards thick. Lethe. We’re losing a lot of air, Louise, but the self repair systems are working well… A lot of our infrastructure has gone down quickly — too damn quickly; I think we need to take a look at our redundancies again, if we make it through this…”

“And the Decks? What’s happening in there?”

He hesitated. “I can’t tell, Louise.”

She felt useless; the control panels in the room mocked her with their impotence. She felt the blame for this ghastly accident fall on her shoulders, like a tangible weight. I’m responsible for bollixing up those distance evaluation routines. I’m responsible for insufficient redundancy — and for losing touch with Spinner-of-Rope in the cage, just when we need her most. If only I could talk to Spinner, maybe she could get us out of here. If only —

“The geometry of the string is just as theory predicted,” Mark said. “I’m getting measurements of pi in the regions around the string… 3.1402, compared to the flat-space value of 3.1415926… The conical space has an angle deficit of four minutes of arc.

“At this moment we have a quarter-mile length of string, actually inside the lifedome, Louise. That’s a total mass of four hundred billion billion tons.” Mark looked bemused. “Life, Louise, think about that; that’s the mass of a fair sized moon…”

Her introspection was futile. The destruction of the life dome could be suddenly — mere seconds away. And, in the end, she was helpless. All I could do, in those last, frantic moments, was sound the damn klaxon…

There was a whisper of spider-web light above Spinner. She could see how the string made the stars slide across the sky, just above the lifedome. The encroaching string was like the foregathering of some huge, supernatural storm around the Northern.

Don’t be afraid…

She twisted in her couch and tightened her restraints. “What in Lethe do you expect me to be?” she yelled at Poole. “We’ve been hit by a length of cosmic string, damn it. This could finish us off. I have to get us out of here.” She placed her hands on the waldoes. “But I don’t know what to do. Louise? Louise, can you hear me?”

You know she can’t.

Feverishly, Spinner said, “Maybe we’re already hit; maybe that’s why the connection went down. But what if she managed to program a routine into the waldoes before we lost the connection? Maybe — ”

Come on, Spinner-of-Rope. You know that’s not true.

“But I have to move the ship!” she wailed. The thump of her heartbeat sounded impossibly loud in the confined space of the helmet. “Can’t you see that?”

Yes. Yes, I see that.

“But I don’t know how — or where — without Louise…”

A hand rested over hers. Despite the thickness of her glove fabric, she could feel the warm roughness of Michael Poole’s palm.

I will help you. I’ll show you what you must do.

The invisible fingers tightened, pushing her hands against the waldoes. Behind her, the nightfighter opened its wings.

Morrow, crumpled against the Deck beside the crushed body of Planner Milpitas, stared up into the wake of the cosmic string.

The structure of the middle Decks was fragile; it simply imploded into the string wake. Morrow saw homes which had stood for a thousand years rip loose from the Deck surfaces as if in the grip of some immense tornado; the buildings exploded, and metal sheets spun through the air. The newer structures, spun across the air in zero-gee, crumpled easily as the wake passed. Much of the surface of Deck Two was torn loose and tumbled above him, chunks of metal clattering into each other. Morrow saw patterns of straight lines and arcs on those fragments of Deck: shards of the soulless circular geometry which had dominated the Deck’s layout for centuries.

People, scattered in the air like dolls, clattered against each other in the wake. The string passed through a Temple. The golden tetrahedron — the proudest symbol of human culture — collapsed like a burst balloon around the path of the string, and shards of gold-brown glass, long and lethal, hailed through the air.

And now the string passed through another human body, that of a hapless woman. Morrow heard the banal, mundane sounds of her death: a scream, abruptly cut off, a moist, ripping sound, and the crunch of bone, sounding like a bite into a crisp apple.

The woman’s body, distorted out of recognition, was cast aside; tumbling, it impacted softly with the Deck.

The wake of a cosmic string… The wake was the mechanism that had constructed the large-scale structure of the Universe. It was the seed of galaxies. And we have let it loose inside our ship, Morrow thought.

Once the string passed through the lifedome completely, the Northern would die at last, as surely as a body severed from its head…

Morrow, immersed in his own pain, wanted to close his eyes, succumb to the oblivion of unconsciousness. Was this how it was to end, after a thousand years?

But the quality of the noise above him — the rush of air, the screams — seemed to change.

He stared up.

The string, still cutting easily through the structure, had slowed to a halt.

“Mark,” Louise hissed. “What’s happening?”

The string had cut a full quarter-mile into the lifedome. For a moment the blue glowing string hovered, like a scalpel embedded in flesh.

Then the Virtual display came to life once more. The electric-blue string executed a tight curve and sliced its way back out of the lifedome, exiting perhaps a quarter-mile above its entry point.

Louise wished there was a god, to offer up her thanks.

“It’s done a lot more damage on the way out — but we are left with an intact lifedome,” Mark said. “The ’bots and autonomic systems are sealing up the breaches in the hull.” He looked up at Louise. “I think we’ve made it.”

Louise, floating above her bed, hugged her knees against her chest. “But I don’t understand how, Mark.”

“Spinner-of-Rope saved us,” Mark said simply. “She opened up the discontinuity drive and took us away from there at half lightspeed — and in just the right direction. See?” Mark pointed. “She pulled the ship backwards, and away from the string.”

She looked into his familiar, tired eyes, and wished she could hug him to her. “It was Spinner-of-Rope. You’re right. It must have been. But the voice link to Spinner was one of the first things we lost. And we certainly didn’t have time to work up routines for the waldoes.”

“In fact, we’re still out of touch with Spinner,” Mark said.

“So how did she know?” Louise studied the scarred Virtual lifedome. “The trajectory she chose to get us out of this was almost perfect, Mark. How did she know?”

Spinner-of-Rope buried her faceplate in her gloves; within her environment suit she trembled, uncontrollably.

It’s over, Spinner. You did well. It’s time to look ahead.

“No,” she said. “The string hit the ship. The deaths, the injuries — ”

Don’t dwell on it. You did all you could.

“Really? And did you, Michael Poole?” she spat.

What do you mean?

“Couldn’t you have helped us more? Couldn’t you have warned us that the thing was coming?”

He laughed, softly and sadly. I’m sorry, Spinner. I’m not superhuman. I didn’t have any more warning than your people. I’m pretty much bound by the laws of physics, just as you are…

She dropped her hands and thumped the side of the couch. There was still no link — voice or data — to Louise, and the rest of the crew. She was isolated out here — stuck in the pilot’s cage of an alien ship, with only a five-million year-old ghost for company.

She felt a swelling of laughter, inside her chest; she bit it back.

Spinner-of-Rope?

“I’m scared, Michael Poole. I’m even scared of you.”

I don’t blame you. I’m scared of me.

“I don’t know what to do. What if Louise can’t get back in touch?”

He was silent for a moment. Then: Look, Spinner, your people can’t stay here. In this time frame, I mean.

“Why not?”

Because there’s nothing for you here. The Ring — which you came to find — is ruined. This rubble of string fragments can’t offer you anything.

“Then what?”

You have to move on, Spinner. You have to take your people to where they can find shelter and escape. His hands, warm and firm, closed invisibly over hers once more. I’ll show you. Will you trust me?

“Where are we going?”

In search of the Ring.

“But — but the Ring is here. And it’s destroyed. You said so yourself.”

Yes, he said patiently. But it wasn’t always so…

30

The ’bot rolled fussily across the floor, its fat wheels crunching over the dust it had brought in from the surface of the neutron star planet. It held a bundle of sensors out before it on a flexible arm. Light, brilliant white, glared from the sensor arm. The way the ’bot held out its sensor pack was rather prissy, Lieserl thought, as if the ’bot didn’t quite approve of what it was being forced to inspect in here.

The ’bot rolled up to one of the four chairs and sniffed at it cautiously.

“There’s exotic matter here,” Mark said suddenly.

“What?”

“The ’bot has found exotic matter,” Mark repeated evenly. “Somewhere inside the building.”

Uvarov growled from the pod, “But we’ve seen no evidence of wormhole construction here. And that structure is too small to house a wormhole Interface.”

“I’m just reporting what the ’bot’s telling me,” Mark snapped, letting his irritation show. “Maybe we should gather a few more facts before wasting our time speculating, Uvarov.”

The ’bot was still lingering close to one of the chairs — the second from the left of the row of four, Lieserl noted irrelevantly. As she watched, the ’bot extended more arms, unfolded more packages of sensor equipment; it loomed over the chair menacingly, like some mechanical spider.

Mark walked up to the ’bot, his face expressionless. “It’s somewhere inside the chair. The exoticity…”

“Inside the chair?” Lieserl felt like laughing, almost hysterically. “What happened, did someone drop exotic matter down behind the cushion while watching a Virtual show?”

He glared at her. “Come on, Lieserl. There is a construct of exotic matter embedded in this chair. It’s tiny — only a few fractions of an inch across — but it’s there.” He turned to the ’bot. “Maybe we can cook up some kind of magnified Virtual image…”

Pixels swirled before Lieserl’s face, brushing her cheeks intangibly; she stepped back.

The pixels coalesced into a crude sketch, suspended in the air. It looked like a jewel — clear, complete and seamless hanging before her. There were hints of further structure inside, not yet resolved by the ’bot’s imaging systems.

She recognized the form.

“Lethe. Another tetrahedron,” she said.

“Yes. Another tetrahedron… The form seems to have become a badge of humanity, doesn’t it? But this one is barely a sixteenth of an inch across.”

Pixels of all colors hailed through the interior of the little tetrahedron, as if scrambling for coherence. Lieserl caught elusive, tantalizing hints of structure. At one point it seemed that she could see another, smaller tetrahedron forming, nested inside the first — just as this construct was nested inside the tetrahedral form of the base as a whole. She wondered if the whole of this structure was like a Russian doll, with a series of tetrahedra snuggled neatly inside each other…

The magnified image was rather pleasing, she thought. It reminded her of the toy she’d had during her lightning-brief childhood: a tiny village immersed in a globe of water, with frozen people and plastic snowflakes… Thinking that, she felt a brief, incongruous pang of regret that her childhood, even as unsatisfactory as it had been, was now so remote.

“Well, my exotic matter grain is in there somewhere,” Mark said. “But the ’bot is having trouble getting any further resolution.” He looked confused. “Lieserl, there’s something very strange inside that little tetrahedral box.”

She kept her face expressionless; at times it was quite convenient to be a Virtual — it gave her such control. Strange. Right. But what could be stranger than to be here: on the planet of a neutron star hurtling at lightspeed across the battlefield at the end of time? What can make things stranger than that?

“There’s a droplet of neutron superfluid in there,” Mark said. He peered into the formless interior of the tetrahedron, as if by sheer willpower he might force it to give up its secrets. “Highly dense, at enormous temperatures and pressures… Lieserl, the tetrahedron contains matter at conditions you’d expect to find deep in the interior of a neutron star — in a region beneath the solid crust, called the mantle. That’s what the ’bot is trying to see into.”

Lieserl stared at the swirling mists inside the tetrahedron. She knew that a neutron star had the mass of a normal star, but compressed into a globe only a few miles in diameter. The matter was so dense that electrons and protons were forced together into neutrons; this superfluid of neutrons was a hundred billion billion times as dense as water.

“If that’s so, how are the pressures contained? This construct is like a bomb, waiting to go off.”

He shook his head. “Well, it looks as if the people who built this place found a way. And the construct may have been stable for a long time — millions of years, perhaps. You know, I wish we had more time to spend here. We don’t even know how old this base is — from how many years beyond our time this technology dates.”

“But why construct such a thing?” She stared into the tetrahedron. “Why fill a little box with reconstructed neutron star material? Mark, do you think this was some kind of laboratory, for studying neutron star conditions?”

Uvarov’s ruined voice brayed laughter into her ears. “A laboratory? My dear woman, this is a war zone; I think basic science was unlikely to be on the agenda for the men and women who built this base. Besides, this neutron star is hardly typical. The people who came here placed discontinuity-drive engines at the star’s pole, and drove it across space at close to lightspeed. Now, what research purpose do you think that served?”

Mark ignored him. He squatted down on his haunches before the image and peered up at it; the glow of the shifting pixels inside the tetrahedron cast highlights from his face and environment suit. “I don’t think the stuff in there was reconstructed, Lieserl.”

“What do you mean?”

“Think about it.” He pointed at the image. “We know there is exotic matter in there… and as far as we know the primary purpose of exotic matter is the construction of spacetime wormholes. I think there’s a wormhole Interface in there, Lieserl.”

She frowned. “Wormhole mouths are hundreds of yards — or miles — across.”

He straightened up. “That’s true of the Interfaces we can construct. Who knows what will be possible in the future? Or rather — ”

“We know what you mean,” Uvarov snapped from the pod.

“Let’s suppose there is a wormhole mouth inside this tiny construct,” Mark said. “A wormhole so fine it’s just a thread… but it leads across space, to the interior of the neutron star. Lieserl, I think the neutron superfluid in here isn’t some human reconstruction — I think it’s a sample of material taken from the neutron star itself.”

Lieserl, involuntarily, glanced around the chamber, as if she might see the miniature wormhole threading across space, a shining trail connecting this bland, human environment with the impossibly hostile heart of a neutron star.

“But why?”

“Isn’t it obvious?” Uvarov snapped.

Mark was smiling at her; evidently he had worked it out too.

She felt slow, stupid, unimaginative. “Just tell me,” she said dully.

Mark said, “Lieserl, the link is there so the humans who built this base could reach the interior of the neutron star. I think they downloaded equipment into there: nanomachines, ’bots of some kind — maybe even some analogue of humans.

“They populated the neutron star, Lieserl.”

Uvarov rumbled assent. “More than that,” he rasped. “They engineered the damn thing.”

Closed timelike curves, Spinner-of-Rope.

The nightfighter arced through the muddled, relativity distorted sky; the neutron star system wheeled around Spinner like some gaudy light display. Behind her, the huge wings of the Xeelee nightfighter beat at space, so vigorously Spinner almost imagined she could hear the rustle of immense, impossible feathers.

She felt her small fingers tremble inside gloves that suddenly seemed much too big for her. But Michael Poole’s hands rested over hers, large, warm.

The ship surged forward.

We are going to build closed timelike curves…

Ignoring the protests of her tired back, Louise straightened up and pushed herself away from the Deck surface. She launched into the air, the muscles of her legs aching, and she let air resistance slow her to a halt a few feet above the Deck.

Once this had been a park, near the heart of Deck Two. Now, the park had become the bottom layer of an improvised, three-dimensional hospital, and the long grass was invisible beneath a layer of bodies, bandaging, medical supplies. A rough rectangular array of ropes had been set up, stretching upwards from the Deck surface through thirty feet. Patients were being lodged loosely inside the array; they looked like specks of blood and dirt inside some huge honeycomb of air, Louise thought.

A short distance away a group of bodies — unmoving, wrapped in sheets — had been gathered together in the air and tethered roughly to the frame of what had once been a greenhouse.

Lieserl approached Louise tentatively. She reached out, as if she wanted to hold Louise’s hand. “You should rest,” she said.

Louise shook her head angrily. “No time for that.” She took a deep breath, but her lungs quickly filled up with the hospital’s stench of blood and urine. She coughed, and ran an arm across her forehead, aware that it must be leaving a trail there of blood and sweat. “Damn it. Damn all of this.”

“Come on, Louise. You’re doing your best.”

“No. That isn’t good enough. Not any more. I should have designed for this scenario, for a catastrophic failure of the lifedome. Lieserl, we’re overwhelmed. We’ve converted all the AS treatment bays into casualty treatment centers, and we’re still overrun. Look at this so-called hospital we’ve had to improvise. It’s like something out of the Dark Ages.”

“Louise, there’s nothing you could have done. We just didn’t have the resources to cope with this.”

“But we should have. Lieserl, the doctors and ’bots are operating triage here. Triage, on my starship.”

…And it didn’t help that I diverted most of our supply of medical nanobots to the hull… Instead of working here with the people — crawling through shattered bodies, repairing broken blood vessels, fighting to keep bacterial infection contained within torn abdominal cavities — the nanobots had been press-ganged, roughly — and on her decision — into crawling over the crude patches applied hurriedly to the breached hull, trying inexpertly to knit the torn metal into a seamless whole once more.

She clenched her hands into fists, digging her nails into her palms. “What if the Xeelee are studying us now? What will they think of us? I’ve brought these people across a hundred and fifty million light years — and five million years only to let them die like animals…”

Lieserl faced her squarely, her small, solid fists on her hips; lines clustered around her wide mouth as she glared at Louise. “That’s sentimental garbage,” she snapped. “I’m surprised at you, Louise Ye Armonk. Listen to me: what is at issue here is not how you feel. You are trying to survive — to find a way to permit the race to survive.”

Lieserl’s stern, lined face, with the strong nose and deep eyes, reminded Louise suddenly of an overbearing mother. She snapped back, “What do you know of how I feel? I’m a human, damn it. Not a — a — ”

“An AI?” Lieserl met her gaze evenly.

“Oh, Lethe, Lieserl. I’m sorry.”

“It’s all right, Louise. You’re quite right. I am an artifact. I have many inhuman attributes.” She smiled. “For instance, at this moment I have two foci of consciousness, functioning independently: one here, and one down on the planet. But…” She sighed. “I was once human, Louise. If briefly. So I do understand.”

“I know, Lieserl. I’m sorry.” Louise had never found it easy to express affection. With a struggle, she said: “In fact, you’re one of the most human people I’ve ever met.”

Lieserl looked around at the makeshift hospital, following the soft cries of the wounded. “Louise,” she said slowly, “I have a long perspective. Think of the story of the race. Our timelines emerged from the oceans, and for millions of years circled the Sun with Earth. Then, in a brief, spectacular explosion of causality, the timelines erupted in wild scribbles, across the Universe. Humanity was everywhere.

“But now, our possibilities have reduced.

“Louise, all the potential paths of the race — all the time lines, running from those ancient oceans of the past, through millions of years to an unknown future — all of them have narrowed to a single event in spacetime: here, on this ship, now. And that event is under your control.”

Lieserl’s face loomed before Louise now, filling her vision; Louise looked into her soft, vulnerable eyes, and — for the first time, really she had a sudden, deep insight into Lieserl’s personality. This woman really is ancient — ancient, and wise.

“Louise, you are not a woman — or rather, you are more than a woman. You are a survival mechanism: the best to be found, for this crucial instant, by our genes, and our culture, and our minds. If you didn’t have the strength within you now, to deliver us through this causal gateway to the future, you would not have been chosen. But you do have the strength to continue,” Lieserl said. “To find a way through. Look within yourself, Louise. Tap into that strength…”

There was a deep, almost subsonic groan, all around Louise. It sounded like thunder, she thought.

It was the sound of metal, under immense stress.

She pulled away from Lieserl and twisted in the air. She looked across at the section of hull breached by the arc of string. The patch that had been applied across the string damage gleamed brightly, fresh and polished, at the center of the grass-coated hull surface. A stress failure — another breach of the lifedome — would kill them all. But the patch looked as if it was holding up okay… not that a visual inspection from this distance meant anything.

As if on cue, a projection of Mark’s head materialized before her. “Louise, I’m sorry.”

“What is it?”

“Come with me. We need to talk.”

“No,” she said. Suddenly, she felt enormously weary. “No more talk, Mark. I’ve done enough damage already.”

Behind her, Lieserl said warningly: “Louise…”

“I heard what you said, Lieserl.” Louise smiled. “But it’s all a little too mystical for a tired old engineer like me. I’m going to stay here. Help out in the hospital.”

Lieserl frowned at her. “Louise, you’re an engineer, not a doctor. Frankly, I wouldn’t want you treating me.”

Mark smiled. “Besides, we don’t have time for all this self pity, Louise. This is important.”

She sighed. “What is?”

He whispered, in a surprisingly unrealistic hiss, “Didn’t you hear the hull stress noise? Spinner is moving the ship again.”

Think of spacetime as a matrix, Michael Poole whispered. A four-dimensional grid, labeled by distance and duration. There are events: points in time and space, at nodes of the grid. These are the incidents that mark out our lives. And, connecting the events, there are trajectories.

The starbow across the sky broadened, now. That meant her speed had reduced, since the relativistic distortion was lessened. Spinner called up a faceplate display subvocally. Yes: the ship’s velocity had fallen to a fraction over half lightspeed.

Trajectories are paths through spacetime, Poole said. There are timelike trajectories, and there are spacelike trajectories. A ship going slower than light follows a timelike path. And, Spinner, we — all humans, since the beginning of history — work our snail-like way along timelike trajectories into the future. At last, our world lines will terminate at a place called timelike infinity at the infinitely remote, true end of time.

But “spacelike” means moving faster than light. A tachyon — a faster-than-light particle — follows a spacelike path, as does this nightfighter under hyperdrive.

She twisted in her seat. Already the neutron star system had vanished, into the red-shift distance. And directly ahead of her there was a cloud of cosmic string; space looked as if it were criss-crossed by fractures, around which blue shifted star images slid like oil drops.

Poole’s hands, invisible, tightened around hers as the ship threw itself into the cloud of string.

We know at least three ways to follow spacelike paths, Spinner-of-Rope: three ways to travel faster than light. We can use the Xeelee hyperdrive, of course. Or we can use spacetime wormholes. Or, Poole said slowly, we can use the conical spacetime around a length of cosmic string…

Think of the gravitational tensing effect that produces double images of stars around strings. A photon coming around one side of the string can take tens of thousands of years longer to reach our telescopes than a photon following a path on the other side of the string.

So, by passing through the string’s conical deficit, we could actually outrun a beam of light… There was string all around the ship, now, tangled, complex, an array of it receding to infinity. A pair of string lengths, so twisted around each other they were almost braided, swept over her head. She looked up. The strings trailed dazzling highways of refracting star images.

Behind her the huge wings spread wide, exultant.

This damn nightfighter was made for this, she thought.

Under Poole’s guidance, Spinner brought the craft to a dead halt; the discontinuity wings cupped as they tore at space. Then Spinner turned the craft around rapidly — impossibly rapidly — and sent it hurtling at the string pair once more. The nightfighter soared upwards, and this time the two strings passed underneath the ship’s bow.

…And if you can move along spacelike paths, Spinner-of Rope, you can construct closed timelike curves.

The neutron star system was old.

Once the system had been a spectacular binary pair, adorning some galaxy lost in the sky. Then one of the stars had suffered a supernova explosion, briefly and gloriously outshining its parent galaxy. The explosion had destroyed any planets, and damaged the companion star. After that, the remnant neutron star slowly cooled, glitching as it spun like some giant stirring in its sleep, while its companion star shed its life-blood hydrogen fuel over the neutron star’s wizened flesh. Slowly, too, the ring of lost gas formed, and the system’s strange, spectral second system of planets coalesced.

Then human beings had come here.

The humans soared about the system, surveying. They settled on the largest planet in the smoke ring. They threw microscopic wormhole mouths into the cooling corpse of the neutron star, and down through the wormholes they poured devices and — perhaps — human-analogues, made robust enough to survive in the neutron star’s impossibly rigorous environment.

The devices and human-analogues had been tiny, like finely jewelled toys.

The human-analogues and their devices swarmed to a magnetic pole of the neutron star, and great machines were erected there: discontinuity-drives, perhaps powered by the immense energy reserves of the neutron star itself.

Slowly at first, then with increasing acceleration, the neutron star — dragging its attendant companion, ring and planets with it — was forced out of its parent galaxy and thrown across space, a bullet of stellar mass fired at almost light speed.

“A bullet. Yes.” In the pod, Uvarov mused. “An apt term.”

Lieserl stared at the swirling, unresolved pixels inside the Virtual image’s clear tetrahedral frame. “I wonder if there are still people in there,” she said.

Mark frowned. “Where?”

“People-analogues. Inside the neutron star. I wonder if they’ve survived.”

He shrugged, evidently indifferent. “I doubt it. Unless they were needed for maintenance, they would surely have been shut down after their function was concluded.”

Shut down… But these were people. What if they hadn’t been “shut down”? Lieserl closed her eyes and tried to imagine. How would it be, to live her life as a tiny, fish-like creature less than a hair’s-breadth tall, living inside the flux-ridden mantle of a neutron star? What would her world be like?

“A bullet,” Uvarov said again. “And a bullet, fired by our forebears — directly at the heart of this Xeelee construct.”

She opened her eyes.

Mark was frowning. “What are you talking about, Uvarov?”

“Can’t you see it yet? Mark, what do you imagine the purpose of this great engineering spectacle was? We already know from the Superet data, and the fragments provided to us by Lieserl — that the rivalry between humanity and Xeelee persisted for millions of years. More than persisted — it grew in that time, becoming an obsession which — in the end — consumed mankind.”

Lieserl said, “Are you saying that all of this — the discontinuity engines, the hurling of the neutron star across space — all of this was intended as an assault on the Xeelee?”

“But that’s insane,” Mark said.

“Of course it is,” Uvarov said lightly. “My dear friends, we’ve plenty of evidence that humanity isn’t a particularly intelligent species — not compared to its great rivals the Xeelee, at any rate. And I have never believed that humanity, collectively, is entirely sane either.”

“You should know, Doctor,” Mark growled.

“I don’t understand,” Lieserl said. “Humans must have known about the photino birds — damn it, I told them! They must have seen what danger the birds represented to the future of all baryonic species. And they must have seen that the Xeelee — if remote and incomprehensible — were at least baryonic too. So the goals of the Xeelee, if directed against the birds, had to be in the long-term interests of mankind.”

Uvarov laughed at her. “I’m afraid you’re still looking for rational explanations for irrational behavior, my dear. Lieserl, I believe that the Xeelee grew into the position in human souls once occupied by images of gods and demons. But here, at last, was a god who was finite — who occupied the same mortal realm as humans. A god who could be attacked. And attack we did: down through the long ages, while the stars went out around us, all but ignored.”

“And so,” Mark said grimly, “we fired off a neutron star at the Ring.”

“A spectacular gesture,” Uvarov said. “Perhaps humanity’s greatest engineering feat… But, ultimately, futile. For how could a mere neutron star disrupt a loop of cosmic string? And besides, the Xeelee starbreaker technology was surely sufficient to destroy the star before — ”

“But it didn’t work,” Lieserl said slowly.

Mark had been staring at the sensor ’bot; the squat machine had come to a halt before the chair, its sensor arms suspended in the air. “What do you mean?”

“Think about it,” she said. “The neutron star is heading away from the site of the Ring. And it’s clearly not been disrupted by starbreakers.”

“Yes. So something went wrong,” Uvarov said. “Well, the precise sequence hardly matters, Lieserl. And — ”

It happened in a heartbeat.

The light died. The ancient structure was flooded with darkness.

Louise and Mark left the improvised hospital and found an abandoned house. The house was bereft of furniture, its owners gone to live in the zero-gee sky (but, of course, the zero-gee dwellings were gone now, Louise noted morosely, swept out of the sky by the cosmic string incursion).

Mark quickly created a Virtual diagram in the air: a geometrical sketch of lines and angles, lettered and arrowed.

Louise couldn’t help but smile. “Lethe, Mark. At a time like this, you give me a diagram Euclid would have recognized.”

He looked at her seriously. “Louise, working out the spacetime geometry of a cosmic string is a hard problem in general relativity. But, given that geometry, all the rest of it is no more than Pythagoras’ theorem…

“As near as I can figure out, this is what Spinner is up to.” There was a pair of tubes in the air, glowing electric blue, like neon. “We are flying around a pair of cosmic strings. Now, here are the angle deficits of the strings’ conical spacetimes.” Wedges of air, like long cheese slices, were illuminated pale blue; one wedge trailed each string length.

“Okay. Here comes the Northern.” The ship was represented by a cartoon sketch of a sycamore seed in black. “You can see we’re traveling on a curving path around the string pair, going against the strings’ own rotation.”

Now the seed arced into the wedge-shaped angle deficit glow of one of the strings. As soon as it had entered the boundary it vanished, to reappear instantly at the far side of the deficit.

Mark snapped his fingers. “See that? Faster-than-light travel: a spacelike trajectory right across the deficit.”

Now the little ship-model came arcing back and flickered through the second string’s angle deficit. “Louise, the strings are traveling just under the speed of light — within three decimal places of it, actually. Spinner has the Northern traveling at a little over half lightspeed. The turning curves, and the accelerations, are incredible… The domain wall inertial shielding seems to be working pretty well, although there’s a little leakage.”

Louise nodded. “Right. Which is why the Northern is complaining.”

“Yeah. Louise, the Northern wasn’t designed for this — and neither was our bastardized lash-up of Northern and nightfighter. But there’s nothing we can do. We’ll just have to pray the whole mess holds together until Spinner-of-Rope finishes her joy-riding…

“Anyway, the trajectory she’s following is quite precisely machined… We’re passing from side to side of the string pair in light-minutes, but we’re crossing light-years thanks to the spacelike savings. Louise, I think Spinner-of-Rope is assembling closed timelike curves, from these spacelike trajectories.”

Louise stared at the seed-craft; she felt an impulse to reach out and pluck it from the air. “But why, Mark? And how?”

“I know what a closed timelike curve is,” Spinner said. Again she dragged the ship to a halt and whirled its nose around toward the string; although she was still shielded from the impossible accelerations she felt herself gasp as the Universe lurched around her. “The original mission of the Great Northern, with its wormhole, was to follow a segment of a closed timelike curve…”

Yes. A closed timelike curve is a circle in time. By following a closed timelike curve all the way to its starting point, you would at last meet yourself, Spinner-of Rope… Closed timelike curves allow you to travel through time, and into the past.

Again the nightfighter hurled itself at the cosmic string pair; again Spinner hauled at the waldoes, dragging the ship around. The huge wings beat at spacetime.

She screamed, “How much longer, damn it?”

Spinner, each traverse around the string pair is taking us a thousand years into the past. But we need to travel back through a hundred millennia, or more…

“A hundred traverses,” she whispered.

Can you do it, Spinner? Do you have the strength?

“No,” she said. “But I don’t think I have much choice, do I?”

Lieserl looked around the darkened chamber, confused. The ’bot’s brilliant lantern had been extinguished. Suddenly the walls were dim gray sheets, closing over her head, claustrophobic.

“Lieserl.” Mark’s face loomed before her, erupting out of the darkness; his blue eyes, white teeth were vivid. He moved with nanosecond speed, the slowness of humanity finally abandoned.

Dimly, she was aware of poor Uvarov sitting in the pod. He was frozen in human time, and unable to follow their high speed insect-buzz. “What is it? What’s happened?”

“The ’bot has failed. Lieserl, it was controlled by the ship’s processors. The download link from the ship must have gone down…”

Immediately, she felt that loss of processor support. She felt as if her mind had been plunged into a twilight cavern, echoing; she felt herself drift away.

“They’ve abandoned us.”

“Probably they had no choice, Lieserl.”

I am to experience death, then. But — so suddenly?

Lieserl would survive, of course — as would Mark, as projections on board the Northern. But this projection — she, this unique branch of her ancient consciousness — couldn’t be sustained solely by the limited processors on the pod.

She felt a spasm of regret that she would never be able to tell Louise and Spinner-of-Rope about the wonderful little people embedded inside the neutron star flux.

She reached for Mark. Their environment suits melted away; desperately they pressed their bodies against each other. With deep, savage longing, she sought Mark’s warm mouth with her lips, and -

“Lethe. And we can’t even talk to her.” Louise looked out of the house and across the lifedome, in the vague direction of the nightfighter cage. “Mark, Spinner is a smart woman, but she’s no expert on string dynamics. And she’s out there without significant processor support. I don’t see how she’s even calculating the trajectories we’re following.”

Mark frowned. “I — wait.” He held up a hand, and his expression turned inward, becoming blank.

“What is it?”

“We’ve stopped. I mean, the traverses around the string pair have been halted.” He thought for a moment. “Louise, I counted a hundred and seven complete circuits…”

“Louise? Mark?”

The voice sounded out of the air close to Louise’s ear. “Yes, Trapper-of-Frogs. I hear you. Where are you?”

“I’m in the forest. I — ”

“Yes?”

“I think you’d better get up here.”

Louise looked at Mark; he was frowning, and no doubt some sub-projection of him was already with Trapper.

“Why?” Louise asked. “What’s wrong. Trapper?”

“Nothing’s wrong. Not exactly. It’s just — different…”

Michael Poole’s invisible ghost-touch evaporated. Spinner-of-Rope lifted her hands from the waldoes.

Her job was done, then. She pulled her fingers inside the body of her gloves and balled her stiff hands into fists, digging her nails into the palms of her hands. She felt herself shudder, from fear and exhaustion. There was a stabbing in the small of her back, and across her shoulder blades, just below her neck; she twisted in her couch and flexed her spine, trying to work out the stiffness.

Then she looked out, beyond the construction-material cage, for the first time.

31

“Dr. Uvarov. Dr. Garry Uvarov.”

The voice, flat and mechanical, roused him from a broken sleep.

He opened his mouth to reply, and ropy saliva looped across his lips. “What is it now?”

“Is there anything you require?” The voice, generated by the pod’s limited processors, didn’t even bear a semblance of humanity, and it came — maddeningly! — from all around him.

“Yes,” he said. He felt himself shivering, distantly; he felt cold. Was the power in here failing already?

How long had it been, since his abrupt abandonment by Lieserl and Mark Wu?

“Yes,” he told the pod again. “Yes, there is something I require. Take me back to the Northern.”

The pod paused, for long seconds.

Uvarov felt the cold settle over his bones. Was this how he was to die, suspended in the thoughts of an idiot mechanical? Was he to suffer a final betrayal at the hands of technology, just as the AS nanobots had been slowly killing him for years?

Well, if he was to die, he would take with him one deep and intense regret: that he had not lived to see the conclusion of his grand design, his experiment at extending the natural longevity of his race. He knew how others had seen him: as obsessed with his eugenics objectives, as a monomaniac perhaps. But — ah! What an achievement it would have been! What a monument…

Ambition burned within him still, intense, almost all consuming, betrayed by the failure of his body.

His thoughts softened, and he felt himself grow more diffuse, his awareness drifting off into the warm, comfortable caverns of his memory.

The pod spoke again. “I’m unable to comply with your request, Doctor. I can’t obtain a fix on the Northern. I’m sorry. Would you like me to — ”

“Then kill me.” He twisted his head from side to side, relishing the stabs of pain in his neck. “I’m stranded here. I’m going to die, as soon as my supplies run out. Kill me now. Turn off the damn power.”

“I can’t comply with that, either, Dr. Uvarov.”

But Uvarov was no longer listening. Once more he felt himself falling into a troubled — perhaps final — sleep, and his ruined lips moved slowly.

“Kill me, you damn mechanical…”

32

The torus of ragged, fragmented string loops was gone. Now, cosmic string crossed the cavity: great, wild, triumphant whorls of it, shining a false electric blue in the sky dome’s imager.

This one, tremendous, complex, multiple loop of string filled the cavity at the bottom of the gravity well. This was — astonishingly, unbearably — a single object, an artifact, at least ten million light-years across.

Louise Ye Armonk — with Mark, Lieserl and Morrow — hovered on zero-gee scooters, suspended beneath the crown of the skydome. Beneath Louise — she was distantly aware — the layers of forest were filled with the rich, comforting noises: the calls of birds and monkeys and the soft burps of frogs, sounds of busy life which persisted even here at the end of time…

Beyond the clear dome, string filled the Universe.

Here, a hundred thousand years into the past, the galaxies still fell, fragmenting and blue-shifted, into the deepest gravity well in the Universe. And the Northern had emerged from its jaunts through the string loop’s spacetime defects to find itself once more inside a star-walled cavity, at the bottom of this Universal well.

There the similarity ended, though, Louise thought. The cavity walls were much smoother than in the future, containing rather fewer of the ragged holes she’d noted… The walls looked almost artificially smooth here, she thought uneasily.

And, of course, there was the Ring, whole and magnificent.

The Ring was a hoop woven from a billion-light-year length of cosmic string. The Northern was positioned somewhere above the plane of the Ring. The near side of the artifact formed a tangled, impenetrable fence over the lifedome, twisted exuberantly into arcs and cusps, with shards of galaxy images glittering through the morass of spacetime defects. And the far side of the object was visible as a pale, hard band, remote across the blue-shifted sky.

The rough disc of space enclosed by the Ring — a disc no less than ten million light-years across, Louise reminded herself — seemed virtually empty. Perhaps, she mused, in this era the Xeelee were actively working to keep that central region clear.

…Clear, Louise saw as she looked more carefully, save for a single, glowing point of light, right at the geometric center of the Ring. She saw how Lieserl was staring into that point of light, her mouth half-open.

Spinner-of-Rope’s precipitate action had delivered them, back through time, to another snapshot-timeslice of this war in Heaven… and this was, it seemed, an era not far removed from the Ring’s final fall.

She was aware of their eyes — Mark’s, Lieserl’s, Morrow’s resting on her, expectantly. On her.

Remember what Lieserl said, she told herself. I’m a survival mechanism. That’s all. I have to keep functioning, for just a little while longer… She reached deep inside her.

She clapped her hands. “All right, people — Mark, Lieserl. Let’s do some work. I think it’s obvious we’ve delivered ourselves right into the middle of a war zone. We know that, at this moment, the photino birds must be hitting this Ring from all sides — because, within a hundred thousand years, we know that the Ring is going to be destroyed. That gives me the feeling that we don’t have much time, before one side or other notices we’re here…”

“I think you’re right, Louise,” Mark said. Both the Virtuals, on high-capacity data links to the central processors, were working on different aspects of the situation. “I don’t think we should be fooled by the fact that most of the action in this incredible war seems to be occurring at sublight velocities, so that — on this scale it has all the pace of an ant column crossing the Sahara. Let’s not forget the Xeelee have a hyperdrive — which we’ve stolen — and, for all we know, so do the photino birds. We could be discovered at any time.”

“So give me a summary of the environment.”

Mark nodded. “First of all, our position in time: Spinner-of-Rope constructed enough closed timelike paths for us to have traveled a hundred thousand years into the past, back from the era to which our first journey brought us.” He raised his face to the skydome and rose into the air by a few feet, absently forgetting to take his Virtual-scooter with him. “The Ring is complete in this era, as far as we can tell. Its mass is immense — in fact we’re suffering inertial drag from it. Kind of a lot of drag, in fact… We’re being hauled around, through space, by the Ring. Spinner-of-Rope seems to be compensating…”

“Lieserl. Tell me what you have.”

Lieserl seemed to have to tear her eyes away from that tantalizing point of light at the heart of the Ring. She looked down at Louise.

“I have the Ring, Louise. We have been restored to an era before its destruction. Bolder’s Ring is a single loop of cosmic string… but an immense one, no less than ten million light-years across and with the mass of tens of thousands of galaxies, united into one seamless whole. The string is twisted over on itself like wool wrapped around a skein; the Ring’s topography is made up of string arcs moving at close to lightspeed, and cusps which actually reach light speed. The motion is complex, but — as far as I can tell it’s non-intersecting. The Ring could persist forever.

“Louise, there is no way this monster could have formed naturally. Our best theories say that any natural string loops should be a mere thousand light-years across.” She looked up, and the blue false color of the string images caught her profile, picking out the lines around her eyes. “Somehow — ” she laughed briefly ” — somehow the Xeelee found a way to drag cosmic string across space — or else to manufacture it on a truly heroic scale — and then to knit it up into this immense artifact.”

Louise stared up at the Ring, tracing the tangle of string around the sky, letting Lieserl’s statistics pour through her head. And I might have died without seeing this. Thank you. Oh, thank you…

“The cosmology here is… spectacular,” Lieserl said, smiling. “We have, essentially, an extremely massive torus, rotating very rapidly. And it’s devastating the structure of spacetime. The sheer mass of the Ring has generated a gravity well so deep that matter — galaxies — is being drawn in, toward this point, across hundreds of millions of light years. Even our original Galaxy, the Galaxy of mankind, was drawn by the Ring’s mass. So we know that the Ring was indeed the ‘Great Attractor’ identified by human astronomers.

“And the rotation has significant effects. Louise, we’re on the fringe of a Kerr metric — the classic relativistic solution to the gravitational field of a rotating mass. In fact, this is what’s called a maximal Kerr metric: because the torus is spinning so fast the angular momentum far exceeds the mass, in gravitational units…

“As Mark said, the Ring’s rotation is exerting a large torque on the ship. This is inertial drag: the twisting of spacetime around the rotating Ring.”

Morrow frowned. “Inertial drag?”

Lieserl said, “Morrow, naive ideas of gravity predicted that the spin of an object wouldn’t affect its gravitational field. No matter how fast a star rotated, you’d be attracted simply toward its center, just as if it wasn’t rotating at all.

“But relativity tells us that isn’t true. There are nonlinear terms in the equations which couple the rotating mass to the external field. In other words, a spinning object drags space around with it,” she said. “Inertial drag. And that’s the torque the Northern is experiencing now.”

“What else?” Louise asked. “Mark?”

He nodded. “The first point is, we’re drowning in radio wavelength photons — ”

That was unexpected. “What are you talking about?”

“I mean it,” he said seriously, turning to face her. “That’s the single most significant difference in our gross physical environment, compared to the era we came from: we’re now immersed in a dense mush of radio waves.” He looked absent for a moment. “And the intensity of it is increasing. There’s an amplification going on, slow, but significant on the timescales of this war; the doubling time is around a thousand years. Louise, none of this shows up in the future era. By then, the radio photons will be gone.”

Louise shook her head. “I can’t make sense of this. What’s causing the amplification?”

He shrugged, theatrically. “Beats me.” He glanced around the sky. “But look around. The Ring is contained in a shell of galactic material, Louise. The frequencies of the radio waves are below the plasma frequency of the interstellar medium. So the waves are trapped in this galaxy-walled box. We’re inside an immense resonant cavity, ten million light years across, with reflecting walls.”

Morrow looked beyond the skydome uncertainly. “Trapped? But what happens when — ”

Lieserl cut in, “Mark, I think I’ve figured it out. The cause of the radio-wave amplification.”

He glanced at her. “What?”

“It’s the inertial drag. We’re seeing super-radiant scattering from the gravitational field. A photon, falling into the Ring’s gravity well, is coupled to the Ring by the inertial drag, and is then thrown out with additional energy — ”

“Ah. Right.” Mark nodded, looking distant. “That would give an amplification of a few tenths of one percent each traverse… just about fitting my observations.”

Morrow frowned. “Did I understand that? It sounds as if the photons are doing gravitational slingshots around this Ring.”

Louise smiled at him, sensing his fear. “That’s right. The inertial drag is letting each photon extract a little energy from the Ring; the radiation is amplified, and the Ring is left spinning just a fraction slower…

“Lieserl. Tell us more about the spacetime metric.” She looked up, at the point of light at the heart of the Ring. “What do we see, there, at the center?”

Lieserl looked up, her face composed. “I think you know, Louise. It is a singularity, at the center of the Ring itself. The singularity is hoop-shaped, a circular flaw in space: a rip, caused by the rotation of the immense mass of the Ring. The singularity is about three hundred light-years across — obviously a lot smaller than the diameter of the material Ring…

“If the Ring were spinning more slowly, the Kerr metric would be quite well behaved. The singularity would be cloaked in two event horizons — one-way membranes into the center — and, beyond them, by an ergosphere: a region in which the inertial drag is so strong that nothing sublight can resist it. If we were in an ergosphere, we’d have no choice but to rotate with the Ring. In fact, if it weren’t rotating at all, the Kerr field would collapse into a simple, stationary black hole, with a point singularity, a single event horizon and no ergosphere.

“But the Ring is spinning… and too rapidly to permit the formation of an event horizon, or an ergosphere. And so…”

Louise prompted, “Yes, Lieserl?”

“And so, the singularity is naked.”

Michael Poole sat with his legs crossed comfortably on the shoulder of the nightfighter. His gaze was on Spinner’s face, steady, direct.

The Ring is a machine, whose sole purpose is to manufacture that naked singularity. Don’t you see? The Xeelee constructed this huge Ring and set it spinning — in order to tear a hole in the Universe.

Spinner-of-Rope enhanced the false-color of the central singularity in her faceplate imager. The flaw looked like a solid disc — a coin, perhaps — almost on edge toward her, but tipped slightly so that she could see its upper surface.

In that surface, white starlight swam. (White?)

She said to Poole, “The Xeelee built all of this — they modified history, disrupted spacetime, drew in galaxies to their destruction across hundreds of millions of light-years — just for this?”

Poole lifted his eyebrows. It is the greatest baryonic artifact, Spinner-of Rope. The greatest achievement of the Xeelee…

The singularity was like a jewel, surrounded by the undisciplined string scribble of the Ring itself.

“It’s very beautiful,” she conceded.

Poole smiled. Ah, but its beauty lies in what it does…

He turned his gaunt, tired face up to the singularity. Spinner-of-Rope, humans have imputed many purposes to this artifact. But the Ring is not a fortress, or a last redoubt, or a battleship, or a base from which the Xeelee can reclaim their baryonic Universe, he said sadly. Spinner, the Xeelee know they have lost this war in Heaven. Perhaps they have always known that, even from the dawn of their history.

“I don’t understand.”

Spinner, the singularity is an escape hatch.

Lieserl and Mark turned to each other, inhumanly quickly. They stared into each other’s eyes, as if exchanging data by some means invisible to humans, their blank expressions tike mirror images.

“What is it?” Louise asked. “What’s happened?”

Pixels, defects in the Virtual projection, crawled across Mark’s cheek. “We need Spinner-of-Rope,” he snapped. “We can’t wait for the repairs to the data links. We’re trying to find bypasses — working quickly — ”

Louise frowned. “Why?”

Mark turned to her, his face expressionless. “We’re in trouble, Louise. The cops are here.”

Spinner-of-Rope asked, “How do you destroy a loop of cosmic string ten million light-years across?”

It isn’t so difficult… if you have the resources of a universe, and a billion years, to play with, Spinner-of Rope. Poole, perched on the shoulder of the nightfighter, pointed at a hail of infalling galaxies swamping a nearby section of the Ring. If the Ring tangles — if cosmic string self-intersects — it cuts itself, he said. It intercommutes. And a new subloop is formed, budding off the old. And perhaps that subloop, too, will self-intersect, and split into still smaller loops… and so on.

Spinner nodded. “I think I understand. It would be an exponential process, once started. Pretty soon, the Ring would decay into the torus of debris we found will find a hundred thousand years from now…”

Yes. No doubt the motion of the Ring has been designed by the Xeelee so that it does not cut itself. But all one need do is start the process, by disrupting the Ring’s periodic behavior. And that is evidently what the photino birds are endeavoring to do, by hurling galaxies — like thrown rocks at the Ring.

Spinner sniffed. “Seems kind of a crude technique.”

Poole laughed. Baryonic chauvinism, Spinner-of-Rope? Besides, the birds have other mechanisms. I —

“…Spinner. Spinner-of-Rope. Can you hear me?”

Spinner sat bolt upright in her couch and clutched at her helmet. “Lieserl? Is that you?”

“Listen to me. We don’t have much time.”

“Oh, Lieserl, I was beginning to think I’d never — ”

“Spinner! Shut up, damn you, and listen.”

Spinner subsided. She’d never heard Lieserl use a tone like that before.

“Use the waldoes, Spinner. You have to get us out of here. Take us straight up, with the hyperdrive, over the plane of the Ring. Have you got that? Use the longest jump distance you can find. We’ll try to patch subroutines into the waldoes, but — ”

“Lieserl, you’re scaring the pants off me. Can’t you tell me what’s wrong?”

“No time, Spinner. Please. Just do it…”

The Universe darkened.

For a bleak, heart-stopping instant Spinner thought she was going blind. But the telltales on the waldoes still gleamed at her, as brightly as ever.

She looked up. There was something before the ship, occluding the blue-shifted galaxy fragments, hiding the Ring.

She saw night-dark wings, spread to their fullest extent, looming over the Northern.

Nightfighters.

She twisted in her seat. There were hundreds of them — impossibly many, dark lanterns hanging in the sky.

They were Xeelee. The Northern was surrounded.

Spinner screamed, and slammed her fists against the hyperdrive waldo.

The ’fighters moved through electric-blue cosmic string like birds through the branches of a forest. There were so many of them in this era. They were cool and magnificent, their nightdark forms arrayed deep into space all around her. Lieserl stared at the swooping, gliding forms, willing herself to see them more clearly. Had any humans ever been closer to Xeelee than this?

The Xeelee moved in tight formation, like bird-flocks, or schools of fish; they executed sudden changes of direction, their domain wall wings beating, in squads spanning millions of miles — absolutely in unison. Now Lieserl saw how ’fighters should be handled, in contrast to Spinner’s earnest, clumsy work. The nightfighters were sculptures of space-time, with a sleek beauty that made her shiver: this was baryonic technology raised to perfection, to a supreme art, she thought.

She was struck by the contrast between this era and the age of devastation — of victory for the photino birds — to which the Northern had first brought them. Here, the Ring was complete and magnificent, and the Xeelee, in their pomp, filled space. Already, she knew, the final defeat was inevitable, and the Xeelee were, in truth, huddling inside their final redoubt. But still, her heart beat harder inside her as she looked out over this, the supremacy of baryonic life.

The overlapping lengths of string slid down, smoothly, past the lifedome, as the Northern climbed. The nightfighters swooped like starlings through the string, and around the Northern — no, Spinner realized suddenly; the nightfighters were flickering across space.

“They’re using their hyperdrive,” she breathed.

Yes. Poole stared up at the nightfighters, his lined face translucent. And we’re hyperdriving too. You’re pushing it, Spinner; we’ve never tried jumps of this scale, even in test. Do you know how fast you’re traveling? Ten thousand light years with every lump… But even so, the Xeelee are easily keeping pace with us.

Of course they are, Spinner thought. They are Xeelee.

These ’fighters could have stopped the Northern at any time — even destroyed it. But they hadn’t.

Why not?

The ship was rising high above the plane of the Ring. The tangle of string fell away from the foreground, and she could see easily now the million-light-year curve of the structure’s limb. And at the heart of the Ring, the singularity seemed to be unfolding toward her, almost welcoming.

The Xeelee ’fighters rose all around her, like leaves in a storm. They can’t believe we’re a threat. I guess humans never were a threat, in truth. Now, it’s almost as if the Xeelee are escorting us, she thought.

“Lieserl,” she said.

“I hear you, Spinner-of-Rope.”

“Tell me what in Lethe’s name we’re doing.”

“You’re taking us out of the plane of the Ring…”

“And then?”

“Down…” Lieserl hesitated. “Look, Spinner, we’ve got to get away from the Xeelee, before they change their mind about us. And we’ve nowhere else to run, not in all of the Universe.”

“And this is your plan?” Spinner was aware of the hysteria in her own voice; she felt fear spread through her stomach and chest, like a cold fluid. “To fly into a singularity?”

Mark punched his thigh. “I was right, damn it,” he said. “I was right all along.”

The tension was a painful presence, clamped around Louise’s throat. “Damn it, Mark, be specific.”

He turned to her. “About the significance of the radio energy flux. Don’t you see? The photino birds have manufactured this immense cavity, of stars and smashed-up galaxies, to imprison the Ring.” He glanced around the skydome. “Lethe. It must have taken them a billion years, but they’ve done it. They’ve built a huge mirror of star stuff, all around the Ring. It’s a feat of cosmic engineering almost on a par with the construction of the Ring itself.”

“A mirror?”

“The interstellar medium is opaque to the radio energy. So each radio photon gets reflected back into the cavity. The photon orbits the Ring — and on each pass it’s super-radiant amplified, as Lieserl described, and so sucks out a little more energy from the inertial drag of the Ring’s rotation. And then the photon heads out again… but it’s still trapped by the galaxy mirror. Back it goes again, to receive a little more amplification… Do you see? It’s a classic example of positive feedback. The trapped radio modes will grow endlessly, leaching energy from the Ring itself…”

“But the modes can’t grow indefinitely,” Morrow said.

“No,” Mark said. “The process is an inertial bomb, Morrow. All that electromagnetic pressure will build up in the cavity, until it can no longer be contained. And in the end — probably only a few tens of millennia from now — it will blow the cavity apart.”

Louise glanced around the sky, seeing again the smooth distribution of galaxies she’d noted earlier. “Right. And, in a hundred thousand years, the Northern will fly right into the middle of the debris from that huge explosion.”

Now the ship had sailed high above the plane of the Ring; Louise could see the whole structure, laid out before her like the rim of a glimmering mirror, with the sparkle of the singularity at its heart.

Lieserl said, “Louise, the hostile photino bird activity we’ve noted before — the direct assault on the Ring itself with lumps of matter — is spectacular, but Mark’s right: this radio bomb trick is what will truly bring down the Ring.” A subtle smile played on her lips. “It’s damn clever. The birds are draining the Ring itself, drawing energy out of the gravitational field using inertial drag. They’re going to use the Ring’s own mass-energy to wreck it.”

Subvocally, Louise checked her chronometer. Less than twenty minutes had elapsed since Mark and Lieserl had ordered Spinner to start moving the ship, but already they must have crossed eight million light-years — already they must be poised directly above the singularity.

“Mark. Where are we going?”

Poole, evidently trying to calm Spinner, told her what would happen to the nightfighter as it approached the disc singularity.

A timelike trajectory could reach the upper surface of the disc, Poole told her. A ship could reach the plane of the singularity. But — so said the equations of the Kerr metric — no timelike trajectory could pass through the singularity loop and emerge from the other side.

“So what happens? Will the ship be destroyed?”

No.

“But if the ship can’t travel through the loop — where does it go?”

There can be no discontinuity in the metric, you see, Spinner-of-Rope. Poole hesitated. Spinner-of-Rope, the singularity plane is a place where universes kiss.

“Lethe,” Louise said. “You’re planning to take us out of the Universe?”

Mark swiveled his head toward her, unnaturally stiffly; the degradation of the image of his face — the crawling pixel-defects, the garish color of his eyes — made him look utterly inhuman. “We’ve nowhere else to run, Louise. Unless you have a better idea…”

She stared up at the singularity. The AIs, working together at inhuman speed, had come up with a response to this scenario. But are they right? She felt the situation slipping away from her; she tried to plan, to come to terms with this.

Lieserl said drily, “Of course, timing is going to be critical. Or we might end up in the wrong universe…”

Morrow clung to his scooter, his eyes wide, his knuckles bloodless. “What in Lethe’s name are you talking about now?”

Mark hesitated. “The configuration of the string is changing constantly. It’s a dynamic system. And that’s changing the topology of the Kerr metric — it’s changing the basis of the analytical continuation of space through the singularity plane…”

“Damn you,” Morrow said. “I wish you’d stick to English.”

“The singularity plane is a point at which this Universe touches another smoothly. Okay? But because of the oscillations of the Ring, the contact point with the other universe isn’t a constant. It’s changing. Every few minutes sometimes more frequently — the interface changes to another continuation region — to another universe.”

Morrow frowned. “Is that significant for us?”

Mark ran a hand through his hair. “Only because the changes aren’t predictable, either in timing or scope. Maybe the changes cycle round, for all I know, so if we wait long enough we’ll get a second chance.”

“But we don’t have time to wait.”

“No. Well, we’re not exactly planning this… We won’t be able to choose which universe we end up in. And not every universe is habitable, of course…”

Louise pressed her knuckles to her temples. Good point, Mark. We’ve decided to commit ourselves to crashing out of our Universe, and we have half the Xeelee nightfighters in creation on our tails already… and now you bring me this. What am I supposed to do about it?

“Tell me what you see through there right now,” she said. “Tell me about the universe on the other side of the Kerr interface.”

“Now?” Mark looked doubtful. “Louise, you’re asking me to come up with an analysis of a whole cosmos — based on a few muddled glimpses — in a few seconds. It’s taken all of human history even to begin a partial — ”

“Just do it,” she snapped.

He studied her briefly, his expression even. “Some of the twin universes feature a degree of variation to our physical laws. That’s no great surprise; the constants of physics are just an arbitrary expression of the way the symmetries at the beginning of time were broken… But even those universes with identical laws to ours can be very different, because of changed boundary conditions at the beginning of time — or even, simply, from being at a different stage of their evolutionary cycles to ours.”

“And in this particular case?” she asked heavily.

He closed his eyes. Louise could see that stray pixels, yellow and purple, were again migrating across the Virtual images of his cheeks. His eyes snapped open, startling her. “High gravity,” he said.

“What?”

“Variation of the laws. In the neighboring universe, the constant of gravity is high — enormously high — compared to, uh, here.”

Morrow looked nervous. “What would that mean? Would we be crushed?”

More pixels, glitches in the image, trekked across Mark’s cheeks. “No. But human bodies would have discernible gravity fields. You could feel Louise’s mass, Morrow, with a pull of about half a gee.”

Morrow looked even more alarmed.

“Stars could be no more than a mile wide, and they would burn for only a year,” Mark said. “Planets the size of Earth would collapse under their own weight immediately…”

Lieserl frowned. “Could we survive there?”

Mark shrugged. “I don’t know. The lifedome would implode immediately under its own weight. We’d need to find a source of breathable air, and fast. And we’d have to live in free fall; any sizeable mass would exert unbearably high gravitational forces. But maybe we could make some kind of raft of the wreckage of the Northern…”

Lieserl looked up into the singularity plane, and her expression softened. “We know there have been human assaults in the Ring — like the neutron star missile. So perhaps we are not the first human pilgrims to fall through the Ring. Mark, you said the bridge to the other universe goes through cycles. I wonder if there are humans on the other side of that interface even now, clinging to rafts made from wrecked warships, struggling to survive in their high-gravity world…”

Mark smiled; he seemed to be relaxing. “Well, if there are, we won’t meet them. That continuation has closed off; a new one is opening… Wherever we’re going, it won’t be there.”

Louise glanced up at the false-color sky. “…I think it’s time to find out,” she said.

The Northern reached the zenith of its arc, high over the plane of the Ring.

Spinner felt as if she were suspended at the top of some huge cosmic tree, a million light-years high. The ship was poised above the singularity’s central, glittering pool of muddled starlight, and beyond that, at the edge of her field of view, was the titanic form of the Ring itself.

The flock of nightfighters hovered in a rough cap around her and above her, their wings spread. The ’fighters were sharp, elegant forms, filling space.

Spinner-of-Rope closed her hands over the hyperdrive waldo.

Now, it was like tumbling out of the tree.

The nightfighter fell through space, covering ten thousand light-years every second.

The singularity is a gateway to other universes, Michael Poole said. Who knows? — perhaps to better ones than this.

In fact, Poole told her, there had to exist further gateways, in the universe beyond, to still more cosmoses… He painted a picture of a mosaic of universes, connected by the glowing doorways of positive and negative Kerr singularities. It’s wonderful, Spinner-of-Rope.

Spinner stared down at the singularity. “Is this what they intended? Did the Xeelee mean to construct the singularity as a gateway?”

Of course they did. Why do you think they made the singularity so damned big?… So that ships could pass through it, without being destroyed by tidal forces from the singularity thread.

Spinner-of-Rope, this is the Xeelee’s most magnificent achievement. I would have liked to tell you some day how this Ring was built… how the Xeelee returned through time and even re-engineered their own evolution, to give themselves the capabilities to achieve this.

“You would have liked to tell me… ?”

Yes. Poole sounded sad. Spinner, I’m not going to get the chance… I can’t follow you.

“What?”

It was as if she descended through an immense tunnel, walled by the distant, irrelevant forms of blue-shifted galaxies. The singularity was the starlit open base of that tunnel, out of which she would fall into -

Into what?

Still, the starling flocks of nightfighters swirled around the ship.

“You know,” she said, “the Xeelee could have stopped us at almost any point. I’m sure they could destroy us even now.”

I’m sure they could.

“But they haven’t.”

Perhaps they are helping us, Spinner-of-Rope. Maybe there is some residual loyalty among the baryonic species, after all.

“…Spinner-of-Rope.”

“Yes, Lieserl.”

“Listen to me. The trip through the singularity is going to be — complicated.”

“Oh, good,” Spinner said drily.

“Spinner, the spacetime manifold around here isn’t simple. Far enough out the singularity will attract us — draw us in. But close to the plane of the singularity, there is a barrier of potential in the gravitational field.”

She sighed. “What does that mean?”

“…Antigravity, Spinner-of-Rope. The plane will actually repel us. If we don’t have enough kinetic energy as we approach the plane, we’ll be pushed away: either back to the asymptotically flat regions — I mean, to infinity, far from the plane — or else back into the zone of attraction. We could oscillate, Spinner, alternately falling and being repelled.”

“What happens on the other side? Will we be drawn back into the plane?”

“No.” Lieserl hesitated. “When we pass through the plane, there is a coordinate sign change in the metric… The singularity will push us away. It will hurl us on, deep into the new universe.”

“So what do I have to do?”

“To get over the potential barrier, we need to build up our kinetic energy before we hit the plane of the singularity. Spinner, you’re going to have to operate your discontinuity drive in parallel with the hyperdrive. The fractions of a second between jumps, when we’re in normal space, will be enough to let us begin our normal-space acceleration.”

Spinner felt sweat trickle over her face, pooling under her eyes behind her spectacles. She was afraid, suddenly, she realized: but not of the singularity, or what might lie beyond, but of failing. “That’s ridiculous, Lieserl. How am I supposed to pull that off? What am I, a spider-monkey?”

Lieserl laughed. “Well, I’m sorry, Spinner-of-Rope. We’re making this up as we go along, you know…”

“I can’t do it.”

“I know you can,” Lieserl said calmly.

“How do you know?”

Lieserl was silent for a pregnant moment. Then she said, “Because you have help. Don’t you, Spinner-of-Rope?”

And Spinner felt the warm hands of Michael Poole close over hers once more, strong, reassuring.

The discontinuity-drive wings unfurled behind the hulk of the lifedome, powerful and graceful.

“If it’s any consolation, Spinner, we’ll be a spectacular sight as we hit the plane,” Lieserl said. “We’ll shed our Kerr plunge radiation in a single burst of gravity waves…”

The singularity plane was widening; it was a disc, filled with jumbled starlight, opening like a mouth.

“Michael, will there be photino birds, in the new universe?”

I don’t know, Spinner.

“Will there be Xeelee?”

I don’t know.

“I want you to come with me.”

I can’t. I’m sorry. The quantum functions which sustain me don’t traverse the plane of the singularity.

The Xeelee ’fighters swirled around her cage, graceful, their nightdark wings beating. They filled space to infinity, magnificent here at the heart of their final defeat. The plane of the singularity was a sea of silver light below her.

The construction material of her cage, of the wings, began to glow, as if white hot.

Michael Poole turned to her, and nodded gently. The construction-material light shone out through his translucent face, making him look like a sculpture of light, she thought. He opened his mouth, as if to speak to her, but she couldn’t hear him; and now the light was all around him, engulfing him.

“Come with me!” she screamed.

And now, suddenly, dramatically, the singularity was here. Its rim exploded outwards, all around her, and she fell, helplessly, into a pool of muddled starlight.

She cringed into herself and clutched her hands to her chest; her worn arrowhead dug into her chest, a tiny mote of human pain.

33

The lifedome was plunged into darkness.

The jungle sounds beneath Louise were subdued, as if night had fallen suddenly… or as if an eclipse had covered the Sun.

The lifedome groaned, massively; it was like being trapped inside the chest of some huge, suffering beast. That was stress on the hull: the coordinate change, as the ship had crossed the singularity plane.

We have entered a new cosmos, then. Is it over? Louise felt like an animal, helpless and naked beneath a storm-laden sky.

Lieserl had spoken of how all of human history was funnelling through this single, ramshackle moment. If that was true, then perhaps, before she had time to draw more than a few breaths, her own life — and the long, bloody story of man — would be over.

…And yet the sky beyond the dome wasn’t completely dark, Louise saw. There was a mottling of gray: elusive, almost invisible. When she stared up into that colorless gloom, it was like staring into the blood vessels she saw when she closed her own eyelids; she felt a disturbing sense of unreality, as if her body — and the Northern, and all its hapless crew — had been entombed, suddenly, within some gross extension of her own head.

There was a rasp, as of a match being struck. Louise cried out.

Mark’s face, dramatically underlit by a flickering flame, appeared out of the gloom. Lieserl laughed.

“Lethe,” Louise said, disgusted. “Even at a time like this, you can’t resist showing off, can you, Mark?”

“Sorry,” he said, grinning boyishly. “Well, the good news is we’re all still alive. And,” more hesitantly, “I can’t detect any variation of the physical constants from our own Universe. It looks as if we may be able to survive here. For a time, at any rate…”

Lieserl snorted. “Well, if this universe is so dazzlingly similar to our own where are the stars?”

Now the lifedome began to lighten, as Mark kicked in image enhancing routines. It was almost like a sunrise, Louise thought, except that in this case the spreading light did not emerge from any one of the lifedome’s “horizons”; it simply broke through the muddy darkness, right across the dome.

In a few heartbeats, the image stabilized.

There were stars here, Louise saw immediately. But these were giants — and not like the bloated near-corpse which Sol had become, but huge, vigorous, brilliant white bodies each of which looked as if it could have swallowed a hundred Sols side by side.

The giants filled the sky, almost as if they were jostling each other. Several of them were close enough to show discs, smooth white patches of light.

Nowhere in her own Universe, Louise realized, could one have seen a sight like this.

Beside her, Lieserl sighed. “Uh-oh,” she said.