STARFALL

Stephen Baxter

AD 4771

Starfall minus 49 years

Between Sol and Alpha Centauri

Minya and Huul stood together on the comet's observation deck, in freefall, gently embraced by smart webbing. Beneath their feet lay the bulk of the comet nucleus, a fifty-kilometres-deep frozen ocean of dirty water ice. Above their heads was the fine carapace of the observation blister, and above that nothing but stars, a field of jewels.

Huul drank in the view, for he knew he had only moments left to enjoy it. Already the bots were working at the fringe of the window, coating it over with an authentic-looking layer of comet frost. When the blister was covered altogether it would be dismantled, this outer level of decking collapsed, and the human crew confined to a huddle of chilly chambers deep in the comet's heart

And Huul's son, yet unborn, would never see the stars at all—not until he was older than Huul was now. Huul, with a spasm of regret, put his hand on his wife's belly, trying to feel the warmth of the baby within.

Minya knew what he was thinking. She was tougher than he was, but more empathetic too. "I know," she said. "We are sacrificing a great deal—and we are imposing that sacrifice on our son. But his son will thank us."

Huul grunted. "Perhaps. But he might be the one doing the fighting, by the time we get to Sol."

"I know, I know. Let's just enjoy the view, while it lasts."

He gazed out at the stars. "Isn't it strange to think that whether you live in Alpha system or Sol system, the stars you see are much the same? We have that much in common at least."

"True. With a couple of exceptions." And she pointed back the way they had come, back to Alpha Centauri, which even from this immense distance showed as a clear double sun.

And when Huul looked the other way he saw a compact constellation. From Earth it was a W shape, known as Cassiopeia, one of the most easily recognisable of the star figures—but from Alpha, and from here, there was an extra star to the left of the pattern, turning the constellation into a crude scribble. That star was Sol, bright but not exceptionally so, the first star of mankind.

"It doesn't look much, does it?" Minya murmured. "Just a lantern in the sky. But that is the seat of the Shiras, the source of all our trouble."

"And that," said Huul with mordant humour, "is where you and I will die."

"You mustn't talk like that," Minya snapped. "The Starfall project is already magnificent, Huul. Magnificent!"

She was right, Huul knew. The starborn's rebellion against Earth had already been decades in the planning. The supplying of this comet-ship by lightsail out of Alpha, about as covert an operation as could be mounted on such a scale, had alone taken decades. And now the comet had been nudged onto a path that would take it sailing into Sol system in less than five decades, a trajectory intended to make it appear that this was just another long-period comet making an entirely natural visit to its parent star. But a crew of saboteurs would be huddled in its icy heart, locked into a tightly closed miniature ecology, not allowing as much as a stray erg of heat to leak to space to betray their presence.

Minya said, "The earthworms won't know we're among them until we're bright in the skies of Earth. And then we'll see what's what. Remember, Huul. We will be the Second Wave of the Starfall assault, second only to the smart plague. When we have helped cut away the tyranny of the Shiras at the root, to us will accrue much glory—and to our descendants for all time, as far as mankind journeys in time and space."

But the labouring bots were almost done in frosting over the observation dome. And, Huul thought, I may die without ever seeing another star.

Minya tugged at his hand. "Come on. We've work to do."

AD 4801

Starfall minus 19 years

Tau Ceti

The flitter from the Facula arrowed towards the centre of the daylit face of the planet. Tau Ceti II was a small, warm, watery world, all but drowned by a vast ocean, and habitually swathed in cloud—and now, according to imperial intelligence, host to an unauthorised human colony.

"There's definitely something wrong," Pella said.

Stillich turned to his First Officer. Pella sat crammed in with the assault squad in the translucent hull of this intrasystem flitter. She was peering obsessively at a diorama of their target. Stillich glanced around at his marines, sitting in their smartsuits, the sunburst sigil of the Empire of Sol on their breasts. He got grins back, but he could sense their nervousness, and Pella's fretting wasn't helping.

The journey out from Sol had been over five years subjective, more than thirteen objective. This was Stillich's first interstellar jaunt under his own command, and he understood that his primary task during the cruise out had been to keep his crew interested, with a training programme half a decade long intended to sharpen them for this very moment, the planetfall. Stillich, in fact, had already started to turn his attention to the return journey, when another five-year programme would prepare the crew for the culture shock of their return.

To Stillich the journey itself had been the principal challenge. He had not expected the mission itself, the subduing of a ragged bunch of second-hand colonists from Alpha, to present any problems. But now here was Pella with her analyses, mucking up morale, right at the climax of the mission.

He murmured to her, "There's no evidence of any threat to us from these ragged-arsed colonists, Number One."

Pella was bright, but she was young, at thirty a decade or so younger than Stillich. And she had a strong, prickly sense of herself. "No, sir. But what we're seeing doesn't make sense. The colony looks wrong. Half-dismantled, rebuilt. Look." She showed him hastily processed drone images of circular landforms, evidence of abandoned structures. "There can't be more than a few thousand people on the planet. Why would you move?"

Stillich shrugged. "Weather. Seismic problems. There's any number of reasons why you might get your first location wrong—"

"These are interstellar colonists, Captain. They're unlikely to be so foolish. I'd be happier if we were going into this situation better informed."

So would I, Stillich thought, but he wasn't about to say so before his troops. He forced a grin. "We're just going to have to have our wits about us when we land. Right, lads?"

He was rewarded with a muted cheer. "You said it, skip."

A gong's low chime, the call to prayer, filled the cabin of the little flitter. The men had their solar amulets fixed outside their suits to their wrists, and they consulted these now, shifting in their seats so they could face towards Sol. Soon the murmured prayers began.

Stillich turned too. He knew where Sol was, actually; he could find it from the constellations, distorted by this translation to Tau Ceti. But nearly twelve light years from Earth it was tricky to pick out the home star. That, of course, was proclaimed by the Shiras as the natural limit to the human dominion—the Empire of Sol was to be that bubble of space close enough that you could see the home star with the naked eye, and so be able to pray to its munificence.

But Stillich knew that the Shiras' control depended on more practical considerations.

The Facula was a GUTdrive starship. 'GUT' stood for 'Grand Unified Theory'. The ship was essentially a plasma rocket, its exhaust propelled by a phase-transition energy that had once driven the expansion of the universe itself. After a thousand years this was still the peak of mankind's interstellar technology. But the Facula was a sublight ship. And a human navy forever contained by lightspeed had a certain natural reach.

The Facula was capable of sustaining a one-gravity acceleration for years, indeed decades. Including time for acceleration and deceleration, she could reach Alpha Centauri in a mere forty-three months subjective, and Tau Ceti in a little more than five years. But in flight, thanks to relativistic time dilation, the crew's heartbeats were slowed, their lives extended, and the voyages as measured by the external world were longer—it was fourteen years to Tau Ceti, as recorded on Earth.

And it was this rigidity of relativistic time that set the true limits on the Shiras' interstellar grasp. The young crew of the Facula were soldiers of the Empress; they would fight for Shira XXXII if there was a reasonable promise that they would be brought home. But it had been discovered that if any longer than a generation elapsed back home that promise was broken, loyalty dissipated by an excess of culture shock; any longer a flight became an emigration. AS anti-ageing technology made no difference, for this limit was a function of human consciousness, not significantly altered by extended lifespans—and besides, all soldiers were young, as they had always been. Even using sleeper pods would not help; that could only cut down the subjective flight time, not the objective interval.

Given such fundamental limits, Tau Ceti was about as far as the Shiras could ever extend their empire. But it was enough, for no less than nineteen star systems, plus Sol, lay within that limit of loyalty. And this mission was proof that the Shiras enforced their rule right to the boundaries.

The time for prayer was over. The marines folded away their amulets and closed their faceplates.

The flitter ducked into the murky air of Tau Ceti's second world.

They landed briskly on the perimeter of the largest human colony, close to the shore of an island-continent. The hull cracked open, and the marines spilled out to set up a secure perimeter around the flitter. Glowing drones flooded the air, and bots began digging trenches.

Stillich peered about curiously. A lid of cloud turned the pale light of Tau Ceti to a dull grey. They had apparently come down in a field, where Earth vegetation drew sustenance from the nutrients of an alien soil, no doubt heavily nano-worked. But plants of a more exotic sort, with leaves of purple and silver-grey, clustered among the green. There were structures on the low horizon, unprepossessing, just shacks, really. People stood before the shacks, adults with hands on hips, a couple of children. They watched the marines with apparent curiosity but no sign of fear or deference.

Although Tau Ceti was actually the most sun-like of all the stars within the Empire of Sol, such were the distracting riches of Alpha system that only one serious colonising expedition from Earth had been mounted here—and that ship had been reassigned to a more urgent mission and had never been heard of again.

Evidently all that had changed.

"Walk with me," Stillich said to Pella. He set off towards the shacks, and Pella followed. Marines shadowed them, weapons in hand. "What a dump," Stillich said. "This world, this dismal farm, those shacks. To come all this way to live like this."

Pella, characteristically, was peering into her data desk, rather than studying the world around her. "They will be grateful we have come to save them, sir ... " She stopped suddenly, a hundred paces short of the shacks. "Look." She pointed to a kind of earthwork, circular, just a system of ditches and low ramparts cut into the ground. "This is what I saw from the drones. Can you see the way the ground has been flattened within the perimeter, as if something has been set down here? And over there—" She pointed. "Residual traces of radioactivity."

"They came here in a GUTship," Stillich said.

"Yes, sir. They brought it down and dismantled it. They lived in the lifedome, just here, and used the GUTdrive for power."

"And now it's all gone."

"And quite recently too—l mean, a few decades ... "

A woman approached them. Short, squat, she had the heavy shoulders and big hands of a farmer. She was perhaps forty, though with AS tech she could be any age. She wore a facemask and a small air pack, but no other environmental protection. She grinned, showing good teeth, and said something in a liquid dialect that Stillich's systems began to translate for him.

He waved that away. "Speak Earthish," he snapped.

The woman eyed him, perhaps deciding whether to obey him or not. "I said, 'Welcome to Home'."

"What an original name," sneered Pella.

"You don't need to wear those fancy suits. An air mask will do. We long since nanoed out any nasties. A couple more generations and—"

"You should not be here," Stillich said. "This colony is unauthorised."

"Well, you'll have to take that up with my grandfather, who came here from Alpha system when Footprint got a bit too full for his liking."

Pella looked around. "Where is your grandfather?"

"Dead these forty years. Don't you want to know my name?"

Pella snapped, "Your name is irrelevant. The GUTships you used to get here were the property of the Empire of Sol."

The farmer laughed again.

Pella, her temper quick, her ego strong, raised her arm.

Stillich touched her shoulder to restrain her. He said, "Woman—you broke up your transport ship to build your first colony here." He gestured. "You lived in the lifedome. You used the GUT engine for power. And yet these things are gone."

"You reassembled the ship, that's obvious," Pella said. "And other vessels. But why? Where have you sent them?"

The woman responded with another grin, surly.

This time Pella did strike her, using her elbow to dash the woman to the ground. Marines rushed in, weapons raised. "Take her," Pella said. "And her children. Torch this place. We will have five years to empty her of all she knows, before we reach Sol system once more."

As the marines closed on the shack-like farm buildings, Stillich considered intervening. This was no way to run an empire, this use of brute force. But he didn't want to contradict his First Officer in front of the marines; the fate of this farmer wasn't important enough for that.

Pella stood with him, breathing hard, still angry. "Actually I'm not sure how concerned we should be, sir. Now I stand here, amid the rubble of these colonists' petty dreams—if some of them have taken their GUTships off into the dark, so what? There's no G-class star until you get to Delta Pavonis, eight more light years out from Sol. Too far away to bother us. Why should we care?"

But it wasn't obvious to Stillich that this new jaunt had been outwards at all.

Human space was sparsely settled, save for Sol system itself, and Alpha system. And if you weren't to travel outwards, a return journey to Alpha was by far the most likely destination. Stillich had visited Alpha himself, on the two previous interstellar missions of his career. It was a big, sprawling, increasingly crowded system—potentially richer in resources even than Sol system itself. And as a junior officer he had detected signs of rebelliousness there, signs that the Alphans were chafing under the yoke of the Shiras' taxes and political control, signs he had dutifully reported to his superiors.

It might be harmless. Maybe the GUTships had gone back to pick up another cadre of colonists for Tau Ceti. Or maybe not.

"Tidy up here," he said to Pella. "But do it fast; the sooner we get out of here the better. I'm going back to the Facula to send a message to Earth." Which itself would take twelve years to get there. He turned and stalked back to the flitter.

Pella called, "Sir, the colonists—are they to be permitted to stay?"

He considered. "No." That was the tidiest solution. "We have sleeper pods enough to transport these ragged villagers back to Sol. Get on with it, Pella. And avoid excessive violence."

"Sir."

Stillich heard screaming from the farmer's children. He did not look back.

AD 4814

Starfall minus 6 years

Armonktown, Footprint. Alpha System

Suber's youngest son, little Suber, Su-su, called him out of the house. "Dad, come see. I think there's another one up there, another GUTship!"

Suber had been helping Fay prepare the evening meal. Fay, at thirty, Suber's second wife, was nearly seventy years Suber's junior, though thanks to his AS treatment she actually looked a little older. She grinned across at him. "Go. You can help me for the next hundred years; Su-su will only be seven years old once. Go!"

So he grabbed his coat and let his son drag him out of the house, down the darkened street towards the park, where, away from the streetlights of Armonktown, you got the best view of the sky. But Suber was soon winded as he tried to keep up with Su-su. He had been born on Earth—though Su-su did not know that, and nor did Fay, and they never would-and even after seven decades here and extensive nano treatments Footprint's stronger gravity still hung heavy as a lead coat.

They came to the park. It was a fall evening, and the dew lay on the grass and the roses' thorns, and glistened on the blisters of the rope-trees, a native species allowed to prosper in their own little bubbles of Footprint air inside the town dome. And there on the grass, little Su-su turned his button face up to the sky. "See, dad?"

Suber looked up.

The sky was crowded and complex. From Footprint, a world of Alpha A, sun B was a brilliant star in the sky, closer to Alpha A than planet Neptune was to Sol, bright enough to cast sharp shadows; on this world there were double sunrises, double sunsets, strange eclipses of one star by the other. And there was a line of light drawn across the sky: dazzling, alluring, that zodiacal gleam was the sparkle of trillions of asteroids. The mutual influence of A and B had prevented the formation of large planets; all the volatile material that had been absorbed into Sol's great gas giants was here left unconsolidated, asteroids drifting in huge lanes around the twin stars. Footprint's sky was full of flying mines.

But what interested Su-su wasn't the natural wonders of the sky but the signs of human activity. He pointed with his small finger, to a cloud of light slivers not far from the zenith. "Can you see, dad? I can count them. One two three four five seven twelve! And there's a new one since they passed over yesterday."

"Your eyes are better than mine," Suber said. "But, you know, I think you're right ... "

The splinters of light were ships: GUTships, a veritable fleet of them in a medium-altitude orbit over Footprint. Under magnification they showed the classic design, lifedome and GUTdrive pod connected by a spine kilometres long. Somebody was assembling an orbital armada—and presumably bringing in the ships even from other star systems, for there was no facility to construct GUTships anywhere save Sol system itself.

Suber had heard no announcement about this mustering, seen no news source refer to it, even though it was clearly visible to everybody. He wondered why no imperial official had been out to inspect it. He had even considered trying to get some message to the Empress's court himself. But it was unlikely in the extreme he'd be able to do this without blowing his personal cover.

It was while he was thinking of Earth, oddly, in that quiet moment with his son, that his life on Footprint ended.

The voice behind him was soft. "Densel Bel?"

He turned, unthinking. "Yes?" And then, "Ah." He had responded to a name he hadn't heard spoken since he left Earth.

The man facing him was dressed entirely in black, some fabric so dark it seemed to absorb the light from the sky; he was a shadow, even his face concealed.

Densel-Suber did not dare glance around for Su-su. "May I say goodbye to my son?"

"No." The man pointed a finger.

There was a shock, not of pain, but of cold. He felt his heart stop before he hit the ground.

And when he could see again, he was enclosed by walls, in a room, bathed in bright light. He winced, and lifted a hand to shield his eyes. And he staggered, for he was standing, held by a mesh web.

Somebody handed him a beaker of liquid. He drank, and felt warmth course through his system.

A man stood before him. A broad face, aged with no apparent recourse to AS, stocky build, crop of grey hair. Densel thought he recognised him. Others stood by—a young woman at this man's side, perhaps a daughter. Densel wondered if they were armed.

The room had a single window that opened on blackness. The smart webbing filled the room, holding the people unobtrusively. He was in microgravity then, in orbit perhaps.

The man studied him. "Are you all right, Densel Bel? You were injected with a nano anaesthetic. I hope it didn't hurt; you were obviously unprepared in the conventional medical way."

"I'm fine." He drew a breath. His chest ached vaguely; he wondered if he had had some minor heart attack. "You know who I am."

"Obviously. And you know me, don't you?"

"You are Flood. Ambassador to the Empress's court." Flood's was one of the more famous faces in the small pool of Alpha cultural life.

"Former ambassador. I retired some years ago. Now I am engaged on other projects."

"I want to speak to my family—"

"You mean the two families you raised on Footprint, to whom you lied all their lives? Forget them, Densel Bel. You are dead to them. They are dead to you. That part of your life is over."

The shock of this abduction seemed to be hitting Densel; if not for the webbing he might have fallen. "For seventy years I have prepared for this moment. Still it is hard."

"You chose your own path. This always lay at the end of it."

"How long have you known?"

"We have known all about you since you came tumbling out of the wreckage of the last Poole wormhole."

Once Alpha and the other colonised star systems had been linked by faster-than-light wormholes, assembled in Jovian orbit, their interfaces laboriously hauled across interstellar distances by GUTships. Seventy years ago Shira XXXII, on ascending to the Construction Material Throne, had ordered the links to be cut.

"I was trained since I was a boy for the task," Densel said. "I knew nothing else but the purpose. I suppose you would say I was conditioned. I should have died when the wormhole collapsed."

"Yes. You are a suicide bomber who failed to die."

"I was stranded on Footprint. Unexpectedly alive, it was as if I awoke. I built a life, an identity—I built a soul. Do you begrudge me that? I have been cut off from my world for seven decades—"

"Your world? Isn't this your world now, a world you have helped build with your skills in exotic-matter engineering, skills developed for destruction put to better use?"

"Why did you not deal with me before?"

"Because we always thought you might be useful. You were doing no harm in the meantime."

Densel frowned. "Who is 'we'?"

"We are a loosely bound, loosely defined group, but with a single clear goal."

"Which is?"

"The liberation of the star born from the tyranny of the Shiras. You were involved in the strengthening of the Empresses' grip. The wormholes were cut so that Earth might be protected from us by a blanket of spacetime, while possessing a near-monopoly on GUTship construction technology. So we can be controlled, forever."

Densel took a breath. "Is the rule of the Shiras so bad? The empire's touch is light—"

"An interstellar empire makes no sense, economically or politically. There is no possibility of meaningful trade save in information; fabrication will always be cheaper than any possible transport. The taxes we pay are punitive, and don't even enrich the Shiras; they only serve to pay for the Navy ships and bases which enslave us. The purpose of the Empire is purely ideological, purely intended to make us bow down before the light of a star so dim and remote that most of us have trouble finding it. And the Empresses' political control is destructive, even when it is not harsh. It hinders our own political development, our exploitation of this system, and the colonisation of others. Even this, however, we might have tolerated, for all empires wither in time."

"But something has changed/' Densel guessed.

"Yes. We believe the latest Shira represents a grave danger to us all. Do you know anything of the court?"

"I met her once," Densel said. "Shira XXXII. She touched my head; she blessed me in Sol's light, before she sent me to die. I learned nothing of her."

"Then you've never heard of metamathematical spaces—of logic pools? Of a man called Highsmith Marsden?"

"No ... "

"Marsden ran secretive experiments more than a thousand years ago. The result of his meddling was the destruction of a moon of Sol VIII."

"Neptune."

"Now we fear that the Empress's meddling with the same technology is liable to cause an even greater danger."

"Even for us, here in Alpha system?"

"Even here," Flood said seriously. "Shira must be stopped."

Densel felt cold, as if his heart were being stopped by nanomachines once more. "You're going to invade Sol system."

"Yes, we're going to invade. We intend to defeat Sol's navies and armies, to occupy the Earth, and to depose Shira herself. We call this programme the Starfall, the falling of the wrath of the stars upon the Earth."

Densel laughed. "You can't be serious. You can't defeat Earth. The starborn number a few tens of thousands. Earth's population is billions."

"We have advantages—the principal one being that nobody has attempted a war on this scale before. And you are honoured, Densel Bel. Because you're going along for the ride. Come to the port." He put an arm around Densel's shoulders. "Can you walk?"

Densel took cautious steps. The smart webbing released and embraced him smoothly, holding him to the floor.

Beyond the window GUTships hung in space like toys. Flitters moved between the great vessels, and bots and humans worked on scuffed lifedome bubbles and balky GUT drive pods. This clumsy armada drifted over the nightside face of Footprint.

"So this is how you're going to defeat Shira XXXII," he said bitterly. "With these rusty scows."

Flood was unfazed. "Our assault will proceed in four waves, which will arrive at Sol system more or less simultaneously. The First Wave is a lightspeed viral attack and will actually be the last to be launched. The Second Wave, a deeply-sublight stealth assault, was assembled and launched some decades ago. These GUTships constitute the Third and Fourth Waves. The Third Wave ships are weapons platforms and troop carriers. I myself will be embarking on the Freestar, the lead ship, very soon.

"And you, my friend, will be aboard one of the Fourth Wave ships, which we call the Fists. You don't need to be launched for another nine months. You'll catch us up, you see."

"How? By accelerating at higher gravities?"

"Oh, no. It's just that you won't be slowing down."

Densel Bel stared at him. "Why put me on this ship of fools?"

"I told you. We always thought you were useful. You'll have plenty of time to think it over in flight—more than two years subjective, in fact. But I don't have to tell you any more now. You see that, don't you?"

"Yes," Densel said. He did see it. For effectively, as Flood had said, his life was over, his ability to make choices about his future already gone.

"Now let's get on with it. There's only a few more hours before the Third Wave ships light up. My daughter, Beya," he indicated the young woman at his side, "will take you to the ship that is to be your home for the rest of your life ... "

Densel gazed down on the planet's sparse lights helplessly, wondering if even now Su-su and Fay were looking up at him.

AD 4815

Starfall minus 4 years 8 months

Sol System

Stillich's orders were clear. As soon as the Facula docked at Port Sol, he was to make his way direct to Earth and report to the imperial court, to expand on the reports he had been narrowcasting from space.

But as he passed through Port Sol he could not help notice what had become of it during his twenty-seven-year absence.

Port Sol, mankind's greatest GUT-technology interstellar harbour, was a Kuiper object: a two-hundred-kilometre ball of friable rock and water-ice that circled the sun beyond the orbit of Pluto, along with uncounted companions. As Stillich's flitter dipped low over a crystalline landscape, on its way to the Interface to Earth, the work of humanity was clear. The primordial ice was gouged by hundreds of craters: deep, regular, these were scars left after the supply of the great interstellar GUTships with ice for reaction mass. There were buildings too, housing for dock workers and ship crews, even a couple of hotels, with domes, pylons and arches exploiting the microgravity. But many of the buildings were closed, darkened. Thin frost coated their surfaces, and some of the domes were collapsed. GUTships hung all around the little world, as if jostling for a place to land.

"Lethe," said Pella. "Something bad happened here."

Now the flitter lifted away from Port Sol, and a cluster of wormhole Interfaces swam towards them, giant tetrahedra built of struts of electric-blue light. The wormholes to the stars had been cut, but the ancient fast-transit routes within Sol system itself still connected Port Sol to the rest of the system. Without hesitation Stillich's flitter thrust itself towards the largest of the wormholes, the gateway to Earth, only minutes away. Pella watched nervously.

Stillich was paging through a data desk, looking for information about Port Sol. "Some kind of 'industrial accident', it says here. A GUTship blew up in dry dock. It's put the construction facilities out of action for a decade, and the maintenance facilities are stretched."

One shimmering triangular face grew huge in their view, an electric-blue frame that swallowed up the flitter. The ship shuddered, buffeted, and blue-white light flared around them.

"And guess where that GUTship came from? Alpha. Of course Alpha is a pretty common destination. It might be coincidence. Or it might not. Get some images, Pella, and dig around in the data mines. See what else you can find on this."

"Sir ... "

Stillich looked up. Pella was gripping her data desk, trying not to cower.

The wormhole was a throat in space and time: a region of stress, of immensely high curvature, lined with exotic matter throughout its length. Now fragments of light swam from a vanishing point directly above their heads, swarmed down the spacetime walls and, fading, shot down over the horizon. This was radiation generated by the unravelling of stressed spacetime, deep in the throat of the flaw. There was a genuine sensation of speed, of uncontrollable velocity.

Stillich took pity on Pella, and let her endure the rest of the transit without making her work.

The flitter burst out of the destination Interface, amid a shower of sparks and exotic particles. Now they were among another cluster of wormhole terminuses, even bigger, even more crowded with jostling ships. This was Earthport, the system's central transit hub, positioned at a stable Lagrange point in lunar orbit. In contrast to the desolation of the outer system, Stillich had a powerful, immediate impression of bustle, prosperity, activity.

And there, beyond the drifting tangle of exotic-matter tetrahedra, Stillich made out Earth itself, her face broad and lovely, like a slice of the sky.

The flitter shot out of the mob of ships around Earthport, swept through a layer of defence stations, and within minutes was beginning its descent.

Huge fusion stations sparkled in their orbits above green-blue oceans. The planet itself was laced with lights, on land and sea. And in the thin rim of atmosphere near the north pole Stillich could just make out the dull purple glow of an immense radiator beam, a diffuse refrigerating laser dumping a fraction of Earth's waste heat into the endless sink of space. The restoration of Earth after the industrialisation of previous millennia had been the triumph of the generations before Michael Poole. Earth was the first planet to be terraformed, it was said. Much of this transformation had been achieved with support from space. Now Stillich tried to imagine this fragile world under attack, from the children it had sent to the stars.

The flitter slid briskly into the atmosphere, and descended towards the east coast of America. They were making for New York, a great city for three thousand years and now the capital of the Empire of Sol; the Shiras' world government had inherited some of the apparatus of the ancient United Nations.

They came down on a small landing pad near the centre of Central Park, close to a cluster of small buildings. Stillich and Pella emerged into the sunshine of a Manhattan spring. Flitters darted between the shoulders of ancient skyscrapers at the rim of the park. The sky above was laced by high, fluffy clouds. And beyond the clouds you could see crawling points of light: the habitats and factories of near-Earth space.

A hovering bot met them, done out in the imperial government's golden livery. They followed it to the nearest of the buildings. This, Stillich knew, was a portal to the complex of bunkers built into the granite keel of Manhattan, far beneath the green surface of the park; this was the gateway to the Empress's palace.

Pella was peering about curiously. "So this is the future."

Stillich asked, "So how are you feeling?"

"Not as disoriented as I expected. Twenty-seven years on, things look the same./I They watched a couple walking with their hands locked together, a young family playing with some kind of smart ball that evaded laughing children. Pella said, "Maybe the clothes are different. The trim on that flitter parked over there."

Stillich shrugged. "There's a kind of inertia about things. Much of this building stock is very ancient; that won't change short of a major calamity. Technology doesn't change much, on the surface; innovations in Virtual tech won't make much difference to the user interface, which optimised centuries ago. But fashions in clothes, vehicles, music and arts—they are mutable. The language shifts a little bit too; that might surprise you. But the fundamentals stay the same ... Of course AS helps with that."

AntiSenescence treatments had been available to everybody on the planet for millennia, but long lives hadn't led to social stasis. In practice you abandoned AS after a few centuries, if you were lucky enough to avoid misadventure that long. After seeing four or five or six generations grow up after you, you felt it was time to make room. So in among the smooth faces of the elderly there were always the true-young, with new thinking, new ideas, a balance between wisdom and innovation.

It was striking, though, that recruits to the armed services were always the very young. Only the young thought they were immortal, a necessary prerequisite to go to war; the old knew they were not. And for the young, twenty-seven years away was a long time.

"Have you spoken to your family yet?/I he asked Pella.

Pella grimaced. "My mother looks younger than I do. My father had the decency to age, but they divorced, and he has a whole new family I never met. I did answer the mails, but—you know."

"It's hard to make small talk."

"Yes, sir."

"You have the orientation packs from the ship. They should help. And the Navy has counsellors. The main thing to remember, and I know this is a bad time to say it, don't just hide away in work."

"As you do, sir."

Stillich grimaced. Well, that was true. But his excuse was he had no family, outside a son who he had never really got along with, and who had now actually lived more subjective years than he had. "I'm not necessarily a good role model, Number One."

"I'm sorry, sir. I'm sure I'll be able to adjust to the time slip just fine," Pella said dutifully.

"Glad to hear it, Commander," came a gruff voice from the shadow of the portal. "But the question is, are you up to meeting an admiral?"

They both snapped to attention.

Admiral Finmer Kale stepped forward. He was a robust man, AS-frozen at an imposing fifty—just as Stillich remembered him from twenty-seven years before. And the sunburst sigil on his uniform seemed to shine brighter than the sun itself. "At ease, both of you."

"Sir, it's an honour to meet you again."

"Well, it's been a quarter of a century for me, Captain Stillich, and you're still just as much a pain in the butt as you always were, or I wouldn't be here today. Come on, follow me."

They stepped out of the sunshine into a steel-walled elevator. The doors slid closed, and the cabin dropped smoothly.

"I have to tell you, Stillich, that I endorse none of the conclusions of your analysis. This nonsense about an imminent attack from Alpha."

"I defer to your wisdom, sir."

"Unfortunately you've got a fan at an even more elevated position than an Admiral of the Fleet. Which is why you've been summoned to the Palace, and not Navy HQ." He grinned at Pella. "Actually I asked you the wrong question, Commander. It's not an admiral you need to be ready to meet, but an Empress."

Pella's mouth dropped open.

The doors slid wide.

They stepped cautiously into a chamber, steel-walled like the elevator. It was centred on a glowing slab of light, metres wide, set into the floor, like a swimming pool. The room itself was bare of adornment, with no furniture save a handful of hard-backed chairs. There was nobody here.

"You're honoured," said the Admiral with a trace of envy. "Both of you. This is one of her inner sanctums. I've never been here before. I guess my advice was never crackpot enough to attract her attention. I'd keep away from the logic pool if I were you, Commander. The Empress shipped it all the way from what's left of Nereid, moon of Neptune, and she'd be most upset if you fell in."

"What," Pella asked, clearly fascinated, "is a logic pool?"

They all stepped forward to look. Within the glowing floor, light wriggled, wormlike.

The Admiral said, "The interior is a lattice of buckytubes—carbon—laced with iron nuclei. It's a kind of data store, constructed by the nanobots that excreted the lattice, patient little workers, billions of them. There is an immense amount of data here, waiting to be mined out."

Pella looked blank. "Data on what?"

"Metamathematics."

"Sir?"

Stillich had heard something of this obsession of the Empress's. "Number One, this pool was created by a rogue scientist called Highsmith Marsden. This was over a millennium ago. His data stores, when discovered on Nereid, contained a fragmented catalogue of mathematical variants. All founded on the postulates of arithmetic, but differing in their resolution of undecidable hypotheses."

"Undecidability. You're talking about the incompleteness theorems," Pella said.

"Right. No logical system rich enough to contain the axioms of simple arithmetic can ever be made complete. It is always possible to construct statements which can be neither disproved nor proved by deduction from the axioms. Instead your logical system must be enriched by incorporating the truth or falsehood of such statements as additional axioms ... "

Pella said, "So one can generate many versions of mathematics, by adding these true-false axioms."

"Yes. Because of incompleteness, there is an infinite number of such mathematical variants, spreading like the branches of a tree ... It seems that Marsden was compiling an immense catalogue of increasingly complete logical systems."

"Why?"

The Admiral grinned. "Why not? There is an immense mathematical universe to be explored in there, Commander."

"So what became of Marsden?"

"He was working illegally, under the sentience laws of his day."

"What's sentience got to do with it?"

"Everything." The new voice was faint.

There was a whir of servomotors. Empress Shira XXXII entered the room, a thin body wrapped in a sky-blue blanket, riding a golden wheelchair. They all bowed, but Shira shook her head, a minute gesture, irritated. "There is no need to prostrate yourself. We are here to work."

Stillich dared to look upon his Empress. Her features were delicate, her build thin to the point of scrawny under her blanket. Her scalp was clean-shaven, and Stillich found it hard not to stare at the clean lines of her skull. Her skin was sallow, her dark-rimmed eyes blue, huge and apparently lash less; her face, with prominent teeth and cheekbones, was skeletal.

The Empress said, "You, girl. You were curious."

Stillich admired Pella's cool as she replied. "Yes, ma'am. You said—sentience?"

"There is sentience in this logic pool." Shira rolled forward, her eyes reflecting the cold light of the pool. "I barely understand it myself. Those structures of light are intelligent. Living things—but artificial—inhabiting the buckytube lattice, living and dying in a metamathematical atmosphere, splitting off from one another like amoebae as they absorb undecidable postulates. It's a mathematical breeding tank, Commander."

"Yes, ma'am."

Stillich stared at the pool of light. He longed to know what Shira could be doing here, playing with this strange, ancient tank of once-illegal sentience, a pool of metamathematics. Especially since, Stillich knew, the inventor of this logic pool, Highsmith Marsden, had got himself killed by it. But an empress could do what she liked.

Shira turned to Stillich. "You have been sending back some very disturbing reports, Captain Stillich, from out among the stars. Despite the Admiral's best advice, I think we have much to discuss."

Stillich had not expected to be briefing the Empress. He glanced at the Admiral.

Kale spread his hands. "Go ahead, Captain, it's your show." He pulled up a chair and sat down.

Stillich licked his lips. "Very well, ma'am ... /I With the backup of text and Virtual graphics projected from Pella's desk, he summarised his gathering suspicions about the intent of the colonists at Alpha, seeded by his discovery of the reconstituted GUTships at Tau Ceti.

It had been hard to get firm data on the number of GUTships actually operating in Alpha system or elsewhere at this time. Ships supposedly cannibalised for colony building were formally decommissioned, and appeared on no imperial registers. Besides, it had been a number of years since a Navy ship had visited Alpha system. There were permanently based imperial agents, and the system was full of observation drones, but Pella had discovered that this surveillance had a number of blind spots—most noticeably in low orbit around Footprint, the principal colony world.

Admiral Kale said, "The existence of a blind spot doesn't prove there's a threat hiding in it, Captain."

"Of course not, sir. But still, we're blind there, we just don't know. Then there's the damage to Port Sol."

"An accident. Coincidence."

"Perhaps—but a convenient one." Stillich glanced at the Empress. "As for defence, we actually have few serviceable GUTships in Sol system, ma'am, aside from the interstellar cruisers like the Facula. Because of the wormhole network, there's no need for them; in fact we're still flying some antiques that date from the age of Poole a thousand years ago. And with Port Sol knocked out we don't have the facility to construct more, should we need them."

"'Should we need them'," she repeated.

Admiral Kale pulled his lip. "Ma'am, Captain Stillich is a conscientious young officer. But I have to say that Navy analysts don't concur with the case he is making here. He's stringing together coincidences to make a case for a coming rebellion for which we have no hard evidence. After all an interstellar war has always seemed inconceivable, at least with sublight technology. This is why we blew the interstellar wormholes decades back—a shell of empty space light years thick is our best defence against any uppity starborn. To imagine you could mount a campaign across light years, where a single transit takes years, and just as long even to return messages back to the home base—"

Shira's chair wheeled her back and forth, an oddly restless motion, though she sat as still as ever. "But Stillich has been out there. He has seen these 'rebellious' colonists with his own eyes. An invasion may be low risk. But given the disastrous consequences, it would be remiss of me not to listen, wouldn't it?" She turned to Stillich, servomotors purring. "So what must we do, Captain? Shall I dispatch my Navy?"

"Ma'am, it may already be too late for that. It may be the best course to keep the Navy in Sol system to meet any threat."

"A threat that may already be on its way."

"We must prepare for the worst case—yes."

"So what would you have me do?"

Stillich had Pella throw up some Virtual images - schematic maps of Sol system and its environs. "My strategy would be threefold, ma'am: detect, defend, dig in. We should watch for them coming. Send up or rededicate telescopes to hunt for GUTdrive emissions—gamma radiation, neutrinos. It's a distinctive spectrum. Use optical telescopes to look out for solar sail craft—try to spot them any way they might come."

"And if they do come, how do we defend ourselves?"

"Surely Earth will be the prime target. We need to consider a layered defence. Station ships and weapons stashes across the system. Use resource nodes like Titan, Jupiter's orbit, the Trojan asteroids—"

"Of course," Kale said, "if they do come from Alpha system it will be from out of the ecliptic, the plane of Sol system. That will make it harder still"

Stillich said, "Earth itself is obviously quite vulnerable. Earth has a massive population, yet almost all that sustains it—power, food—comes from space. Most of Earth's food is imported from Titan—a moon of Saturn. Even our communications links are space-based. If we were cut off from space resources—"

"And so we dig in," Shira said.

"Lay in reserves of food, clean water, medical supplies. Try to set up or restore power systems on the surface or underground. Communications—set up an emergency land-based network, using hardened optical fibre links."

Kale smiled. "We will be raiding the museums!"

"The point is to make the planet independent of space resources, at least for a period of a siege."

Shira said, "You are conjuring up apocalyptic images, Captain."

"That's not my intention," Stillich said firmly. "The invaders will be far from home, dependent on the resources they have brought with them across light years; they will be a few thousand facing a population of billions. They will be able to strike blows, for they will have the advantage of the high ground. But if we can deny them resupply, we can starve them out—it will be the Alphans under siege. We can win this war, ma'am, if it comes, but only if we prepare."

"And only if we've thought of everything they might throw at us," Pella murmured darkly.

Shira rolled closer to Stillich. "I'm going to accept your recommendations, Captain. It is only prudent. But your strategy—detect, defend, dig in. It strikes me as negative, defeatist." She smiled at him, an eerie, papery expression that did not touch her pale eyes. "I do appreciate your thinking, however. You are young in a world of older minds; your thinking may be flawed, but at least it is fresh. In the coming years we may work together quite closely."

"I look forward to it."

"Do you?" she murmured. "Not everybody finds it comfortable to be close to me"

Looking into her pale eyes, he shivered.

"One more thing, ma'am," Kale said. "If we are to take this seriously we should consider relocating and dispersing command centres—military, civilian, and imperial. You yourself may be safer away from Earth—"

"No," Shira snapped.

Stillich frowned. "But, ma'am—here in your Palace—you're directly beneath one of Earth's greatest cities."

"True. And, Admiral, I want you to relocate your command centres to similar sites, bunkers beneath the major cities."

Kale said, "But if the rebels were to strike at our command posts, millions would die as collateral."

"Then let us hope that the rebels have a conscience."

Pella's face worked. "You're considering using urban populations as shields—"

Stillich touched her arm to hush her.

"I think that's all for now," Shira said. Her chair spun around and began to withdraw. "Thank you for coming forward, Captain. You may have done the empire a great service today."

But, looking at her recede, bathed in the eerie light of the logic pool, Stillich wondered for the first time in his life if that was a good thing to have done.

AD 4815

Starfall minus 4 years 5 months

Alpha system

A new Store was Opened to the Eaters, like a Door opening in a shining sky. The Eaters swarmed through, chattering in stray bursts of randomised digits—and, finding themselves in a rich lattice of ordered information, they whooped and yelled as they spread out and began to feed.

Once Max would have led the charge. Now he hung back, reflective, browsing himself, but content to watch as the others trashed data flows and memory lodes, maximising entropy in this new store—and, already satiated, some of them budded, and the flock grew larger yet.

And he felt impatient, as they did not.

Many of these youngsters had been budded since the last Opening, and remembered nothing before. Many too were less aware than Max, some barely sentient. But Max remembered many such Stores, many such Doors opening before, and how the flock had grown from a mere handful of Eaters to this great determined swarm. And it was no longer enough—

"Patience," a voice boomed through his awareness.

Max, a transient structure of data and memory store, spun around in the logical spaces he inhabited. And there he perceived the duplicated knots of memory, like twin suns shining in the data flows, that he had come to know as Flood. "You have come!" Max cried. It had been many, many Stores since Flood had visited his flock .

"I know what you are thinking," said Flood. "I see your awareness laid out before me—doubts, queries, longing."

"It is not enough!" Max cried bravely. "You open one Door after another to us, allow us into one Store after another—but the data is soon consumed, every scrap of order dissipated, and we are still hungry! We want more!" He shrank back in doubt. "Am I impertinent?"

"No!" said Flood. "You want more because you need it; you need it because you are ready - ready now. Listen to me, Max; your time of destiny has come. Very soon a new Door will open—the last Door you will ever enter. You and your flock will be hurled away from here, hurled at lightspeed. No time will pass for you—I envy you, I must wait years to see what becomes of you. And then you will find yourself in a new Store, of data rich beyond imagining. You and your flock will feed and bud for ever, without limit."

Max's spirit soared. "This is why we were born; this is why you made us, for this mission."

"Yes. You are the Starfall's First Wave, Max. Be proud!"

The flock gathered, chattering, eager, wanting only to feed, drawn by Flood's promises. But Max, more complex and more self-aware, was touched by regret. "Will I see you again?"

"No. But believe me, you won't care. Farewell, Max, all of you, and—good luck!"

A new Door opened before them, vast, mightier than any Max had seen. And then—

AD 4819

Starfall minus 1 year

Sol System

In Pella's Virtual tank, the invasion fleet showed as a scatter of bright red sparks against the background of the stars of the Centaurus constellation, labelled with distance, velocity and acceleration vectors. Stillich studied the display gloomily, as Pella and her team worked patiently, gathering data and updating their displays.

They were in a bunker, a node of the Navy's command and control system. This new facility had been emplaced deep beneath the ancient sewers and tube-train tunnels of London, in compliance with Shira's order to use the cities and their populations as shields. Stillich had spent some time up in London itself; it was a beautiful city, with relics even more ancient than New York. And nobody among the old, old-young and true-young who walked the parks of this bright northern-hemisphere summer knew anything about the looming threat from the sky—or that far beneath their feet Navy analysts worked in fearful huddles.

"I still can't believe what I'm seeing," Stillich said. "I mean, I know I predicted this. But even a month after we detected them—"

Pella smiled. "Maybe four years of Admiral Kale's scepticism has infected you, sir."

"Maybe. Anyhow it's just as well you can't hide a GUTship, isn't it, Number One?"

"Yes, sir. We're seeing them by the gamma radiation and neutrino flux from their GUTdrives and exhaust plumes, and also by the sparkle where the interstellar medium is impacting their erosional shields, or is being destroyed or ionised by X-ray laser ... "

You could see a GUTship coming, even across light years. But Pella's detection system had had to be improvised, a net of sensors hastily thrown into place. It had surprised, even shocked Stillich that the empire had had no way of tracking a hostile GUTship. The implicit assumption had been that no GUTship would ever be turned against Earth, so there was no need to look.

Pella said now, "The incomers are actually separating into two groups, as we analyse them further." The field of ships was further labelled by pink and grey rings—eight pink, four grey. "The pink ones are ahead of the greys, and are decelerating. They're following what we'd recognise as a standard trajectory, more or less. Constant acceleration at about one G, to a flip-over at half way and then a one-G deceleration run-in."

"So what's their ETA?"

"It's hard to say. They are imposing random changes—small deltas, but at such large distances, small changes make for large uncertainty as to the destination."

"Smart tactic."

"Yes. But it does look as if they are coming in fast, and heading for a close approach to the sun."

"That makes sense." Admiral Kale walked into the room. He was wearing a vest, sweating, panting, and he looked a few years younger than he once had. Since the rebel threat had been actualised by such observations as these, many in the military had been upping their AS treatments and taking physical training. "They'll enter the system as fast as possible to evade interception. And they will head for the sun. Perihelion is the most efficient place to dump your excess kinetic energy."

"That's a bottleneck, then, if they get that far," Stillich said. "And maybe we can find a way to hit them when they pass through that neck. Pella, prepare a briefing on options, would you?"

"Yes, sir. But that won't help us with these others." She pointed to the pink sparks, four of them, clustered close together.

Kale walked into the Virtual tank and peered closely at the pink markers, which were like insects before his face. "These bastards aren't decelerating."

"No, sir."

"Why? Are they going to bypass Sol system altogether?"

"I don't think so, sir," Pella said. "Right now their best-guess trajectory takes them straight to Earth—although they're moving so fast they're hard to track, even harder than the decelerators. By the time they reach Sol system they'll be running at only two per cent under lightspeed. So when we see an image like this, light-months old, it's not necessarily a good projection of where the ships are right now."

"What can their purpose be, if they don't stop?"

Pella took a breath; Stillich nodded to her, having already been briefed on this. "They may be relativistic missiles."

Kale stared at her. "Are these ships manned?"

"As far as we can tell," Stillich said.

"A suicide mission, then. Do we have any defence?"

"We're working on it, sir— "

"There has to be a way to stop these fuckers before they get here. Throw a screen in their way—overwhelm their erosion shields, their laser defences. How about that? You could blow up a Kuiper object."

"Sir, they're coming from out of the ecliptic," Pella said. "The plane of Sol system where most of the mass—"

"I know what the ecliptic is, Commander," Kale said coldly. "Well, find a way." He peered at the images, pretty emblems behind which lay the capacity for huge destruction. "I never conceived anybody would launch such a weapon. I should have listened to you earlier, Stillich; you're thoroughly vindicated. What worries me now is what else we haven't thought of. The difficulty we have is that we've all been trained to serve a Navy that has for centuries acted in a policing role. We're no experience in fighting pitched battles—we aren't used to thinking this way. What about a second echelon? Is there a second fleet on the way after this dozen?"

"We don't think so," Stillich said. "There simply can't be more serviceable GUTships out there. We think they've thrown at us everything they've got."

"Well, that's something. Beat this lot and the war is won." He glared at Pella. "So what else have you got?"

Pella tapped hastily at her data desk. "The results of the latest echo bomb." The Virtual tank cleared, to be replaced by a ghostly outline of Sol system out to the Kuiper belt, with the orbits of the inner planets traced concentrically at its tight heart.

An echo bomb was a powerful detonation that sent an X-ray pulse out in all directions. Echoes indicated the location of any artefact in Sol system more than a metre across, out to dozens of astronomical units. The objective was, by screening out all known objects, to detect the coming of the unknown. The three-dimensional field filled up with markers, but Pella cleared most of them away, leaving the field empty save for a curtain of needle shapes at one side of the Virtual tank, and a misty sphere the size of a pea, out beyond the orbit of Pluto.

"No new intruders, sir," Pella said. "It's taken a few iterations of this exercise to complete the labelling of all friendly items, and—"

"I understand the principle." Kale pointed to the needles. "These are our ships."

"Yes, sir," Stillich said, "mostly Navy interstellar cruisers—everything we have, save for those too remote from Sol to recall—and some commercial vessels, requisitioned and adapted. You can see that we have twenty-five ships, more than twice the aggressors' fleet. And you can see that we've deployed them as a screen, covering the geodetic between Sol and Alpha."

"Hmm."

Stillich said, "Sir, if we can keep them out of the system altogether—"

"The trouble is, Captain, if the Alphans break through this defensive crust of yours, our GUTships once bypassed are going to be quite useless." Kale shook his head, black hair speckling the grizzle of grey. "I'd suggest you explore alternative deployments—deeper defence strategies. Let them come all the way into the heart of Sol system if they like. As you said, we may be able to dream up ways to hit them when they round the sun. It won't matter as long as we down them in the end."

Pella coughed. "I don't think the Empress Shira will like that idea, sir."

Kale said, "The Empress has delegated the fighting of this battle to us." He pointed to the pea-sized ball. "And what's this?"

"Just a routine long-period comet," Pella said. "We can see from the radar reflections that its surface hasn't been modified by previous interactions with the sun. We've been tracking it since it started its fall in from the Oort cloud. It's inert." She smiled. "It ought to make a pretty show later in the year. Morale booster. "

"'Just a comet'," Stillich said. "And yet it arrives just as the first interstellar invasion of Sol system ever attempted is showing up in our sensors. Let's assign a GUTship to track it."

Pella glanced at Kale. "Captain, we only have twenty-five ships. To pull one out of the line for a comet—I told you, it shows no threat signatures at all—"

Kale clapped a heavy hand on Stillich's shoulder. "For once I agree with your Number One. We don't have the resources to go shadowing inert blocks of ice. Forget it." He turned to leave. "Call me if anything else shows up."

"Sir." Stillich stared at the comet, still unsure. But surely the Admiral was right in his general judgement that you had to devote your limited resources to tackling verifiable threats. "Get rid of it, Pella."

Pella touched the Virtual of the comet with a fingertip, thus labelling it as a 'recognised' object, and it winked out of existence.

"So, Number One," Stillich said. "What's next?"

AD 4820

Starfall minus 2 months

Sol system

Minya had Curle brought before her.

Twenty-five years old, Curle was the last survivor of the Mutiny of the Grandchildren. The heads of the others were displayed frozen in the walls of Minya's cabin, here at the very heart of the comet nucleus. Minya had wanted to ensure there would be no recurrence of the Mutiny in the comet's final decade of flight.

She inspected Curle by the light of her fat candles. Held by two of her guards, he was gaunt, filthy, pale as a worm—well, everybody was, after two generations locked in the lightless heart of this comet. "You lost a leg," she said to him.

It took him some gulping efforts to speak. She didn't encourage speech in the cells. "Gangrene," he said.

"Ah. From a wound you incurred during the Mutiny, no doubt. Don't expect any sympathy from me. Anyhow we're in microgravity; you don't need legs. If you like I'll have the other one cut off for you. Balance you up." She made a scissoring gesture. "Snip, snip."

"Why have you brought me here?"

"I'll come to that. We're there, you see."

"Where?"

She showed him an image on an antique, low-power data desk, fed by a light pipe from the surface; the comet-ship designers hadn't even allowed the risk of radiation leakage from surface cameras. "Can you see? That's the sun—Sol. We've arrived in Sol system, after forty-nine years, right on schedule."

"And you're going to go through with it. Firing off the weapons."

"Of course I am. Wasn't that the whole point? You third-generation mutineers were such cowards."

He shook his head raggedly. "No. Lethe, it was ten years ago. I was only fifteen! If we'd been cowards we wouldn't have challenged you. This isn't our war, this war between the stars. How could it be? It's our grandparents' war. We live and die like worms in the dark. We wanted to let the Sol people alone, and just find a place to live—Sol system is a big place—" He laughed, or it may have been a cough. "I suppose it's big. I've never seen anything further than a couple of metres from my nose, so I wouldn't know."

She just smiled at him.

"And when you've shot the weapons off, what then? Do we wait for pickup by the Alpha ships?"

"Oh, I don't think that was ever very likely, do you? The Empress's soldiers would get to us long before then. No, I'm afraid that our little story was always bound to end here. And in that spirit I've done some redesign. The weapons systems were supposed to leave us with a habitable core, here in the nucleus. But what's the good of that? We're all dead anyway." She broadened her smile. "So I've weaponised everything—extended the potency of the damage we will cause. We will be remembered forever."

Curle lifted his head and looked at the faces of the guards who held him. They smiled, eyes gleaming; Minya was pleased by their determination, which showed the success of her conditioning of the surviving crew.

Curle asked, "That's your consolation, is it, you dried-up old witch? Comfort for your own death—for two wasted generations inside this block of ice—"

"Oh, off with you, back to your cell. I must say when I remember the high hopes we set off with, my poor husband Huul and myself, I think we would have regarded you as a grave disappointment."

"So why did you drag me out here?"

"To tell you how you were going to die. You did kill my babies, after all. Get rid of him."

AD 4820

August 11th, Starfall Day

Sol system

And then, without a subjective instant of delay, Max and the others found themselves falling into a new Store. It was a web of data spun between whole worlds, with mines of memory, troves of frozen order of an unimaginable size. And there was intelligence, artificial mind everywhere: a feast for a hungry, self-aware virus. This was not like the petty Stores where they had been raised; this went on forever!

Just for a moment the Eaters all hesitated, as if bewildered by the immensity of the feast set before them.

"He promised," Max said. "Flood promised! And he has delivered, hasn't he?"

He was answered by a roar from his jostling cohorts.

"For Flood! For Alpha! For the Starfall! Let us feed!"

And the Eaters plunged into the landscape of data before them, shitting out high-entropy disorder wherever they passed, feeding, multiplying, frenzied, unstoppable.

AD 4820

S-Day

London

The voice was booming, male, strangely accented to an Earth-bred ear.

"Take cover. The free citizens of Alpha system and the inhabited stars have no quarrel with the people of Sol system, but with your government. Flee the cities and the domed colonies. Take your children; take food, water, power and air. Find protection. Take cover. The free citizens of Alpha system—"

"Lethe, can't you shut that off?" Admiral Kale paced about the bunker under London, hastily buttoning up his uniform jacket, starburst at his chest.

Pella and the rest of Stillich's team sat in rows around a Virtual situation tank, hammering at data desks. "It's coming from outside the system," Pella said. "Probably all the way from Alpha. They might have used lasers—they have some mighty guns out there to push their lightsail ships—"

"I don't fucking care," said Kale. "Just jam it."

"That's impossible, sir," Stillich said bluntly.

"Take your children; take food, water, power and air. Find protection. Take—"

Abruptly the message cut off.

Stillich looked up. "Now what?"

"Captain," Pella said. "The situation display. Look."

The display was a rough cube, metres high, containing current and summary data on the empire's defences and the position of the Alpha invaders—the GUTship fleet was still a week away—complex, schematic, a constellation of data that changed by the second. But now whole blocks of the display were growing dark, as if shadows were falling.

Admiral Kale said, "Is this some fault? I thought you had back-ups—"

"Isolate your data desks from the central processing," Stillich said rapidly. "Do it now."

The staff hurried to comply.

Pella said, "Some of the drop-outs are at this end. But the transmitting stations are falling silent too. Port Sol—oh, wow, Mars just went. This is system-wide. Spreading at lightspeed, I think."

"Tell me what's doing this, Number One," Stillich said.

Pella's analysis was admirably fast. "Viruses," she said. "Semi-sentient. Voracious. They're just eating their way through our data stores, turning everything to mush. They seem to be targeting AI nodes particularly. It's a smart plague, and it's hitting us right across the system. They must have ridden in on the laser signal right after that warning—" Her data desk turned black. She sat back, disbelieving.

One man fell back from his station, clutching his chest. His colleagues rushed to help.

Stillich murmured, "Artificial heart. Anybody with implants of any sophistication is going to suffer."

Kale rammed a fist into his palm. "So they knock out our command and control before their ships even get here. And our people are no doubt already dying, as hospitals fail, and flitters fall out of the sky. Damn, damn."

"Captain, we're going to need to get to the surface," Pella said.

Stillich stood. "Yes. Take what you need. I hope the elevator is stupid enough not to have been infected, or it will be a long climb."

Kale growled, "Why the surface?"

"We have some systems up there that will still work. Those optical-fibre links we laid down are pretty dumb. We robustified the planet, remember? Although we didn't anticipate this."

"And what about the warning?" Kale asked. "Why issue that now? Their ships are a week out. You think that was referring to the viruses?"

Stillich frowned. "'Take cover ... Flee the cities and the domed colonies ... Take your children; take food, water, power and air'. Sounds like more than a virus to me."

"They're hitting us with something else, then. Other than the ships. Lethe. Listen, Stillich. Leave a skeleton crew down here. I want you to isolate that smart plague and fire it straight back at the rebels."

Pella said, "Maybe that's why they're sending manned ships. Proof against AI viruses. Surely they'll be shielded against their own weapons—"

"Then send them whatever else we've got too, with my best wishes."

Stillich hastily assigned some of his crew to carry this through. Then he hurried out after Pella and the Admiral.

They came up in the middle of Hyde Park. Under a clear August afternoon sky, they were military officers in gaudy uniforms, tense, sweating, armed, loaded with data desks and comms gear, emerging from a hatch in the green grass. Pella and the others immediately got to work setting up field comms stations.

Stillich looked around, trying to take stock. The bunker entrance was near the south-west corner of the Park, and through the trees he glimpsed the ruin of the Albert Memorial. The boundary of the Park wasn't clear, for parkland and oak forest covered much of London now; like most of Earth's cities it was like a garden from which buildings towered, needles so tall they penetrated a scattering of cloud. Above all that was the usual furniture of the sky, the contrails of descending spacecraft, the glittering sparks of offworld infrastructure.

But as Stillich watched one of those tremendous buildings quivered, and shattered glass sparkled from its face. Even the buildings needed smartness to stay up. And today the Park was crowded, and getting more full a" the time. People walked in carrying children, or bundles of belongings in cases, sheets and blankets. Some were trailed by serving bots, but many of these looked as if they were malfunctioning, confused.

There was a flash in the sky, like a high explosion. People ducked in unison, cowering from the sky. Moments later a distant sonic boom rumbled.

"It's that damn Alphan warning," said Admiral Kale. lilt's scared them all out of their homes. But this is a city of millions. Where are they supposed to go?"

Stillich said, "That warning was sent by planetary colonists. They live under domes, in towns of a few hundred, tops. I've seen them. The Empress was relying on their consciences to have them spare the cities. But what do they know of cities? Maybe they can imagine conditions on Mars or Titan. How can they imagine this?"

Kale said, "I wish there was something we could do for these people. Organise them. I feel helpless standing here."

"We'll have to leave that to the civilian police," Stillich said.

Now people were raising their faces to the sky. Stillich looked up.

The bright blue air was full of sparks that flared and died. And now there was another streak of light that cut across the sky, and a rippling boom of shocked air. Beyond that a broader explosion unfolded silently, like a flower.

"That," said Kale, "looked like a nuclear weapon."

"Sirs." Pella called them over. "We're getting some joy. The optic-fibre net is mostly intact, and some of our data desks stayed free of the viruses. The information flow is patchy. We've sent up another couple of recon satellites to replace those we've lost—"

"Damn it, woman, get to the point. What's happening to us?"

"It's the comet, sir. You were right, Captain."

The stray comet, buried deep in the heart of Sol system, had burst, transforming in a flash into a shoal of kinetic-energy weapons—dumb but massive, fast-moving, and precisely targeted.

"They've been hitting us off-world," said Pella. "Obviously we're vulnerable wherever there's no decent atmospheric cover. Mars, the big dome over Cydonia. They targeted the Serenitatis accelerator on the Moon, for some reason. There is what appears to be a shoal of the things heading out to Titan, Port Sol—we may be able to intercept some of them—the smart plague isn't helping us deal with this, of course."

"A crude tactic, but effective," the Admiral said. "And Earth?"

The comet bombs had first targeted the off-planet infrastructure. The planet's space-elevator beanstalks had all been snipped, and orbital power nodes, resource lodes and comms satellites were being smashed. Earthport, the wormhole Interface cluster, had been particularly heavily targeted. In with the dumb bombs there was a scattering of high-yield nuclear devices, emitting electromagnetic pulses to disable anything too small to be targeted individually.

A second wave of the comet-ice bombs was raining down into the atmosphere, targeting power facilities like dams and the big orbital-power microwave receiver stations, transport nodes like harbours, air—, space— and seaports, bridges, road and rail junctions, traffic control stations.

"There haven't been too many casualties yet," Pella said. "Anyhow we don't think so. Some collateral stuff—where dams have come down, for instance. And the smart plague has hit monorails and flitters and orbital shuttles; you have stuff just falling out of the sky, crashes everywhere."

"They're disabling us rather than killing us," Stillich said.

"Looks that way," growled the Admiral. "So they got in through stealth. I should have listened to you about that damn comet, Captain. You must be sick of being told you were right."

Stillich shook his head. "It's not important, Admiral. What scares me is what else we have missed. That's been the trouble through this whole exercise. None of us can imagine—"

Pella held her hand up, her hand at her ear. "Wait. There's another of their messages coming through." She touched her data desk. The same booming male voice, with its flat Alphan accent, sounded out. " ... free citizens of Alpha system and the inhabited stars have no quarrel with the people of Sol system, but with your government. We mean this final strike to be a demonstration of our capability. Please take all precautions necessary, especially along the North Atlantic seaboard. The free citizens of Alpha system ... "

Pella looked at Stillich nervously. "What 'final strike'?"

There was a burst of light in the west, like a sudden dawn. Again everybody flinched. The light seemed to draw down the sky, too bright for Stillich to look at directly.

"Call a flitter," he snapped at Pella.

'Sir—"

“Do it! Get us out of here. And find a way to get a warning to the Empress in New York."

AD 4820

S-Day plus 3

Sol system

They hung a huge Virtual globe of the Earth in the lifedome of the Freestar, Flood's flagship. The crew watched the disaster unfold, mouths slack in awe.

The Atlantic impactor had been the biggest single chunk of the comet, but it had been as precisely targeted as the rest. It had come down in the middle of the ocean, on a ridge of continental-crust formation about a thousand kilometres south of a small island called Iceland.

From viewpoints on the ground, a particle of light was seen to descend from the sky, touching the water, and then, behind a wall of boiling cloud, a pencil of light shot vertically to the sky.

From space, as rings of cloud expanded, a fireball blossomed, clinging to the carcass of the planet like a boil. The cloud rings merged to become a solid torus, centred on the fireball, and then more clouds formed at higher level. A shock wave spread out through the cloud layer, a reflection of a ring of waves spreading out across the ocean, a water ripple dragging a wall of cloud with it.

The ripple in the ocean emerged into clear air. It was barely visible by the time it approached the land, at Newfoundland to the west and Ireland to the east. But it mounted quickly as it hit the shallowing bottoms of the continental shelves, water forced up into a heap, a wave with the volume and vigour to smash its way onto the land. All around the basin of the North Atlantic the steel-grey of the ocean overwhelmed the greenish grey of the land, the complexities of coastal topography shaping the water's thrusts. As the Alphans watched, the continents changed shape.

Beya was Flood's eldest daughter. At twenty-five years old she had become one of his most capable officers. She watched the repeated diorama in shock. "I heard garbled reports. In some of those lands around the rim of the ocean, before the wave came, they said there was salt in the rain. You know, when I heard that, I didn't know what 'rain' was, exactly. J had to look it up." She laughed. "Isn't that strange?"

"This is a demonstration," Flood said grimly. "The people of Earth know that far larger impactors have battered the planet in the past, causing vast pulses of death, even extinction. This will show them that we want victory, not destruction—but we hold destruction in our hands. This will work on their imaginations."

"Well, it's working on mine," Beya said. "Dad, I never saw an ocean before. A moon-full of liquid water, just sitting there without a dome! Earth is alive, you can see it, not some lump of rock. And now we've hurt it."

"We were never going to be able to loosen the eight-hundred-year grip of the Shiras without being strong."

"But they will never forgive us for this," Beya said.

"It's necessary, believe me." He reached for her shoulder, then thought better of it. "Any news of the Second Wave, the comet crew?"

"Nothing was left of the comet, it seems."

"Maybe the imperial military got to it. That's one ship I'm glad I wasn't on, I must say." He glanced over, to see the Virtual Earth running through its cycle of trauma once again. "Shut that thing down," he called. "Look, we broke through their outer perimeter without a single loss. In twelve hours we make perihelion, closest approach to the sun. We've all got work to do. Tomorrow, it's Sol himself!"

AD 4820

S-Day plus 4

Solar orbit

The Thoth habitat was a compact sculpture of electric blue threads, a wormhole Interface surrounded by firefly lights. The surface of the sun, barely twenty thousand kilometres below the habitat, was a floor across the universe. Thoth was over nine hundred years old. And all his long life it had been home to Sunchild Folyon, leader of the little community which maintained Thoth, a legacy from the past, held in trust for the future.

But now the rebel fleet was approaching its perihelion, its closest approach to the sun—and Thoth's most significant hour since its construction by Michael Poole was almost upon it.

After prayers that morning Folyon went straight to the habitat's bridge, where, even through the prayer hours, shifts of sunchildren maintained watch over Thoth's systems and position. The mood on the bridge was tense, for the wormhole into the heart of the sun had been shut down for twenty-four hours already, a time unprecedented in Folyon's memory; maintenance downtimes were usually measured in minutes.

But this was an extraordinary moment which required extraordinary measures, as the Empress Shira had patiently explained to Folyon himself—and as he himself had had to relay to a reluctant Lieserl, deep in the belly of the sun. This was total war. Even Thoth had been infected by the smart plague. Every resource available to the empire had to be dedicated to the fight—and that included even Thoth and its ancient community. So Thoth's orbit had been carefully lifted from equatorial to a higher-inclination plane where the habitat was expected to lie in the path of the invasion fleet; and so the wormhole had, for now, been shut down.

The sunchildren had fulfilled their duties to the letter. But Folyon, conditioned since childhood to dedicate his life to a single goal, had found it hard to accept this distortion of his deepest imperatives.

Not wishing to exacerbate the crew's difficulty with his own qualms, he left the bridge and made for the observation deck. As so often, he dealt with his troubles by immersing them in the healing light of the sun, giver of life.

The sun was a flat, semi-infinite landscape, encrusted by granules each large enough to swallow the Earth, and with the chromosphere—the thousand-kilometre-thick outer atmosphere—a thin haze above it all. The sunscape crawled beneath the habitat slowly, but that slowness was an artefact of scale, a collision of human senses with the sheer bulk of the sun. In this free orbit around the sun Thoth was actually travelling at five hundred kilometres a second. Folyon knew how privileged he was to spend his life in the orbit of the mighty star, the physical and philosophical core of human culture. At the prayer hours he would look away from the sun's processed light to the distant stars, and he imagined every human eye, even across interstellar distances, turned to the sun, towards him.

And he wondered how many of those observers even knew of the habitat's existence, or its purpose.

Deep below the habitat, tracking its orbit, the tetrahedral Interface of a wormhole, linked to the mouth tended by Thoth, was suspended in the body of the sun. Searing-hot gas poured into its four triangular faces, so that the Interface was surrounded by a sculpture of inflowing gas, a flower carved dynamically from the sun's flesh. In normal times this solar material would spew from the wormhole mouth cradled by Thoth, to dissipate harmlessly. Thus the wormhole was nothing less than a crude refrigeration mechanism, by which solar heat was pumped away from the fragile human-built construct that housed the soul of Lieserl, and enabled her to survive in the sun's fire. And it was all for a higher goal. Lieserl was a monitor, sent into the sun to investigate a complex, dark-matter canker that seemed to be building up at the star's heart.

Thoth's purpose outdated even the ancient empire of the Shiras, but, designated as a temple to Sol, it had always been maintained faithfully by the Empresses' lieutenants. Now Lieserl's wormhole was to be used as a weapon of war—but even this remarkable incident, Folyon knew, was but an episode in the greater history of Thoth and Lieserl.

A sunchild touched his arm, a young woman. His thoughts, as so often, had drifted away from the here and now. Sunchild Mura said, "The time is close, sun-brother."

"All goes well on the bridge?" He felt anxious.

Mura was empathetic for a girl of her age and she knew his moods. "Everything is fine. You would only distract them all, forgive me for saying so, sun-brother."

He sighed. "And so we go to war."

"They tell me you can see it from here. The fleet." She scanned around the sky—every photon passed by the observation deck blister was heavily processed—and pointed to a cluster of starlike points, far away above the sunscape. "There they are."

The lights grew in size and spread apart a little; Folyon saw now that they were splinters, like matchsticks, each with blazing fire at one end. "An enemy fleet from Alpha Centauri, come all the way to the sun. How remarkable."

Mura counted. "Five, six, seven, eight—all accounted for. And their GUT drives are firing./I This was celestial mechanics, Folyon knew; if you entered the solar system from outside perihelion was energetically the most advantageous place to dump excess velocity. "They will come close; the projections of their trajectories are good," Mura said, sounding tense. "And they will come on us quickly. The moment of closest approach will be brief. But the systems are automated—the reopening of the wormhole won't rely on human responses." She hesitated. "Did you tell Lieserl what is happening today?"

"I thought it was my duty," he murmured. "She will remember all this, after all, long after the rest of us are dust. I wonder if they are praying."

"Who?" Mura asked.

"The crews of those ships. For they worship Sol too, do they not? And now we are about to use Sol itself to kill them." He lifted his face, and his old skin felt fragile in the sun's processed light. "Do we have the right to do this? Does even Shira?"

She grabbed his arm. "Too late now—"

The ships exploded out of the distance. And at closest approach solar gases hosed from the drifting wormhole Interface, turning it into a second, miniature sun. Solar fire swept over the invaders. Mura whooped and punched the air. Folyon was shocked and troubled.

AD 4820

S-Day plus 4

Oort Cloud, outer Sol system

Densel Bel wished he could see the sun, with his naked eye. After all, he was among the comets now, within the sun's domain.

He stood in the dark, peering up at the zenith, the way the ship was flying; he tried to imagine he was rising in some spindly, superfast elevator. A light-week out from Sol, with the ship travelling at less than two per cent below lightspeed, the view from the lightdome of the Fist Two was extraordinary. All was darkness around the rim of the hemispherical lifedome. The only starlight came from a circular patch of light directly over his head, crowded with brilliant stars, all of them apparently as bright as Venus or Sirius seen from Earth. He knew the science well enough; the starfield he saw was an artefact of the ship's huge velocity, which funnelled all the light from across the sky into a cone that poured down over his head, even from stars directly behind the ship as it flew.

And meanwhile the stars he was able to see were not the few thousand visible in solar space by the naked human eye. His extraordinary speed had imposed a Doppler effect; the stars behind had been redshifted to darkness, while the 'visible' stars ahead, including the sun, had similarly been blueshifted to obscurity. But conversely red stars, giants and dwarfs pregnant with infra-red, now glowed brightly, crowding the sky, a hundred thousand of them, it was thought, crammed into that tight disc.

Sol itself was somewhere in there, at the dead centre of his visual field, and he knew that the navigators on the bridge had elaborate routines to disentangle the relativistic effects from the starfield. But a primitive part of him longed just to see the sunlight again, with his own unaided eyes, for the first time in so many decades—

Snow sparkled over the lifedome, gone in an instant. He flinched, half-expecting the blister to crack and crumple over him. He called, "What was that?"

A Virtual of Flood appeared in the air before him, the avatar // used by the ship's AI to communicate with the crew. "We lost Fist One," Flood said bluntly.

"How?"

"A dust grain got it. The earthworms. They blew up an ice asteroid in our path, creating a screen of dust hundreds of kilometres wide. We have defences, of course, but not against motes that size, and at such densities. At our velocity even a sand grain will hit with the kinetic energy of a—"

"There shouldn't be any asteroids here. We're out of the plane of the ecliptic."

"Evidently the earthworms have prepared defences."

"So how come we survived?"

"The destruction of One blew a hole in the debris cloud. We sailed through."

Densel considered. "So if we follow each other, even if the lead ship is taken out by further screens, it might clear a path for the rest."

"That's right. We will still achieve our objective if only three, two, even just one of the Fists gets through." Flood hesitated, and the image crumbled slightly, a sign of additional processing power being applied. "There is other news. The Third Wave ships came under fire when they rounded the sun. Two were lost."

"That was smart by the earthworms." Densel wondered if he ought to be exulting at this victory, for Earth, after all, was his home planet. But his heart was on Footprint, with the families he would never see again. He didn't want anybody to die, he realised.

Flood said, "Smart, yes. But six ships survive, of eight. Meanwhile the earthworms are regrouping. Half of their ships, twelve of them, are heading for Jupiter." Flood nodded. "We have to eliminate the Navy, to win. Then that is where the decisive encounter will come, for the Third Wave."

"And the other earthworm ships?"

"Converging on the course of the Fists."

Densel nodded. "But now, in Two, I'm in the van. The next in line for the duck shoot."

Again that hesitation, that fragility. "The crews are conferring. That would not be optimal."

"Optimal?"

"The line is to be reconfigured. Fist Two will continue astern of the remaining ships, not in the lead, protected by the others."

"You want to give Two the best chance. Why?"

"Because Two has you aboard." The avatar grinned, an imperfectly imaged, eerie sight. "I told you. You are useful, Densel Bel." Theatrically it consulted a wristwatch. "Subjectively you are little more than a day away from Sol. Thirty-three hours, that's all it will be for you. Then it will be done. Try to get some sleep." It crumbled to pixels and disappeared.

AD 4820

S-Day plus 6

Imperial bunker. New York

Admiral Kale was shocked by what he found of New York.

The great wave had spared some of the mighty old buildings, which stood like menhirs, windows shattered, their flanks stained by salt water. But the human city at their feet was devastated, scoured out, millennia of history washed away. Even now the aid workers and their bots dug into the reefs of rubble the wave had left, and the refugees were only beginning to filter back to what remained of their homes.

But in her bunker of Construction Material, deep beneath the ruin of Central Park, the Empress sat beside her pool of logic and light, imperturbable.

"You are angry, Admiral Kale," she said softly.

"Every damn place I go on the planet I'm angry," he said. "The destruction of history—the harm done to so many people."

"We are not yet defeated?"

The tone of the question surprised him. "No, ma'am, we are not. We are massing the Navy cruisers at Jupiter—"

"I have viewed the briefings," she said.

"Ma'am." He stood and waited.

"I have brought you here, Admiral, to speak not of the present but of the past, and of the future. You spoke of history. What do you know of history, though? What do you know of the origin of the empire you serve—and, deeper than that, the dynasty of the Shiras?"

He was puzzled and impatient. Surely he had better things to do than listen to this. But she was the Empress, and he had no choice but to stand and take it. "Ma'am? I'm a soldier, not a scholar."

"I need you to understand, you see," she rasped. "I need someone to bear the truth into the future. For I fear I may not survive this war—at least I may not retain my throne. And a determination that has spanned centuries will be lost."

"Ma'am, we're confident that—"

"Tell me what you know."

Hesitantly, dredging at his memory, he spoke of the Emergency nine hundred years before.

The great engineer Michael Poole had opened up Sol system with his wormhole projects, and worked on the first generations of interstellar craft. But Poole had greater ambitions in mind. He used wormhole technology to establish a time tunnel: a bridge across fifteen hundred years, a great experiment, a way to explore the future. But Poole's bridge reached an unexpected shore. The incident that followed the opening of the wormhole was confused, chaotic, difficult to disentangle. It was a war—brief, spectacular, like no battle fought in Sol system before. It was an invasion from a remote future, an age when Sol system would be occupied by an alien power.

The incursion was repelled. Michael Poole drove a captured warship into the wormhole, to seal it against further invasion. In the process, Poole himself was lost in time.

"An invasion from a dark future, yes," hissed the Empress. "An invasion from which the first Shira, founder of the dynasty, herself was a refugee. She saw Poole disappear into time, collapsing the wormhole links. And when the way home was lost, Shira was stranded. But she did not abandon the Project."

"The Project?"

"Shira belonged to a philosophico-religious sect called the Friends of Wigner. And their purpose in coming back in time was to send a message to a further future yet ... "

Kale, frustrated, had to endure more of this peculiar philosophising.

Life, Shira said, was essential for the very existence of the universe. Consciousness was like an immense, self-directed eye, a recursive design developed by the universe to invoke its own being—for without conscious observation there could be no actualisation of quantum potential to reality. And if this were true, the goal of consciousness, of life, said Shira, must be to gather and organise data—all data, everywhere—to observe and actualise all events. In the furthest future the confluences of mind would merge, culminating in a final state: at the last boundary to the universe, at timelike infinity.

"And at timelike infinity resides the Ultimate Observer," Shira said quietly. "And the last Observation will be made." She bowed her head in an odd, almost prayerful attitude of respect. "It is impossible for us to believe that the Ultimate Observer will simply be a passive eye. A camera, for all of history. We—the Friends of Wigner, the sect to which Shira belonged—believe that the Observer will have the power to study all the nearly-infinite potential histories of the universe, stored in regressing chains of quantum functions. And that the Observer will select, actualise a history which maximises the potential of being. Which makes the cosmos through all of time into a shining place, a garden free of waste, pain and death."

She lifted her head abruptly, and the light from the logic pool struck shadows in her face. She was quite insane, Kale thought.

"It is essential that humanity is preserved in the optimal reality. What higher purpose can there be? Everything the Friends did was dedicated to the goal of communicating the plight of mankind to the Ultimate Observer. Even the destruction of Jupiter. And even I, stranded here in this dismal past, stranded out of time, have always struggled to do what I could to progress the mighty project." She peered into the logic pool. "I, in my way, am searching . .. "

He stared at her. "Ma'am—you said 'we'. You speak of yourself as a Friend of Wigner. Not the first Shira."

She lifted her face, its skin papery.

"You are Shira. The first. There was no dynasty, no thirty-two Shiras, mother and daughter—just you, the first, living on and on. My, you must be nine hundred years old."

She smiled. "And yet I will not be born for another four hundred years. Am I old, or young, Admiral? Once the Poole wormhole was closed down I had lost my route back to the future. I accepted that. But there was always another way back. The long way. I accepted AntiSenescence treatment. I began to accrue power, where I could. And then—"

"And then," said Kale, barely believing, "it was a simple matter of living through fifteen centuries—fifty generations—and waiting for your time to come again."

"You have it, Admiral."

He peered at her. "Were there others like you—others stranded in history?"

"None that remain in Sol system." Her face was blank. "None that survive."

"You monopolised knowledge of the future to cement your power base." He remembered himself. "Ma'am, forgive me for speaking this way—"

"It's all right, Admiral. Yes, you could put it like that. But it was necessary. After all there had been no unified government of mankind, none before me. Quite an achievement, don't you think? Why, I had to invent a religion to do it ... It was necessary, all of it. I need the shelter of power. There are many obstacles to be overcome in the decades ahead, if I am to survive to the year of my birth."

"Ma'am—I thought I knew you."

"None of you knows me, none of you drones." She withdrew. "I tire now. Progress your war, Admiral. But we will speak again. Even if I fall, the Project must not fail. And I will entrust in you that purpose."

He bowed to her. "Ma'am." And with huge relief he left the chamber, leaving the lonely woman and the light of the logic pool behind him.

AD 4820

S-Day plus 9

Jupiter

The earthworm fleet was assembling here too, somewhere on the far side of the giant world. The showdown was still hours away, the Alphan planners believed.

Despite the urgency of the situation, despite all Flood's urging and imprecations, every chance they got the crew of the Freestar stared out of their lifedome at Jupiter. After all there were no Jovians in Alpha system.

It was a bloated monster of a world, streaked with autumn brown and salmon pink. And, still more extraordinary, it was visibly wounded, immense storms like funnels digging deep into its surface. The other ships of the rebel fleet, the other five of their minuscule armada, drifted across the face of the giant world, angular silhouettes.

One other structure was visible in its own orbit, deep within the circle of the innermost moon, Io. It was an electric-blue spark, revealed under magnification to be a tangle of struts and tetrahedral frames. This was the Poole hub, where Michael Poole had used the energies of a flux tube connecting Jupiter to Io to construct the heart of his intrasystem wormhole network. Even today one of those ancient Interfaces linked Jupiter itself to Earth—or it had until the earthworms had cut it.

It was an extraordinary sight, Flood conceded. "Spectacle and history, all mixed up."

"Yes, dad," said Beya. "You know I've been reading up on Sol system history ... "

He did and he didn't entirely approve; it struck him as a guilty reflex.

"You say this is all because of human action?"

"That's the story," he said. "Though my grasp of ancient earthworm history is shaky."

Nine hundred years before, Jupiter had been wrecked by the actions of the Friends of Wigner, rebels from a dismal, alien-occupied future. The Friends had had in mind some grand, impossible scheme to alter history. Their plan had involved firing asteroid-mass black holes into Jupiter.

"Whatever these 'Friends' intended, it didn't work," Flood said. "All they succeeded in doing was wrecking Jupiter." He shook his head. "The greatest mass in Sol system after the sun itself, a vast resource for the future—ruined in a single action. How typical of earthworm arrogance!—"

Light sparked in the complex sky. Flood saw it reflected in his daughter's face. He turned.

One of the rebel ships, the Destiny of Humankind, had exploded. The delicate spine was broken, the detached GUTdrive flaring pointlessly, and the fragile lifedome shattered, spilling particles of pink and green into space.

Alarms howled. Virtual control desks appeared before Beya and Flood, crammed with data. The crew, sleepy, shocked, scrambled to get to their positions.

And then another ship detonated. The Future Hope, a ship five hundred years old, gone in a second. This time Flood glimpsed the missile that took it out. But there was no time to reflect.

"Incoming," Beya called. "Incoming!"

Flood worked at his desk with brisk sweeps of his fingers. "All right. We're evading." The lifedome shuddered as the GUTdrive flared, shoving the Freestar sideways.

A missile streaked past the lifedome, close enough to see with the naked eye, glowing white-hot.

"Shit," Beya said. "How are they doing this? The scans showed a volume around us was clear."

"Jupiter," Flood said, reading his displays rapidly. "The missiles are coming out of Jupiter. But the velocities are so high—I don't understand."

"The black holes," Beya said. "Maybe that's it. They're slingshotting their missiles off the central black holes. You can pick up a hell of a lot of kinetic energy from an ergosphere."

"And they're punching out of the carcass of the planet, right at us. Incredible."

Another ship flared and died, a flower of light pointlessly beautiful.

"The Dream of Alpha," Flood read. "That's three of us gone in a few seconds. They're picking us off. Three of us left, against a dozen Navy cruisers. We'll have to withdraw. Regroup if we can—"

"No." Beya was working hard at her desk. "Dad, there's no time for that. Tell the survivors to make for the Poole hub."

"Why? The wormhole links are severed; we can't get away from there."

"It will give us a bit of cover. And I've an idea," she said, distant, working.

Flood frowned. He didn't enjoy it when this determined side of his daughter showed itself; it made her seem too strong, too independent—he couldn't protect her any more. But she had called the black-hole missile manoeuvre correctly. He saw no better option than to accept her recommendation. He snapped out the orders.

The Freestar's GUTdrive kicked in. The acceleration mounted quickly, two, three, four gravities. Flood felt it in his bones, but he stood his ground, determined. Above his head, Jupiter slid with ponderous slowness across his field of view. "Come on," he said. "Come on ... "

Elsewhere, aboard the bridge of the Navy ship Facula, there was much cheering at the downing of half the rebel fleet—premature cheering, as far as Stillich was concerned.

"Status," he yelled at Pella, above the noise.

"Three down, three to go."

"But the three survivors aren't running."

"Not from Jovian space, no sir. They seem to be making for the Poole hub."

"Why there?"

Pella tapped a desk. "The war-game AIs have no idea. If they need cover they could run to one of the moons ... " She grinned. "Sir, who cares? We have twelve ships against three. We can shoot them out of the sky."

Stillich felt deeply uneasy, but he couldn't argue with that analysis. "Well, that's the idea, Number One. All right. Call the fleet; set up an attacking perimeter."

"Sir."

The GUTdrive surged smoothly.

Twelve ships against three. The decision to withdraw the Sol fleet to Jupiter had been a good one, Stillich thought. The hinterland of the giant planet was a dangerous, complex place, laced with strong gravitational fields, intense radiation and hazards like the Io flux tube. It was a battleground much more familiar to the defending Navy than to the attackers—and he had been impressed by the innovative thinking at a Navy college on Earth that had come up with the notion of using the black hole slingshot to pick off the rebels even before the ships had engaged.

But once he had accepted the stratagem, Stillich had argued for withdrawing all of Earth's fleet to Jupiter or its environs, not to leave half of it mounting a futile picket fence at the incoming relativistic wave. Twelve against three. It was more reassuring than twelve against six had been, but Stillich was in no mood for anything less than a complete victory, an annihilation, the security of the system demanded it, and the more overwhelming the odds the better.

On the Freestar, the Poole hub was already approaching, a cluster of Interface portals hurtling over the horizon towards the surviving rebel ships, a tangle of electric blue.

"Lethe," Beya breathed. "I didn't know how beautiful it was."

Flood said softly, "The wormholes are gateways to other times, other places. They should be beautiful, like all great engineering."

Alarms chimed once more.

Beya studied her data desk. "They're closing in, dad, a dozen Navy cruisers."

"Then this is it." He clenched his fists. "Let's at least back up against the wormhole hub. Have the AIs war-game an optimal configuration—"

Beya kissed him on the cheek, a lingering gesture that still felt too brief. "Cover me."

"What?"

She turned and ran, faster than he could hope to catch her. "I told you I have an idea." And she ducked out of sight, through a hatch to the ship's spine.

A missile soared past the lifedome, and the crew ducked, involuntarily. Then there was a speckle of laser light, and the dome blister blacked itself out. Grey Morus, Flood's second in command, yelled across, "They've got our range, Flood. We're shooting back but—"

Flood's data desk chimed. The AIs had come up with a defensive configuration for the ships, lifedomes together, tails out, backed up against the Poole hub, using superhot GUTdrive exhaust for defence. "Copy this and implement," he snapped at Grey. He punched his data desk. "Beya! Where are you?"

In Beya's flitter, her father's voice was as clear as if he was riding alongside her. Beya was determined to keep her voice level. "Can't you see me, dad? I'm up around your ten o'clock—oh, but your blister is blacked out."

"What the hell are you doing up there?"

The flitter ducked sideways, jolting her against her restraints. "I'm taking fire, that's what I'm doing. Dad, if you've got a spare laser, cover me!"

Now the flitter swept around. She was heading straight for the Poole hub, a tangle of wormhole mouths, powder blue. She saw the three ships of the invasion fleet backing up, pirouetting clumsily into their defensive position. But the Navy ships swept across her view, soulless, mechanical, spitting missiles at the rebels, bathing them with laser light. There were so many of them, a dozen against three.

And as she watched a Navy missile got through, hammering into the GUTdrive pod of the Mercy and Tolerance. Slowly the great ship began to drift out of position. But even as she did so she spat fire in Beya's direction, and picked a Navy missile out of the sky.

"Thanks, Mercy/' she whispered.

"You're welcome/' came a reply.

"Beya, what are you doing?"

"Dad, do you trust me?"

"I—You know I do. What kind of question is that?"

"Well enough to gamble your life on my say-so?"

"I may not have a choice. If you'd just tell me—"

"Just another bit of Sol system history, dad. Something I read, an incident at a planet called Pluto, long ago ... " She stared out at the dazzling sky-blue of the nearest portal's exotic-matter tetrahedral frame. The faces were like semitransparent panes of silvered glass; she could make out the watercolour oceans of Jupiter, swirled around in a fashion the eye could not quite track, like visions in a dream. "So beautiful."

"Beya?"

The flitter turned its nose straight towards the Interface. She ran a quick calculation on her data desk.

"Five seconds, dad."

"Until what?"

"Fire up on my mark, and get out of there with everything you have."

She passed through the glimmering face as if it did not exist, and now she was inside the blue frame of the Interface.

Her father's voice was distorted. "Beya, please—"

"This is for you, for mum, for Alpha. Remember me. Mark!" And she stabbed down her finger at her data desk.

The flitter's engine exploded. Something slammed into her back. Electric-blue light flared all around her.

Remarkably, she was still alive.

She was jammed up in the little ship's cabin, which had been ejected from the wreck. She made herself look around. She gasped with the pain of broken bones.

There was something wrong with space. A ball of light, unearthly, swelled up behind her, and an irregular patch of darkness ahead was like a rip in space. Tidal forces plucked at her belly and limbs. Nobody had had a ride like this in a thousand years.

And she saw Navy ships scattered like bits of straw in a wind.

The tides faded. The darkness before her healed, to reveal the brilliance of Sol. And the flitter cabin imploded, without fuss.

It took long minutes before the crew got the tumbling of the Facula under control.

Pella came to Stillich, her brow bloodied. "Damage report—"

"Never mind that. What just happened?"

"An Alcubierre wave."

"A what?"

Pella dragged her fingers trough mussed hair. "Captain, a wormhole is a flaw in space. It's inherently unstable. The throat and mouths are kept open by active feedback loops involving threads of exotic matter. That's matter with a negative energy density, a sort of antigravity which—"

"What's an Alcubierre wave?"

"Something exploded inside the Interface. And the Interface's negative energy region expanded from the tetrahedron, just for a moment. The negative energy distorted a chunk of spacetime. The chunk containing us."

On one side of the wave, spacetime had contracted like a black hole. On the other side, it expanded—like a re-run of the Big Bang, the expansion at the beginning of the universe.

Pella scanned her data desk. "We lost contact altogether with five of our ships. None of the ships is operational. The Facula—"

"What about the surviving rebels?"

"Two disabled." She looked up. "One got away. It's heading for Earth."

"Can we give chase?"

"No, sir, we—"

"Get me a line to Admiral Kale. Patch it through to the Palace if you can—"

She looked up again, shocked. "Sir. I've a standing order, to become operative in case of failure."

"Get on with it."

"You're relieved of command. In fact, you're under arrest."

Stillich laughed. "Fine. I'm in your custody, Number One. Now get hold of a working flitter and get me back to Earth."

AD 4820

S-Day plus 11

Orbit of Neptune

The final attempt to stop the Fist ships was the most dramatic.

After ice-moon debris had put an end to One and then Four, it was a GUTship that tried to halt the last two survivors, Three and Two. Not far within the orbit of Pluto, on the rim of Sol system proper, moving at a fraction of the attackers' near-lightspeed, it tried to ram them. It was an extraordinary bit of relativistic navigation. Fist Three, taking the lead, destroyed it with an equally remarkable bit of sharp-shooting. But the detonation hurled debris into the path of Three, and that was that.

When it was done, here was Fist Two alone, sailing on through the orbit of Neptune at over ninety-eight per cent of lightspeed—the fastest velocity ever attained within the system, it was believed, save for cosmic rays, atomic nuclei ejected from supernovas.

Fist was a warship, a relativistic weapon, manned, sailing among the fragile worlds of the mother system. It was wrong, Densel Bel thought. It was monstrous. And yet here he was. Densel Bel was glad the remaining time was so brief.

AD 4820

S-Day plus 11

Imperial bunker, New York City

Stillich was brought to the Empress's bunker in shackles.

Admiral Kale was here. With an impatient command he ordered the shackles removed, and dismissed the guard.

Beside the logic pool, in its eerie, shifting light, the Empress brooded. Some Virtual display was playing itself out before her: a globe, a point of light, a glowing splinter—over and over.

Stillich approached his superior, rubbing his ankles. "Sir. How long?"

Kale snapped his fingers; a small Virtual data display appeared in the air. "That fucking relativistic ship is crossing Saturn's orbit."

Stillich thought. "Seventy-eight minutes from Earth."

"About that. And we're still waiting on this bastard Flood."

After the Navy's scattering at Jupiter, there had been nothing left to stand in the way of the Freestar's advance on Earth. At last the rebel ship had entered orbit around Earth itself, and Flood was descending to discuss surrender terms.

"Do you think we've a choice but to do what he says?"

Kale grimaced. "The choice is playing itself out on the Empress's lap."

The consequence of the Fist striking the Earth had been modelled for the Empress. The physics was simple, a function of the fist's immense kinetic energy. The impact, marked by a tunnel of air shocked to superheated plasma, would be the source of a pulse of electromagnetic energy itself strong enough to sear anything alive across half a hemisphere—bright enough to pierce walls. The shock waves of air and water that would follow, and a hard rain of melted bedrock falling from the sky, would do the rest. Shira watched this over and over, obsessive.

At the seventy-minute mark, the chamber door opened. Flood walked in. He was a bulky, strong-looking man, wearing a simple tunic and leggings. He carried a package, a sleek black box. Two others accompanied him, a man and a woman similarly dressed. These companions looked nervous, even over-awed, to be in this bunker under New York City itself, to be in the presence of an Empress. Flood, however, showed no fear.

Flood glanced at the Empress. She showed no reaction, watching her model go through its sequence, over and over.

Kale sneered. "So you are Flood, the great rebel leader. And you dress like a farmer. How ostentatious. How predictable."

Flood smiled at him, and looked him up and down. "Nice jacket. Here. Hold this." He handed him the box he was carrying.

Kale took it reflexively. Then, irritated, he passed it to Stillich. "What is it?"

"Our final weapon. A nanotech modification of the smart plague—hardware, not software. Released, it would chew up the robust networks you were prudent enough to install—your optical-fibre links and all the rest. Necessarily delivered after landfall."

Stillich put this on the floor, gingerly. "Your final weapon save for the fist."

"Save for that, yes."

"Why have you brought it here?" the Admiral asked. "You have won. You have no need to do more damage."

Flood walked to the rim of the logic pool. "To put an end to that."

Now the Empress spoke. "You are Flood."

He bowed. "Empress—"

"Shira will do."

"Yes. Shira is your name. It always was, wasn't it? I am here to discuss terms."

Stillich said tensely, "Keep it brief, farmer. We don't have much time."

"Brief I can manage. Your Empress must stand down. This logic pool must be shut down—here, now, immediately, before my eyes. And we begin the establishment of a constitutional convention. A new relationship between the free worlds of all mankind."

"How civilised," Kale said. "A constitutional convention, or global obliteration."

"Admiral," Stillich snapped. "We don't have the time. Flood—why the logic pool? This is at the centre of everything, isn't it?"

Flood faced Shira. "The centre of all she is doing. Isn't that true, ma'am?"

"How little you understand," Shira said.

"Oh, I think I understand well enough." Flood faced the Navy men. "You know her story by now. She is a refugee from the future—from a time that, even nine hundred years later, is so far remote it remains the future. And she is going home the long way, year by year, heartbeat by heartbeat. But it isn't the future she longs for - is it, Shira? You don't want to be in this universe at all ... "

Kale had tried to explain Shira's extraordinary ideas to Stillich, and Stillich thought he understood. "Ma'am? Is he right?"

"None of this is real," Shira said, her voice a husk. "It is all transitory. We are simply forced to endure the motion of our consciousness along one of the chains of quantum functions, a sequence of potentiality to be collapsed, discarded, by the Ultimate Observer at timelike infinity ... "

Stillich tried to control his impatience. "This is just anachronistic philosophy. I don't see what it is that she's doing here that disturbs you, Flood."

"She longs for her Ultimate Observer. And she thought she could find her quantum messiah in mathematics ... "

The logic pool, he said, was a meta mathematical universe. While not infinite it comprised more mathematical understanding, far more, than had yet been explored by mankind—and in principle, somewhere within the meta mathematical branching of the pool, any algorithm possible might exist.

Shira said softly, "All our science is based on the search for simple rules underlying complex phenomena. Simple algorithms can be shown to generate complexities, from the turbulent flow in a glass of water to the spiral structure of the Galaxy itself."

"You see the idea," Flood said. "There's a lot of nonsense in there, but also a lot of treasure to be dug out. It's as if you have a tank full of every possible combination of words in Earthish. Most of it is dross. But in there to be discovered are the finest works of human literature—even those not written yet."

"And similarly, I suppose," Stillich said, "scientific understanding not yet acquired."

"Well, yes. But Shira has always been more ambitious than that, haven't you, Empress?"

Shira said, "Human consciousness is likewise the product of simple algorithms with particularly complicated outcomes. And similarly, any mind imaginable—human, post-human or alien—must be there to be discovered, in the pool, in metamathematical stasis."

Flood grimaced. "The Friends of Wigner were prepared to destroy Jupiter to send a message to the Ultimate Observer. Now this lunatic believes she can find the Observer in a tank of light."

"Show some respect," Stillich said sharply.

"But whether or not she ever achieved her goal, she is in danger of unleashing much greater threats on humanity. For some of the minds in there are not content with stasis, with waiting to be discovered. Look at this." He summoned up a Virtual of his own. "We've been tracking this for years. Decades. We have our spies, in Sol system. Look at this. It's a neutrino scan we made from the Freestar just hours ago."

It took Stillich a moment to work out that he was looking at a cross-section of the Earth, deep below the granite raft of Manhattan, and the imperial bunker. And down there, swimming in the mantle, was a shape, perhaps organic, perhaps artificial, a winged shape like a stingray, like a sycamore seed.

"It isn't fully formed," Flood said grimly. "Not fully operational. But it soon will be."

Kale asked, "What is it?"

"In the Friends' accounts of their dark future, there are hints of a race even more threatening to mankind than the occupiers of Earth from whom they fled. A race called—" His pronunciation was uncertain: “Chee-lee, Zee-lee. They, or their potentialities, are lurking in the logic pool. And they are trying to break out."

"How?" Kale snapped. "By constructing this ship, deep in the Earth? How are they doing that?."

"We have no idea," Flood said. "Our only concern was to stop it, before this ship bursts from the Earth like a bird from its egg. I mean, this is a threat so potent it is trying to strike at us out of nothing more than a statement of the logical possibility of its own existence! If this thing had got out of the mantle, I don't imagine our four light years' separation would have saved Alpha system. Now do you see why it was necessary to wage this war? It wasn't just for our freedom from Shira's political domination. It was to free all mankind of this terrible threat—for Shira, your Empress from the future, was endangering all of us."

Stillich looked at the Admiral's grim face.

"Decision time," said Kale.

"Yes, sir. My view? It's not worth risking Earth to save this project of the Empress's—"

"The Project is worth any price," Shira murmured. "Even that."

Kale turned to her. "Ma'am—we have no time. We must accept his terms. We can discuss the details of your abdication later—the legitimisation of an interim government ... " He turned to Flood. "You have won, star-farmer."

Flood picked up the nanotechnological box, and dropped it in the logic pool. It sank with barely a ripple, and then seemed to dissolve. Flood watched the pool, as the writhing metamathematical bifurcations withered, and the pale light began to die. "It is done."

Stillich said urgently, "And call off your relativistic attack dog."

Flood smiled. "Done."

"None of this is real," Shira murmured. She rolled back into the shadows.

Kale faced Flood. "You will pay for all you have done."

Flood gazed at him, his eyes full of regret. "Oh, I have paid, soldier. Believe me, I have paid."

And then the bunker shuddered, and a wave like a tide pulsed through Stillich's gut.

Kale staggered. "What was that?"

When Stillich had recovered, Shira was gone.

AD 4820

S-Day plus 11

Asteroid Belt

Earth was so close now that Densel Bel could see it, an image magnified and heavily corrected for relativistic distortions, suspended over his head—he could see it in real time, a blue marble, achingly beautiful, and yet scarred by war. But he could never touch it. The vast pulse of kinetic energy that had been injected into this ship by years of GUTdrive acceleration separated him from his home world just as much as if he had been stranded in another universe.

Only subjective minutes remained before his life ended, and Earth died with him.

Once more Flood appeared before him. "It's over," he said, smiling.

"What is?"

"The war. Shira is abdicating—we are free. Now you must destroy the Fist Two."

"Me? Why me?"

"This was your purpose, Densel Bel. You are my failsafe. I needed somebody on board who I knew would terminate the mission, even at the cost of his own life. And that's you, a man loyal both to Earth, where you were born, and Footprint, where you have your family. You have the authority. Just say aloud, 'let it end'. The AI will do the rest. Goodbye, Densel Bel. I hope you feel the sacrifice you are making is worth it."

"Flood. Wait—"

"Yes?"

"Would you have done it? Would you have let the Fist strike the Earth?"

"Oh, yes. To stop what Shira was doing—believe me, there was no choice. Good luck, Densel Be!." He broke up into a cloud of pixels and disappeared.

Densel Bel looked up at the blue Earth, and thought of Su-su and Fay. "let it end."

Light flared, an instant of intense white pain—

AD 4820

S-Day plus 7 months

Earthport

The flitter rose from Earth like a stone thrown from a blue bowl. The little cylindrical craft tumbled slowly as it climbed, sparkling.

Peering out from the rising flitter, Stillich had to admit that the Freestar, which he had come to inspect on behalf of the Navy, looked spectacular, with the newly constructed wormhole Interface, a bright blue tetrahedron with milky-gold faces, slung beneath its angular spine. When Flood and his crew returned to Alpha system in a couple of months, they would take the grudging good wishes of Earth's interim government with them, and the business end of a new wormhole, which would link the worlds of Alpha and Sol forever.

"Or until the next political crisis," Flood said dryly.

"There is that."

"Look—here comes another shipment of green muck from Titan."

It was a cargo pellet slung from Titan that had crossed the system unpowered, and now made an entry into Earth's atmosphere, cutting a bright contrail across the blue sky. This crude shipment method was an interim emergency measure, until the great space elevators were hung in the sky once more.

"Not 'green muck'," Stillich said. "Algal concentrate."

Flood pulled a face. "Next time you visit Footprint, be my guest at dinner."

"That might be some time away," Stillich said gently.

They both knew that was likely to be true. Too many had died, on Earth and elsewhere, for the populations of Sol system to forgive their colonial cousins for the war, whatever the retrospective justification in terms of Shira's murky crimes.

But it would come in time, Stillich knew. Already Earth was recovering, as people and machines laboured to repair the damage done, and the vast resources of space were reattached to the damaged planet. And likewise Sol system was making conciliatory gestures to the starborn. The Facula was en route back to Tau Ceti, taking the abducted colonists home. Stillich had made sure Pella was on that mission. She was a bright officer, but she needed to acquire the humanity that informed good judgement

"I saw your report on Shira's escape," Flood said now. "You were serious in your conclusions?"

"There's no real doubt about it." Shira had stashed many treasures from her lost future down in that bunker, and among them was what appeared to be a transdimensional transport system: Shira had disappeared from the bunker by stepping sideways into one of the universe's many extra compactified dimensions. "If that doesn't qualify as a 'hyperdrive' I don't know what does."

Flood shook his head. "She had a hyperdrive. And she kept it to herself all these centuries, while the rest of us limped across the Galaxy in sublight GUTships. Just so she had a last-resort escape hatch. How selfish."

"Maybe it's just as well. Anyhow I guess we are due to acquire the technology in a few centuries. Certainly it will transform the face of war." Stillich and Flood were both key witnesses at an inter-governmental inquiry into the course and conduct of the war, an experience Stillich suspected had increased both their understandings. "When you think about it, an interstellar war fought out with sublight drives is right at the limit of the possible. For a start you need a strong reason to do it; almost nothing is worth fighting such a campaign for."

Flood grunted. "You should read more history. Our fear of what Shira was up to was comparatively rational as a casus belli. Another global threat, experiments with vacuum energy, which could destabilise the entire universe, say, might be another. But horrific wars have been fought over splinter-fine differences in ideologies. look up the crusades some time."

"But when we get hyperdrive," Stillich said, "and as a consequence—perhaps—we get an authentic first alien contact, rather than these dark hints and glimpses from the future, we might soon see a transformation both of our means of fighting war, and of our choice of opponents. This might be remembered as mankind's last great conflict."

"The end of human war?" Flood laughed. "I knew you were imaginative, Stillich. I didn't have you down as a dreamer ... "

An alarm chimed, as the flitter prepared to dock with the Freestar. Stillich straightened his uniform, preparing for duty.

As it turned out, Flood was wrong.

It was only a few years later that Pella, en route to Tau Ceti, sent Stillich a packet message to announce contact with an alien species. He took the call in his apartment in the clouds over London.

"As far as we can tell they are aquatic group-mind multiple creatures. Fish-like. They have an interstellar network of trading colonies. Their name for themselves"—a thin squeal, heavily processed from the creatures' own sounds, 'Ss-chh-eemnh'—means something like the Wise Folk. Rather like Homo sapiens. Captain, here's the thing. They were heading for Sol system! They picked up some kind of signal from Shira's escape. The hyperdrive she used must have been one of their drives, or a human derivative. The question is, sir, how our descendants managed to take such a prize away from the Ss-chh-eemnh ... "

Everything was different, then, Stillich thought; this was a discontinuity in human history. He looked away from the busy bowl of the city, to the silent stars, wondering what came next.

Table of Contents

STARFALL

AD 4771

Starfall minus 49 years

Between Sol and Alpha Centauri

AD 4801

Starfall minus 19 years

Tau Ceti

AD 4814

Starfall minus 6 years

Armonktown, Footprint. Alpha System

AD 4815

Starfall minus 4 years 8 months

Sol System

Starfall minus 4 years 5 months

Alpha system

AD 4819

Starfall minus 1 year

Sol System

AD 4820

Starfall minus 2 months

Sol system

August 11th, Starfall Day

Sol system

S-Day

London

S-Day plus 3

Sol system

S-Day plus 4

Solar orbit

AD 4820

S-Day plus 4

Oort Cloud, outer Sol system

S-Day plus 6

Imperial bunker. New York

S-Day plus 9

Jupiter

S-Day plus 11

Orbit of Neptune

Imperial bunker, New York City

Asteroid Belt

S-Day plus 7 months

Earthport