Xeelee: Endurance

by Stephen Baxter

  ‘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 Imperial 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 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. ‘I know of this because I was Ambassador to the court, remember.’

  ‘Ambassador and spy.’

  ‘Yes. Shira must be opposed.’

  Densel felt cold, as if his heart were being stopped by nano-machines once more. ‘You’re going to invade the Solar 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. And you are light years away.’

  ‘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 window.’ 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, so that it was as if he walked even in the absence of gravity.

  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 GUTdrive 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 the Solar System more or less simultaneously. The First Wave is a light-speed viral attack and will actually be the last to be launched. The Second Wave, a 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. The Solar 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 wormhole transit 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 ice to the great interstellar GUTships 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 architectural possibilities of microgravity.

  But many of the buildings were closed, darkened. Frost coated their surfaces, and some of the domes were collapsed. GUTships hung all around this 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 swam towards a cluster of wormhole Interfaces, giant tetrahedra built of struts of electric-blue light. The wormholes to the stars had been cut, but the ancient fast-transit routes within the Solar 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’s recent history. ‘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. The incident was heavily classified, which is why we never heard of it before we got here.’

  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 lethal GUTship came from? Alpha Centauri. Of course Alpha is a pretty common port of origin. It might be coincidence.’

  ‘You’re suggesting this was a deliberate attack, sir?’

  It would fit the wider pattern Stillich was beginning to suspect. He said, ‘Certainly it’s a possibility that might not have occurred to anybody here. I think we have a duty to raise it. 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 from the light storm outside the hull. Stillich took pity on Pella, and let her endure the rest of the transit without distracting her further.

  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 tr
ansit 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, broad and lovely, like a slice of blue 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. Above a green-blue horizon, huge fusion stations sparkled in their orbits. 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, and 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 through 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 revived 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 Stillich 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 pretty much the same.’ 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 interfaces, 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 most people 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 self-adjusting balance between wisdom and innovation.

  To Stillich 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; despite AS technology the old knew they were not. But for the young, twenty-seven years away from home was a long time.

  ‘Have you spoken to your family yet?’ 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 have been dragged 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, however. 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 looked cautiously, without stepping closer. Within the glowing liquid, 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 that is rich enough to contain the axioms of si
mple 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. But he did not live to be charged.’

  ‘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 yourselves. We are here to work.’

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

  The Empress said, ‘You, girl. You were curious about sentience.’

  Stillich admired Pella’s cool as she replied. ‘Yes, ma’am.’

  ‘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 – in fact of logic – 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 breeding tank, Commander. And what it breeds are intelligences constructed of mathematical statements.’