Xeelee: An Omnibus: Raft, Timelike Infinity, Flux, Ring

by Stephen Baxter

  ‘Essentially. Except that you’re talking about the first few fractions of a second ...’

  ‘GUT’ stood for ‘Grand Unified Theory’, the philosophical system which described the fundamental forces of nature as aspects of a single superforce. The heart of the Crab’s GUTdrive was a fist-sized chunk of hydrogen locked into a superconducting bottle and bombarded to creation physics temperatures. At such temperatures only the unified superforce could act. When hydrogen was bled from the bottle the superforce went through ‘phase transitions’, decomposing into the four familiar forces of nature - strong and weak nuclear, gravitational and electromagnetic.

  And, just as steam releases heat when it goes through a phase transition by condensing to water, so at each transition of the superforce a pulse of energy was emitted.

  Poole said to his father, ‘The Crab uses GUT phase energy to flash comet ice to plasma; the superheated plasma is expelled through a superconducting nozzle ...’

  Harry nodded, peering down the mile of superstructure to the residual lump of comet which had brought them in from the Oort Cloud. ‘Sure. But it was that same phase transition energy, liberated during the cooling period after the Big Bang, which drove the expansion of the universe itself.

  ‘That’s what seems so awesome, when you stop and think about it, Michael. We’ve spent a year scooting around the Solar System - and now we’re making Jupiter himself cast a shadow - and we’re doing it by harnessing the energies of creation itself. Doesn’t it make you wonder?’

  Poole rubbed the side of his nose. ‘Yes, Harry. Of course it does. But I don’t actually think that sort of attitude is going to help us all that much, in the next few days. I’d rather not feel awed by the workings of our own drive, right now. Remember we’re going to be dealing with humans from fifteen centuries into the future ... or for all I know, with artificial life forms, or with aliens, even.’

  Harry leaned closer to Poole and grinned. ‘Not all of us AI are such terrible things, Michael.’

  Poole narrowed his eyes. ‘Push your luck and I’ll pull your plug.’

  Harry grumbled, ‘Maybe these superpeople from the future will be advanced enough to recognize the rights of AIs. Such as the right to continuous consciousness, for instance. Anyway, I know it’s all talk.’

  ‘If you don’t get your fingers out of my head then I’ll shut you down, talk or not, you old fart.’

  An alarm chimed through the lifedome. The Crab, sailing barely a thousand miles over a sea of purple clouds, was near its closest approach to the planet; and now the battered old ship swept around the limb of Jupiter and emerged into the light of the distant sun. Sol, shrunken by distance, lifted its rays through layers of cloud at Jupiter’s flat-infinite horizon; there was a dazzling impression of the depth of the Jovian atmosphere as clouds cast thousand-mile-long shadows over each other. The cabin was flooded with brilliance. For a second Harry’s Virtual image retained the purplish shadows cast from the cabin floor by the drive. Then the processor caught up and when Harry turned his face to the sun his profile was highlighted in yellow.

  Then, like the rise of a second, angular sun, the Interface portal hurtled over the horizon towards them. Michael could see the firefly sparks of ships circling the portal, waiting for any new intrusion from the future. The Crab’s trajectory took her to within a few dozen miles of the portal; Michael stared out at the dazzling sky-blue of the portal’s exotic tetrahedral frame, let his eyes linger over those cool lines and be drawn effortlessly to the geometrically perfect vertices. The faces were like semitransparent panes of silvered glass; he could make out the watercolour oceans of Jupiter through the faces, but the cloud images were overlaid with a patina of silver-gold and were distorted, they swirled around in a fashion the eye could not quite track, like visions in a dream. And every few seconds a face would abruptly clear, just for a dazzling moment, and afford Michael a glimpse of another space, unfamiliar stars, like a hole cut into Jupiter.

  The Crab swept on and away from the artifact; it dwindled rapidly behind them like an abandoned toy.

  ‘My God,’ Harry breathed. ‘I didn’t know how beautiful it was. I thought I could see stars in those faces.’

  ‘You could, Harry,’ Poole said softly. ‘It really is a gateway to another time, another place.’

  Harry leaned towards Michael. ‘I’m very proud of you.’

  Poole stiffened and pulled away.

  Harry said, ‘Listen, what do you really think we’re going to find out here?’

  ‘Aboard the craft from the future?’ Poole shrugged. ‘Since they haven’t communicated with us apart from that single message from Miriam when they came through the Interface a year ago, it’s difficult even to extrapolate.’

  ‘Will humans still be recognizably human, do you think?’

  Poole swivelled a glare at Harry. ‘And are we “recognizably human”? Look at us, Harry; I’m an AS-immortal, and you’re a semi-sentient AI.’

  ‘Semi-sentient?’

  ‘Superficially we look human enough, and we’d probably claim to be human, but I don’t know if a man of, say, a thousand years ago would recognize us as members of the same species as himself. And now we’re talking another fifteen centuries down the road ...’

  Harry wiggled his fingers in the air, pulling a face. ‘A third arm growing out of the centre of the face. Disembodied heads, bouncing around on the deck like footballs. What do you think?’

  Poole shrugged. ‘If gross modifications like that are efficient, or serve a purpose, then maybe so. But I don’t think any of that matters a damn, compared to what’s going on inside their heads. And what they’ve built.’

  ‘What about technology?’

  ‘I guess I’d put singularity physics a long way up the list,’ Poole said. ‘The manipulation of spacetime curvature . . . We’ve already got a mastery of high-density, high-energy physics - that’s the heart of the GUTdrive, and of the exotic matter which the Interface portals were built of.’

  ‘And in fifteen more centuries—’ Harry prompted.

  ‘How far could we take this? I’d anticipate the manufacture of singularities themselves, on the scale of a few tons up to, maybe, asteroid masses.’

  ‘What for?’

  Poole spread his hands wide. ‘Compact power sources. If you had a black hole in your kitchen you could just throw in the waste and see it compressed to invisibility in a fraction of a second, releasing floods of usable short-wavelength radiation. And how about artificial gravity? Bury a black hole at the centre of, say, Luna, and you could raise the surface gravity as high as you like.’

  Harry nodded. ‘Of course you’d have to find some way of keeping the singularity from eating the Moon.’

  ‘Yeah. Then there are gravity waves, to be generated by colliding black holes. You could build tractor beams, for instance.’ Poole settled back into his couch and closed his eyes. ‘Of course, if they’ve taken this far enough, maybe they will have found some use for naked singularities.’

  ‘And what’s a naked singularity?’

  ‘ ... Maybe we’re going to find out.’

  Now they were entering a region of space filled with ships; hundreds of drive sparks flitted over the patient ocean of Jupiter. The ships were too distant to afford any detail, but Poole knew that there must be Navy ships from the inhabited Jovian moons, science craft from the inner Solar System, and God-damned tourists and rubbernecks from just about everywhere. A subdued chatter in the background of the lifedome told him that signals were starting to come in from that motley armada - since the receipt of Berg’s message a year earlier, Poole knew, Jovian space had been the centre of attention for most of the human race, and his own arrival here had been the most eagerly anticipated event since the emergence of the future ship itself.

  He ignored the messages, letting Virtual copies of himself handle them; if there was anything devastating they’d let him know.

  Peering into the crowded space ahead, and after his decades of is
olation in the bleak outer lands of the Solar System, Poole felt a pang of absurd claustrophobia. He was driven on by curiosity as well as by a residual concern for Miriam Berg and her crew; but now that his year-long journey in from the Oort Cloud was complete he found he really, really didn’t want to be here, back among the fetid worlds of humankind.

  Harry was studying him, his youthful brow creased. ‘Relax, son,’ he said. ‘It was never going to be easy.’

  ‘Oh, for Christ’s sake, shut up,’ Poole snapped. Even as he spoke he was aware of an odd feeling of relief at having someone, or something, reasonably tangible outside his own head to react to. ‘I should put you in an electronic bottle labelled “Dad”, and take you out when I feel the need of another patronizing fatherly homily.’

  Harry Poole grinned, unmoved. ‘Just doing my job,’ he murmured.

  Now the Crab, drive still blazing ahead of her, was approaching the most dense knot of ships in the sky. The cloud of vessels, as if sensing the approach of the Crab, began to part.

  Inside that firefly mist Michael could make out the lines of something huge, a splash of green against the murky pink of Jupiter.

  ‘That’s it,’ Poole said, finding his voice hoarse. ‘The ship from the future. Time to go to work ...’ He snapped a command into the air.

  The crowded universe outside the lifedome was clouded by a sudden hail of pixels which danced like dust motes around the Crab, slowly congealing into planes, orbs and strands around the lifedome. Harry squirmed in his seat, mouth open, as he watched the huge Virtual take shape around the ship. At last they were looking out through eyes which were each at least a hundred yards wide, with eyelids which swept like rainstorms over the glistening lenses. A nose like a vast engineering project, with nostrils like rocket nozzles, obscured the Crab’s GUTdrive module; and huge sculpted ears sailed alongside the lifedome.

  A mouth, whale-sized, opened moistly.

  ‘My God,’ Harry breathed. ‘It’s you, isn’t it? We’re looking out through your face.’

  ‘I couldn’t think of any other way to be sure we were identified properly. Don’t worry: the Virtual is all show; it’s not even as sentient as you are. It repeats a five-second phrase of greeting, over and over again.’

  ‘So how will they hear what it has to say?’

  ‘Harry, the Virtual is two miles high,’ Poole said, irritated. ‘Let them lip-read!’

  Harry swivelled his head, surveying the nostrils, the cable-like hairs above the cabin, skin pores the size of small asteroids. ‘What a disgusting experience,’ he said at last.

  ‘Shut up and watch the show.’

  Now there were ships all around the camouflaged Crab. Poole recognized Navy ships which bristled with weapon ports, science platforms open and vulnerable, even one or two inter-moon skitters which should surely never have been allowed so close. Many of the larger craft followed the same basic design as the Crab, with drive unit and living quarters separated by a stem; from this distance the ships looked like lighted matchsticks, scattered through space.

  ‘How do you think the men from the future will react to us?’ Harry asked with sudden nervousness.

  Poole, glancing across, saw Harry chewing a nail, a habit he remembered from a distant childhood. ‘Maybe they’ll shoot us out of the sky,’ he said maliciously. ‘What do you care? You’re tucked up in bed on Earth, well away from any danger.’

  Harry looked at him reproachfully. ‘Michael, let’s not go over that again. I’m a Virtual, but I have my identity, my sense of being.’

  ‘You think you do.’

  ‘Isn’t that the same thing?’

  ‘Anyway, I doubt if we’re in any danger,’ Poole said. ‘The future people haven’t made any attempt to use weapons so far; why should they now?’

  Harry nodded grudgingly. ‘True.’ After the future ship had settled into its orbit around Jupiter there had been several attempts by Navy ships to approach the craft. The future humans hadn’t responded, or fired on the Navy ships; they’d simply run away, faster than they could be tracked.

  ‘Maybe they haven’t any weapons,’ Harry said.

  Poole pursed his lips. ‘That’s possible, I guess. They do have their super-drive, though.’

  ‘I know there’s speculation that could be some kind of hyperspace drive,’ Harry said.

  ‘Maybe. But if that’s true we’ve no idea how it works. It’s not possible to extrapolate from existing technologies, the way I speculated about singularity technologies.’

  ‘Maybe it’s not a human invention. Maybe it’s alien.’

  ‘Anyway, I don’t think we’re in any danger of being fired on; and if they want us to come in they’ll not run away.’

  ‘How reassuring,’ the Virtual murmured.

  Now the last few layers of craft peeled away before them, the GUTdrive fire-sparks scrabbling aside like scared insects.

  The future craft was revealed, like a fragment of landscape emerging through a layer of cloud. The Crab’s drive died at last, and Poole’s Virtual, mouthing its idiot words of greeting, loomed over a disc of green Earth a quarter-mile wide. Poole could clearly make out the ring of ancient stones at its centre, like grey-brown scars against the greenery. A belt of anonymous-looking dwellings encircled the stones, and beyond the belt grass grew as in some surrealist’s vision, all the way to the edge of the world; the green of it clashed in his eyes with the purple-pink of Jupiter, so that it was as if the craft were encircled by a scar of indeterminate colour.

  Close to the rim Poole made out a splash of metal, a scarred crater in the grass. Could that be a boat from the Cauchy?

  Sparks of light, like entrapped stars, were sprinkled over this floating fragment of Earth. And here and there Poole could see tiny, insect-like forms crawling across the landscape. People? He imagined faces upturned in wonder to his own vast, smiling mouth.

  He scanned the lifedome’s instrument displays briskly, watching data chatter in on the lifeboat’s mass - about that of an asteroid - and its gravitational configuration and radiation characteristics.

  ‘I’ve seen pictures and I’ve read about it,’ Harry said, ‘but I don’t think I really believed it until now.’

  ‘It looks more fragile than I expected,’ Poole murmured.

  ‘Fragile?’

  ‘Look at it. Why build a timeship under a clod of earth like that, with so little protection? ... Unless, perhaps, you wanted to hide what you were doing.’

  ‘They can run, but they can’t fight,’ Harry said.

  ‘Yeah. Maybe these aren’t the heroic, superpowered gods from the future we anticipated after all. Maybe these people are refugees.’

  Harry seemed to shiver. ‘Refugees from what?’

  ‘Well, at least they haven’t fled from us yet. Come on; let’s get to the boat and see if they will let us land.’

  7

  Michael Poole brought the Crab’s boat down near the grassy lip of the craft from the future, close to the wreckage of a lifeboat.

  Followed by the Virtual of his father, he walked out onto a green plain. For a moment he felt disoriented. Beneath his feet there was grass, the blades coarse enough for him to feel them through the soft soles of his boots; globes the size of his fist hovered eight feet above him, giving off a Sol-like yellow warmth, and towards the centre of the disc-craft a concentration of the globes produced a cosy, Earthlike island of light. There was even a hint of blueness about the layer of atmosphere over the disc of land.

  But above him - like some immense roof over creation - hung the banded clouds of Jupiter. It took a conscious effort not to cringe from that lowering sky.

  ‘You know,’ he said to Harry, ‘I found it quite hard to step out of the boat. I feel naked, standing here.’

  ‘I know what you mean.’ Harry took a deep, theatrical sniff. ‘But the air smells as good as the tests showed it to be. Why, you can even smell the grass growing.’ He bounced on his toes. ‘And near Earth-normal gravity, as we estimated from orbit.�
��

  ‘Quit showing off,’ Poole grumbled. ‘It’s hard to understand how anyone could have the guts to ride through time clinging to this damn thing.’ He thought of Berg huddled against this ground as the broken exotic-matter walls of the wormhole hurtled past her, and he felt an unfamiliar stab of protectiveness. Damn it, Berg could look after herself as well as anyone he’d known - certainly a lot better than he could himself - but nobody deserved to be put through such an experience.

  His protectiveness began to fade to an uncertain guilt, as he wondered if he ought to hold himself responsible, if indirectly, for the chain of events which had resulted in this.

  He watched Harry walk out of sight around the Crab’s boat; the craft, a cylindrical lump of metal still frosted from the chill of space, sat on this plain of grass as incongruous as a bullet on an altar-cloth.

  ‘My God,’ Harry called.

  Poole followed his father. Harry stood, hands on hips, surveying the wrecked lifeboat they’d seen from the Crab.

  The boat had been sliced open like a ripe melon. The laser-strokes through the hull were razor-sharp - almost pleasing in their clarity and neatness. Poole could see how the interior of the craft had been scorched and melted, and how partitions had softened and flowed towards the soil.

  ‘Well, it’s no ordinary wreck,’ Harry said. ‘And look.’ He pointed to an intact hull panel. ‘See the registration?’

  ‘It’s from the Cauchy. Harry, this is Miriam’s boat, it has to be.’ A kind of helpless panic surged through him. ‘What the hell’s been done to her?’

  ‘Nothing, Michael. I’m all right. See?’

  Poole whirled at the sound of the deep, slightly hoarse, and desperately familiar voice. He saw all of her as if in a blur - the tough, lively face, the thatch of cropped hair, eyes that looked soft with tears. Without willing it he found himself in her arms. Miriam was a few inches taller than Michael, and her slim body, encased in a coarse, pink jumpsuit, was tense for a moment, though her arms encirded his back; and then she relaxed, and the length of her body pressed against his. He buried his face in the soft warmth of her neck.