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

by Stephen Baxter

  ‘Spline,’ Berg breathed. ‘They’ll send Spline through. The living ships the Friends described, the warships of the Qax, of the Occupation, come to destroy the earth-craft. Just as we’ve expected.’

  There was an edge in Berg’s voice Poole had never heard before, a fragility that induced in him an atavistic urge to take her in his arms, shield her from the sky.

  Berg said, ‘Michael, those things will defeat the best humanity can throw at them - fifteen centuries from now. What can we do? We haven’t got a hope of even scratching their ugly hides.’

  ‘Well, we can have a damn good try,’ Poole murmured. ‘Come on, Berg. I need you to be strong. Harry, what’s happening in the rest of the System?’

  The Virtual, sharp and clear here outside the tepee, shrugged nervously. ‘I can’t send a message out, Michael. The Friends are still blocking me. But the ships in the area have detected the high-energy particle flux.’ He met Michael’s eyes, mournfully. ‘Nobody knows what the hell’s going on, Michael. They’re still keeping a respectful distance, waiting for us to report back. They don’t see any threat - after all, the earth-craft has simply sat here in Jovian orbit for a year, enigmatic but harmless. What can happen now?’ He looked vaguely into the sky. ‘People are - curious, Michael. Looking forward to this. There are huge public Virtuals, images of the portal and the earth-craft hovering over every city on Earth ... It’s like a carnival.’

  ‘But once the Qax begin their assault—’

  ‘It will be too late.’ Berg took Michael’s arm; her face was still a mask of fear, he saw, but some of her determination, her cunning, seemed restored. ‘Listen to me. The best chance of hitting them is going to be now ... in the first few minutes after the Spline emerge from the portal.’

  Poole nodded. ‘Right. Causality stress.’

  ‘The Spline are living creatures,’ Berg said. ‘Maybe that’s a weakness we can play on; the Qax, and their ships, are surely going to take a while to ramp up to full effectiveness. If we can hit them fast maybe there’s a chance.’

  Berg was right, of course. There was a kind of inevitability to all of this, Poole thought. It’s going to be up to us. He closed his eyes, longing for the silence - the lack of decisions - in the Oort Cloud.

  Harry laughed, his voice brittle and too bright. ‘Hit them fast? Sure. With what, exactly?’

  Poole whispered, ‘With the singularity cannon.’

  Berg looked at Michael sharply, possibilities lancing through her mind. ‘But - even if we get the Friends to agree - the cannon wasn’t designed as a weapon.’

  Michael sighed, looking tired. ‘So we adapt.’

  Harry said, ‘As long as the damn things can be pointed and fired. Tell me how they’re supposed to work. You fire black holes into Jupiter ...’

  ‘Yes,’ Michael said. ‘A pair of singularities is launched in each cannon shot. Essentially the device is a true cannon; once the singularities are launched, their paths are ballistic. Orbiting each other, a few yards apart, the singularities enter Jupiter’s gravity well. The trajectories are designed to merge at a specified point in the body of the planet.’

  Berg frowned. ‘Ultimately the hole, or holes, will consume Jupiter ...’

  ‘Yes. The Project’s design is to render Jupiter into a single, large black hole of a specified mass—’

  ‘But that could take centuries. I know the holes’ growth would be exponential, but still you’re starting from a minuscule base; the holes can only grow as fast as their area allows them.’

  ‘That’s true.’ He smiled, almost wistfully. ‘But the timescale of the Project was longer than centuries; far longer.’

  Berg tried to drag thoughts, ideas from her mind, ignoring the lowering sky above her.

  How could they use this planetbuster cannon to disable a Spline? If they simply shot off black holes, the tiny singularities would pass through the flesh of the warship. No doubt tidal and other effects would hurt the Spline as the holes passed through, and maybe they’d strike it lucky and disable some key component ... but probably not; the Spline was a mile wide and the wounds inflicted by the traversing holes would surely be not much worse than laser shots.

  A multiple strike, a barrage?

  ‘What if we launched two singularities to come to rest at the centre of mass of the Spline? Could we do that?’

  ‘Of course.’ Michael frowned; Berg could almost see trajectory curves rolling through his head. ‘We’d simply need to launch the singularities with a low velocity - below the earth-craft’s escape velocity, essentially.’

  ‘Yes.’ Berg pictured it. Like stones hurled into the air, the singularities would come to rest, hover in the body of the Spline itself ... But only for a moment, before falling back. What good would that do? It would take days for the holes to consume the Spline’s mass - hours, probably, to absorb enough material to inflict any significant damage - not the few seconds they would be present in the volume of the Spline.

  Anyway, they wouldn’t have hours to spare.

  Then what?

  ‘Why would they send the singularities into Jupiter on such complex trajectories? ’ Harry asked. ‘Why have them merge before they reach the centre?’

  Michael shook his head. ‘You haven’t grasped the subtleties of the design,’ he said seriously.

  ‘Evidently not,’ Harry said dryly.

  ‘Do you understand what happens when two singularities converge, combine? ’ He mimed, with his two fists, the singularities approaching each other, whirling around each other, finally merging. ‘The event horizons merge into a single horizon of greater net area ... Entropy, proportional to the area, increases. The singularities themselves, the flaws in space at the heart of the holes, fall in on each other; blueshifted radiation increases the effective mass until the final merger occurs on Planck timescales - the immense gravitational fields generated effectively deflate time. And the joint event horizon quivers like a soap bubble, generating radiation through quadrupolar effects.’

  Berg nodded slowly. ‘And what form does this - radiation - take?’

  He looked surprised by the question. ‘Gravitational, of course. Gravity waves.’

  She took a deep breath, felt her blood surge through her veins a little fast. Gravity waves.

  Michael explained further.

  These weren’t the dinky little ripples in spacetime, propagating at lightspeed, which had been studied by human astronomers for centuries ... When two massive singularities merged, the gravity waves were monstrous. Nonlinear distortions of spacetime itself.

  ‘And the radiation is directed,’ Michael said. ‘It pulses along the axis of the hole pair. By choosing precisely the placement and orientation of the holes at merger inside the carcass of the planet, you can direct gravity-wave pulses as you choose. You can sculpt the implosion of Jupiter by working its substance on a massive scale; it was the Friends’ intention, I believe, even to remove some of the mass of the planet before the final collapse. The precise size, angular momentum and charge of the final black hole are evidently important parameters for the success of—’

  But Berg was no longer listening. Then the earth-ship wasn’t just - just - a singularity-cannon platform. It was a gravity-wave gun.

  A human-built starbreaker.

  They could fight back.

  Michael looked up and gasped. The colour of the sky had changed, and cast grey shadows across his face.

  Berg looked up. A vast moon of flesh slid complacently towards the zenith, its gunmetal-grey surface pocked with eye sockets and weapon emplacements. Bloody scars a hundred yards wide disfigured the skin-hull. Berg searched for the Interface portal and made out another of the great elephant-ships emerging from the future. One of its limbs brushed the sky-blue wire framework of the portal, and a layer of flesh boiled away as the immense mass of the exotic matter raised tides in living tissue.

  Spline ...

  It had begun.

  Jasoft Parz, suspended in entoptic fluid, clung to t
he rubbery material of the Spline’s cornea and peered out at the past.

  Parz’s ship was climbing out of Jupiter’s gravity well now, on its way to its hyperspace jumpoff point to the inner planets. The wormhole Interface portal was receding; the portal looked like a bluish scar against the swollen cheek of Jupiter. Parz could see that a second Spline ship, the companion of his own, already loomed over the scrap of Earth-green that was the rebels’ craft.

  Parz sighed. ‘The rebel ship is elegant.’

  The Qax said, ‘It is a scrap of mud hurled into space by hyperactive apes.’

  ‘No. Look at it again, Qax. A camouflaging layer of earth built over a shell of Xeelee construction material ... They must have stolen a Xeelee flower, constructed this thing in some deep, hollowed-out cavern.’ He laughed. ‘And all under your watchful gaze.’

  ‘Under my predecessor’s gaze,’ the Qax said slowly. ‘According to the ship’s sensors the thing is constructed around a layer of singularities. A thousand of them, the total amounting to an asteroid-scale mass ...’

  Parz whistled. ‘That doesn’t sound possible. How—’

  ‘Obviously such masses could not be transported from space,’ the Qax said. ‘The rebels must have evolved some technique of assembling such materials from the substance of the planet.’

  Once humans had been able to engineer artifacts of exotic matter. Evidently not all of that technology had been lost, or confiscated by the Qax. Parz imagined wells of magma, shaped and compressed, imploded into a stream of singularities by immense forces ... He marvelled at the earth-craft. ‘It’s bold, audacious, ingenious.’

  ‘You sound proud.’

  Parz shrugged. ‘Why shouldn’t I be proud? In impossible circumstances, humans have achieved a remarkable feat. Even to come so far as these rebels have—’

  ‘Keep your sense of perspective,’ the Qax snapped. ‘This hardly represents a serious threat to the Occupation. For all the ingenuity of its construction we are faced by a single, ramshackle raft, barely capable of maintaining its structural integrity. And it was constructed furtively, like the burrow of a hunted animal. Where is the cause for pride in that?’

  ‘Perhaps the rebels see themselves as hunted animals,’ Parz said.

  The Qax hesitated. ‘Your admiration for these criminals is interesting,’ it said mildly.

  ‘Oh, you don’t need to worry,’ Parz said with vague self-disgust. ‘I talk a good rebellion. I always have. But when it comes to action, that’s a different matter.’

  ‘I know. I understand this feature of your personality. So did my predecessor.’

  ‘Am I as predictable as that?’

  ‘It is a factor which increases your usefulness, in our eyes,’ the Qax said.

  From behind the curved flank of the Spline, another ship appeared. This, Parz saw through the Spline’s lens, was one of the craft indigenous to the period: a squat, ungainly affair, gaudily painted, hovering before the eye of the Spline like some insect. The sensors showed there was a crowd of these barges, clustered around the Interface portal. So far none of them had interfered with the Spline - or attempted to interfere, rather.

  Parz said, ‘Aren’t you concerned about these local craft?’

  ‘They cannot harm us,’ the Qax said, sounding uninterested. ‘We can afford to take time here, to check through the Spline’s systems, before the cross-system hyperspace flight.’

  Parz smiled. ‘Qax, listening to you I can hear the voice of the commander of a twentieth-century atomic carrier disdaining the painted, dugout canoes of islanders, drifting out to meet him on the curve of some sea. Still, though, the most primitive weapon can kill ...

  ‘And I wonder why they don’t attack anyway.’

  He pressed his face to the cornea and glanced around the sky; now that he looked for them he saw how many of the strange local ships there were, and how diverse in design. The political structure in this period was chaotic, he recalled. Fragmented. Perhaps these vessels represented many different authorities. Governments of moons, of the inner planets, of Earth herself; as well as of the central, international agencies ... Perhaps no war council coalition existed here yet; perhaps there was no one to command an attack on this Spline.

  Still, Parz was irritated by the Qax’s complacency.

  ‘Aren’t you at least worried that these vessels might be raising a System-wide alert? Maybe the inner planets will be able to pack more of a punch against you,’ he said grimly. ‘And if they’re allowed to prepare ...’

  ‘Jasoft Parz,’ the Qax said with a trace of impatience, ‘your death-seeking fantasies are beginning to grate. I have monitored none of the dire warnings you seem to yearn for.’

  Parz frowned, absently scratching his cheek through the thick, clear plastic of his facemask. ‘The situation doesn’t make sense, actually, even given the political fragmentation. The Friends have been in this time period for a year. They’ve had plenty of time to warn the human natives of this era, to co-ordinate, assemble some sort of force to oppose you ... perhaps even to close the Interface portal.’

  ‘There has been no evidence of such co-ordination,’ the Qax said.

  ‘No, there hasn’t, has there? Is it possible the Friends haven’t warned the natives? - perhaps haven’t communicated with them at all, even?’ Parz could still make out the Friends’ craft against Jupiter, an island of green on a sea of pink. What were the rebels up to? The Friends must have had some project in mind when they made their desperate run to this period ... but evidently they had not felt the need to enlist the resources of the natives.

  Parz tried to imagine how a handful of rebels on a single improvised ship could hope to strike across fifteen centuries at an interstellar power.

  ‘It makes little difference,’ the Qax murmured, its disembodied voice like an insect buzzing somewhere behind Parz’s eyes. ‘The second Occupation craft is minutes away from the rebel craft, now; this absurd episode is nearing its climax.’

  ‘Michael Poole. Miriam.’

  Poole dragged his eyes away from the astonishing sky. Shira stood before them; Poole saw that the customary blank composure of her skeletal face was marred by a tightness of the mouth, a pink-white flaring of her small nostrils. Beyond her, the earth-craft was full of motion; Friends bearing slates and other pieces of equipment ran across the wiry grass, converging on the stones at the heart of the craft.

  Berg snapped, ‘Shira, those are Spline warships up there.’

  ‘We understand what is occurring, Miriam.’

  ‘Then what the hell are you going to do about it?’

  Shira ignored this and turned to Poole. ‘You must stay inside the tepee,’ she said. ‘The surface of the earth-craft is not safe now. The Xeelee construction material will shield you from—’

  Poole said, ‘I’m not going anywhere until you tell me what you’re going to do.’

  Harry, his image restored to brightness outside the hut, folded his arms and stuck his jaw out. ‘Me too,’ he said defiantly.

  Shira’s voice was fragile but steady enough. ‘We are not going to respond directly to the incursion of the Qax,’ she insisted. ‘There is no purpose—’

  Berg shouted, ‘You mean that after bringing them here you’re just going to let them walk in and do what they want?’

  Shira flinched at the other woman’s fury, but stood her ground. ‘You do not understand,’ she said, the strain still more evident in her voice. ‘The Project is paramount.’

  Harry tried to grab Poole’s arm; his fingers passed through cloth and flesh in a cloud of pixels. ‘Michael. Look at the Spline.’

  The first warship had crossed the zenith now and seemed to be receding from the earth-craft. Deep in its crater-like pores Poole saw the glint of blood and metal.

  The Spline’s partner, the second warship, was clear of the Interface. It was already the size of a large coin, and it grew visibly.

  The second ship seemed to be coming straight for them.

  ‘Only two,�
� Berg muttered.

  Poole glanced at her, startled; her face was screwed up tight around peering eyes. ‘What?’

  ‘No sign of any more coming through the portal. There’s already been time for a third to start appearing.’

  Poole shook his head, amazed at her ability to think her way through the looming threat from the sky. ‘Do you think something’s stopping them, at the other end?’

  Berg shook her head with a brief, dismissive jerk. ‘No way. Two is all they think they need.’

  Shira twisted her hands together anxiously. ‘Please,’ she said. ‘The tepee.’

  Poole ignored her. ‘What do you think they’re doing?’

  Berg, her fear gone now, or at least suppressed, tracked the silent motion of the Spline. ‘The first one’s leaving Jovian space.’

  Poole frowned. ‘Heading where? The inner Solar System?’

  ‘It’s logical,’ Berg said dryly. ‘That’s where Earth lies, fat and waiting.’

  ‘And the second?’

  ‘ ... Is coming down our damn throats.’

  Shira said, ‘You need not fear. When the Project comes to fruition these events will be ... translated into harmless shadows.’

  Poole and Berg, dropping their heads from the ugly movements in the sky, studied the Friend.

  ‘She’s crazy,’ Berg said.

  Shira leaned forward, her blue eyes pale and intense. ‘You must understand. The Project will correct all of this. The continuance of the Project is - must be - the top priority for all of us. Including you, our visitors.’

  ‘Even above defending ourselves - defending Earth - against a Spline attack?’ Poole asked. ‘Shira, this may be the best chance we’ll have of defeating the assault. And—’

  She didn’t seem to be hearing him. ‘The Project must be seen through,’ she said. ‘Accelerated, in fact.’ The girl looked from one to the other, searching their faces, pleading for understanding; Michael felt as if he could see the practised phrases rolling meaninglessly through her mind. ‘You will come with me now.’

  ‘What do you think?’ Poole said to Berg. ‘Will they force us? Do they have weapons?’