Xeelee: Vengeance

by Stephen Baxter

  ‘But you made sure I was there too, Harry. Down on Mars myself. And it was nothing to do with my being some symbol of resistance, was it? I was a big fat target. You knew the Xeelee was somehow drawn to me – that all this is somehow about me. And you used that. The camouflage, the gamers – all of that was a distraction. I was the real lure. All the Xeelee was likely to care about. You used me, without my consent or knowledge—’

  ‘So what are you accusing me of – manipulating you to save the Earth?’

  ‘You didn’t tell me. You didn’t give me a chance to do it voluntarily.’

  ‘So is that a crime? Is that unethical? How do you think it made me feel? I did what I had to do.’ Harry’s expression hardened; his eyes narrowed. ‘You always did lack ambition, Michael. But usually you show vision, at least – as with your scheme for the Carnot, here. Yes, that was the plan, the hope anyhow. Yes, I used you, if that’s what’s bothering you. And, frankly, I couldn’t take the chance that you’d refuse.’

  ‘So you never trusted me.’

  ‘What does that matter? It worked. The Xeelee was drawn to Mars, and we’ve got that much more time to figure out how to stop it before it gets to Earth.

  ‘And, listen, Michael – you can rail at me all you like, if you think I betrayed you. But if you’re the genius everybody wants to think you are, shouldn’t you have thought of it yourself? Huh? The lure scheme? You know, whatever everybody else thinks of you, you don’t impress me. And every time you challenge me you remind me of that. You and your end-of-time Ghost and your Sigil of Free Humanity – that’s nothing but tales for children, Michael. Like comic-book stories about the Mariner from Mars. And you, you are still a child—’

  Abruptly the security bubble broke down. Some kind of override had been applied. Poole heard a babble of voices, that dreadful architectural groaning from the stressed building around him – and a message from his mother, clamouring in his ear.

  Things had moved on.

  The tetrahedral cage of planetbuster energy was still in place, still hammering at Mars. Still delivering a fresh Chicxulub every hour. But the Xeelee itself had broken away. Moved away from Mars, and had swum off into interplanetary space. Surely it had only one destination – Earth. And given the precedent of the Martian Cage, its intention there seemed clear.

  Poole turned and ran, seeking a ride to a flitter to orbit. Gallia: that was his only thought. He had to get to Gallia Three, and Miriam, and Highsmith Marsden. That was surely where the only hope for resistance lay now.

  Behind him he heard Harry call. ‘You’re nothing but a child to me, and always will be. I’m your father. Your father!’

  SIX

  With the Xeelee there has never been a possibility of negotiation, diplomacy, compromise. None. In fact there has been no contact at all – other than the brutal collision of conflict. The Xeelee ignore us until we do something that disturbs them – and then they stomp on us hard, striking with devastating force until we are subdued. To them we are vermin. Well, the vermin are fighting back.

  Commissary Dolo, ad 23479

  54

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  Not long after the Xeelee’s arrival in the Solar System, under Highsmith Marsden’s orders the Gallia Three habitat had abandoned its ancient cycler orbit. No longer did it patiently cruise between inner and outer planets; now Gallia was suspended forever in Jupiter’s orbit, at the fifth Lagrangian point, hidden in a diffuse cloud of asteroids at this place of stable gravitational equilibrium.

  Hidden here too was a cluster of GUTships of various classes: all of them Poole Industries vessels, though many were owned by other parties. They were all that Poole, with some covert help from Harry, had been able to commandeer in the eight months since the Xeelee had caged Mars. A rough and ready war fleet.

  And here at Gallia, with only weeks left before the Xeelee was expected to arrive at Earth, Highsmith Marsden had his weapon, at last.

  In great secrecy, Poole learned, prototypes had been manufactured using the huge energy flows of the Io flux tube, shipped cautiously to Gallia in armoured GUTships, and were now stored in a detached laboratory outside the Gallia habitat itself. This lab unit was a cylinder crammed with instruments, and fed with energy by two interplanetary-capable GUTengines. Nobody built of flesh and blood was allowed inside. Only Virtual projections.

  So now Poole, with Highsmith Marsden, Miriam Berg, Poole’s mother Muriel and Nicola Emry, drifted inside a space dimly lit, full of shadows, and so crowded that Poole was distracted by sharp flashes of pain as he bumped up against surfaces, and consistency-violation pixel showers were constant glimmers in the corner of his eye.

  Nicola Emry grinned. ‘Just as well we’re all such good friends.’

  Miriam said bluntly, ‘You want to try working in these conditions.’

  ‘Play nicely, children,’ Muriel said softly. ‘Just remember it’s like this for me all the time—’

  ‘Then you should have stayed away,’ Poole said bluntly.

  Miriam glared at him, evidently disapproving.

  Muriel herself looked saddened, Poole thought with a stab of regret. But she understood, he thought. She tended only to show up in his life when she had some new bit of spooky, disturbing information about his clinging past to force on him. He ought to resent that, the lost generations of Pooles, rather than her, he thought now.

  He tried to focus on the here and now.

  Evidently Highsmith Marsden felt the same. ‘All of you shut up,’ he said. ‘And pay attention to a miracle.’

  Nicola laughed out loud.

  Then, in respectful silence, they took turns at the eyepiece of a small optical microscope. Poole thought that the simplicity of the equipment, in this setting, actually enhanced the significance of the achievement.

  When it was his turn, Poole saw only a speck of light, glowing brilliantly.

  Marsden seemed irritated at their subdued reaction. ‘Are you impressed? No? You should be. That, my unsatisfactory audience, is a magnetic monopole. Manufactured using the Io flux tube energies, and held in place with a strong magnetic cage.’

  Miriam was nodding. ‘And with this we have at last a fighting chance against the Xeelee.’

  Her mood was not like Marsden’s, Poole saw. Marsden was the mannered, academic eccentric. Whereas Miriam was – eager. Poole had known Miriam a long time. She’d changed, her attitude harder. Bleaker. She looked older than her age, AS treatments notwithstanding – older than Poole, though he had been born a few years earlier. And, ever since the lethal incident on Io, this had been a personal fight, for her. They were all different people, he supposed. Not who they might have become if not for the Xeelee.

  ‘As to the design of weapons—’ Marsden moved back, clapped his hands, and now the awkward space was further crowded by a Virtual display that hung in the air between them: the Xeelee, the now infamous sycamore seed craft. ‘Naturally we’ve been studying the Xeelee closely since it first burst out of the wormhole into the Solar System, and especially since its hostile intent became evident. And through that deeper scrutiny we have learned much. Particularly concerning the way it moves.’

  The image of the Xeelee shimmered and flickered, and Poole realised he was seeing a composite of many records, crudely spliced together. But he could see how, out of those swept-back, lobe-like wing stubs, further extensions emerged, or unrolled perhaps, flickering into existence, morphing: elusive geometries.

  ‘The imaging is uncertain,’ Marsden said now. ‘Of course we haven’t always known what we are observing, so that is always a challenge as to how to observe. The best clues came from gravity-wave measurements, in fact, which are a particularly strong signal from the Xeelee.

  ‘But the wing extensions you see here – and we don’t believe we’ve seen the full extent, we think the Xeelee’s motions have been relatively cautious – are clearly the secret of
its propulsion method. They are not material, not mass or energy. They are discontinuities in spacetime . . .’ He paused, looking around at them, showing comparatively mild irritation – mild for him – at the blankness of their faces. ‘Well?’

  Nicola whispered to Poole, ‘He’s like a tutor I had in the remand centre at Aristarchus.’

  He glanced at her. ‘You never told me about that.’

  ‘One of my mother’s ideas to improve my character.’

  ‘That worked well.’

  ‘You just have to let him run down, until he tells you what you need to hear.’

  Miriam was glaring at them; Poole shut up.

  ‘The vacuum can take many energy states,’ Marsden said at last. ‘It is just as water can be found as a solid – ice – or a liquid, or a vapour – as steam – or a plasma. And just as water releases energy, latent heat, when it collapses between states – from steam to liquid water, or liquid to ice – so the vacuum releases energy as it collapses from one state to another. These pulses of phase-change energy had a key role in the shaping of the universe, in the very early moments after the singularity itself.

  ‘But – when water freezes, ice rarely forms uniformly and regularly. Which is why, in a cube of ice you would drop in your drink, you will often find defects: bubbles and lines and planes of fracture. And so, as it congealed, spacetime too has been left full of flaws. Now, since spacetime has extensions in three space dimensions, then just like an ice cube it contains flaws in lower dimensions: two, one, zero.’

  Miriam said, ‘The defects most commonly experienced in nature are one-dimensional. Enormous threads—’

  ‘Cosmic strings,’ Poole said. ‘My astrophysics is coming back to me.’

  ‘Right. Stretched out across the cosmos, endlessly on the move, propagating at near lightspeed. And essentially tubes of high energy – a relic of the state of the early universe – just as a linear crack in an ice cube will be full of liquid water. A remnant of the previous state, you see. Cosmic strings are massive enough to distort spacetime itself. To bend space around them.’

  Muriel said with a trace of impatience, ‘So that’s one-dimensional flaws. And in two dimensions – some kind of sheet?’

  ‘Indeed,’ Marsden said. ‘An extensive, planar crack in spacetime. Domain walls, these ruptures are called. Again their tendency, once formed, would be to propagate away at lightspeed.’

  ‘Ah,’ Nicola said. ‘I get it.’ With a delicate Virtual finger – delicate for her anyhow, Poole thought – she poked at the profile of the flickering extension of the Xeelee wing. ‘We know the main hull and these lobes are made, like the Cache, of what we’ve called hull plate. Right? Which is a marvel in itself. But this wing, I’m guessing, is your planar spacetime defect.’

  Miriam said, ‘As Highsmith pointed out such a defect will propagate in space. Imagine a shock wave in spacetime itself – like an ocean wave on the point of breaking. A nonlinearity. And if you could harness that motion . . . A discontinuity drive, we are calling it. It’s a little like our wormhole design strategy, Michael. The Xeelee essentially rides instabilities.’

  Watching the simulation, entranced, Poole saw how the spacetime-defect wings were not static structures; they folded, twisted, changed.

  Miriam described this as a ‘geometric phase’ motion. ‘The Xeelee swims by changing the shape of these defects and pushing at spacetime itself. It’s rather like the way some bacteria swim through water . . . To a Xeelee sycamore seed ship, spacetime is as dense as water is to a bacterium. Thick as treacle.’

  Marsden said, ‘All this, if I may speculate, may be another relic of the very early universe. In an age even before the time of the quagma phantoms – even before the GUT era, when gravity was still combined into the single superforce – spacetime itself was a young, frangible thing, twisted and torn by the relic energies of the singularity. And it was full of defects. Perhaps, if life in that chaos was somehow possible, it might have survived in subsequent epochs, even achieved symbioses with other kinds of life. Just as we appear to see here.’

  Poole said, ‘Tactically, though. This discontinuity drive of yours would make a ship highly manoeuvrable. We’ve studied military technology of the past: fighter planes of the Anthropocene wars, for instance. As soon as they could, they made their planes smart, and deliberately unstable. Because if you can control that instability, with fast enough reflexes, you can slip quickly from one mode to another – faster than between stable states. Manoeuvrability was the key to winning a dogfight.’

  Marsden glared at him. ‘“Dogfight.” Miraculous science expressed in language little more sophisticated than a chimpanzee’s pant-hoot.’

  Nicola stared at Marsden. ‘Did he say “pant-hoot”? I love this guy. I want to have his babies.’

  Miriam suppressed a laugh, coughing. ‘But,’ she said, ‘that is a valid perception in the circumstances, Highsmith. A pilot’s perception, and that’s the point of all this. Yes, a warship driven by spacetime discontinuities would be highly manoeuvrable.’

  Muriel said thoughtfully, ‘But you say this drive, miraculous as it is, is restricted to lightspeed, or less.’

  ‘That’s correct,’ Miriam said. ‘The Xeelee must surely have a more capable interstellar drive. Some kind of hyperdrive, we think. I mean, a drive capable of transcending the normal dimensions of space and time altogether. But if it does, we haven’t seen it in action. The Xeelee, after all, arrived in this System through the Poole wormhole.’

  Muriel said now, ‘Our descendants will have hyperdrive capability. At least, so the family archives hint. We will fight a faster-than-light war with the Xeelee at the centre of the Galaxy.’

  Marsden eyed her. ‘Really? Now that would be interesting. Because FTL ships are also time machines, potentially. A war of time paradoxes . . .’

  Muriel, rather awkwardly, turned to Poole. ‘Actually, that’s something we need to talk about. Time travel. History-tinkering. Paradoxes.’

  Poole’s face felt hot. He stared down once more at the shining dot in the microscope’s field of view. ‘Getting back to the point – defects in spacetime – this, I’m guessing, is a zero-dimensional defect. A point.’

  ‘A magnetic monopole,’ Marsden said, with allowable pride, Poole thought. ‘Produced naturally in the early universe when phase-change GUT energy powered a surge of expansion – we call it inflation. Space swarmed with monopoles, like bubbles of water locked in ice, all merrily decaying away. Now we are using GUT energy again, as harnessed by Poole Industries engine pods, to create this new batch.’

  ‘And weaponised,’ Miriam said with that grim tone. ‘Built to a uniform size and mass. A monopole is a few hundred nanometres long, so it’s visible through this scope, but it has the mass of a trillion protons – about the mass of a DNA molecule. I like that, don’t you? A good mass for a human-made bullet. And soon we’ll be churning these things out like an Anthropocene war-industry armaments factory.’

  Nicola glared down at the microscope, as if she could make out the captive monopole through sheer will power. ‘Ah, I get it. Bullets. Because the way you puncture one spacetime defect—’

  ‘Is by firing another spacetime defect at it,’ Highsmith Marsden said.

  The meeting broke up with a kind of grim satisfaction. Nicola in particular fizzed with energy, and immediately started work on preparing the new technology for tactical use. Poole made sure she had the support she needed.

  But, he knew already from earlier briefings, though the monopole weapon was indeed a miracle, it wasn’t likely to be enough. While Marsden had developed useful hypotheses about the structure and function of the Xeelee’s sycamore seed vessel, the planetbuster technology behind the Cages, though heavily studied at Mars, remained a mystery. Unfathomable and, for now, unbreakable. So Poole believed that, when the Xeelee came to Earth, to win a battle they dare not lose, they needed mor
e. A Plan B.

  Right now he had no Plan B. Only vague notions of more or less outrageous implausibility, impracticality and unacceptability.

  As he worked on these schemes, he was summoned by the Virtual ghost of his mother.

  55

  When he went to see her, in the small bamboo hut she’d been assigned inside Gallia as a polite nod to her Virtual privacy, Muriel sweetened the pill with new reports from Earth and the inner System.

  She had always had privileged information. Poole suspected, in fact, that behind her lay a kind of shadow Virtual society, a network of artificial sentiences and simulated humans like herself – subtly disconnected from corporeal humanity, lacking true sensation, true joy, true pain, and yet deeply tied to their flesh-and-blood progenitors by the simple fact that if human civilisation collapsed, so would the power systems and information stores that such minds inhabited in the first place.

  Anyhow, now Muriel was able to show Poole a stream of reports from Mars, pinned within its deadly Cage.

  Eight months on, much of the atmosphere had been stripped off, all the water was broken up and gone, and most life was extinct – Jack Grantt and his colleagues had done their best to salvage something at least of the world-spanning Lattice – so that there was nothing left but geology, and even that was dissolving as swathes of the crust melted, exposing the liquid mantle beneath the skin. The great Tharsis volcanoes, destabilised, were all erupting now, blanketing the planet with a layer of dust and ash that obscured the surface, which itself was fracturing along billion-year-old fault lines. The Marineris valley system brimmed with magma, a shining river a thousand kilometres long. The northern hemisphere, that ancient sea bed, seemed to be shattering into islands of rock isolated by a new rising sea of lava. Poole almost felt the planet’s chthonic agony, as if in sympathy.