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

by Stephen Baxter

  Michael Poole turned to her, and nodded gently. The construction-material light shone out through his translucent face, making him look like a sculpture of light, she thought. He opened his mouth, as if to speak to her, but she couldn’t hear him; and now the light was all around him, engulfing him.

  ‘Come with me!’ she screamed.

  And now, suddenly, dramatically, the singularity was here. Its rim exploded outwards, all around her, and she fell, helplessly, into a pool of muddled starlight.

  She cringed into herself and clutched her hands to her chest; her worn arrow-head dug into her chest, a tiny mote of human pain.

  33

  The lifedome was plunged into darkness. The jungle sounds beneath Louise were subdued, as if night had fallen suddenly . . . or as if an eclipse had covered the Sun.

  The lifedome groaned, massively; it was like being trapped inside the chest of some huge, suffering beast. That was stress on the hull: the co-ordinate change, as the ship had crossed the singularity plane.

  We have entered a new cosmos, then. Is it over? Louise felt like an animal, helpless and naked beneath a storm-laden sky.

  Lieserl had spoken of how all of human history was funnelling through this single, ramshackle moment. If that was true, then perhaps, before she had time to draw more than a few breaths, her own life - and the long, bloody story of man - would be over.

  . . . And yet the sky beyond the dome wasn’t completely dark, Louise saw. There was a mottling of grey: elusive, almost invisible. When she stared up into that colourless gloom, it was like staring into the blood vessels she saw when she closed her own eyelids; she felt a disturbing sense of unreality, as if her body - and the Northern, and all its hapless crew - had been entombed, suddenly, within some gross extension of her own head.

  There was a rasp, as of a match being struck. Louise cried out.

  Mark’s face, dramatically underlit by a flickering flame, appeared out of the gloom. Lieserl laughed.

  ‘Lethe,’ Louise said, disgusted. ‘Even at a time like this, you can’t resist showing off, can you, Mark?’

  ‘Sorry,’ he said, grinning boyishly. ‘Well, the good news is we’re all still alive. And,’ more hesitantly, ‘I can’t detect any variation of the physical constants from our own Universe. It looks as if we may be able to survive here. For a time, at any rate . . .’

  Lieserl snorted. ‘Well, if this universe is so dazzlingly similar to our own - where are the stars?’

  Now the lifedome began to lighten, as Mark kicked in image enhancing routines. It was almost like a sunrise, Louise thought, except that in this case the spreading light did not emerge from any one of the lifedome’s ‘horizons’; it simply broke through the muddy darkness, right across the dome.

  In a few heartbeats, the image stabilized.

  There were stars here, Louise saw immediately. But these were giants - and not like the bloated near-corpse which Sol had become, but huge, vigorous, brilliant white bodies each of which looked as if it could have swallowed a hundred Sols side by side.

  The giants filled the sky, almost as if they were jostling each other. Several of them were close enough to show discs, smooth white patches of light.

  Nowhere in her own Universe, Louise realized, could one have seen a sight like this.

  Beside her, Lieserl sighed. ‘Uh-oh,’ she said.

  PART VI

  EVENT: NEW SOL

  34

  The light of New Sol gleamed from the pod’s clear hull, unremitting, blinding. Louise watched the faces of Mark, Spinner-of-Rope and Morrow as they peered out at the new cosmos. The pod turned slowly on its axis, and the brilliant young lamps of this new universe wheeled around them, bathing their profiles in intense white brilliance.

  For their new sun, the crew of the Northern had selected a particular VMO: a Very Massive Object, a star of a thousand Solar masses - a typical member of this alternate cosmos. This star drifted through the halo of a galaxy, outside the galaxy’s main disc. Huge shells of matter - emitted when the star was even younger - surrounded New Sol, expanding from it at close to the speed of light.

  The Great Northern itself hovered, a few miles from the pod. By the harsh, colourless light of New Sol Louise could see the bulky outline of the lifedome, with the sleek, dark shape of the Xeelee nightfighter still attached to the dome’s base - and there, still clearly visible, was the hull-scar left by the impact with the strand of cosmic string.

  The battered ship orbited the new sun as timidly as ice comets had once circled Sol itself - so widely that each ‘year’ here would last more than a million Earth years. The ship was far enough away that the VMO’s brilliance was diminished by distance to something like Sol’s. But even so, Louise thought, there was no possibility that the VMO could ever be mistaken for a modest G-type star like Sol. The VMO was only ten times the diameter of old Sol, so that from this immense distance the star’s bulk was reduced to a mere point of light - but its photosphere was a hundred times as hot as Sol. The VMO was a dazzling point, hanging in darkness; if she studied it too long the point of light left trails on her bruised retinae.

  Externally, the Northern’s lifedome looked much as it had throughout its long and unlikely career: the ship’s lights glowed defiantly against the glare of this new cosmos, and the forest was a splash of Earth-green, flourishing in the filtered light of New Sol. But inside, the Northern had become very different. In the year since its arrival through the Ring, the dome had been transformed into a workshop: a factory for the manufacture of exotic matter and drone scoop-ships.

  Morrow, beside Louise, was blinking into the light of New Sol. His cupped hand shaded his eyes, the shadows of his fingers sharp on his face. He was frowning and looked pale. He caught Louise’s glance. ‘Things are certainly different here,’ he said wryly.

  She smiled. ‘If we ever build a world here, it won’t have a sun in the sky. Instead, by day there will be this single point source, gleaming like some unending supernova. The shadows will be long and deep . . . and at night, the sky will shine. It’s going to seem very strange.’

  He glanced at her sharply. ‘Well, it will be strange for those of you who remember Earth, I guess,’ he said. ‘But, frankly, there aren’t so many of you around any more . . .’

  Now the pod’s rotation carried the new sun out of visibility, below the pod’s limited horizon. And - slowly, majestically - the lights of their new galaxy rose over their heads.

  This galaxy was a flat elliptical, but would have seemed a dwarf compared to the great galaxies on the other side of the Ring: with a mass of a billion suns, the star system was a mere hundredth the bulk of the Milky Way, or Andromeda, and not much larger than the old Magellanic Clouds, the minor companion galaxies to the Milky Way. And - since the average size of stars here was a hundred times greater than in the Milky Way - there were only ten million stars in this galaxy, compared to the Milky Way’s hundred billion . . . But every one of those stars was a brilliant white VMO, making this galaxy into a tapestry of piercingly bright points of light. It was like, Louise thought, surveying a field of ten million gems fixed to a bed of velvet.

  This universe was crowded with these bland, toy galaxies; they filled space in a random but uniform array, as far as could be seen in all directions. This cosmos was young - too young for the immense, slow, processes of time to have formed the great structures of galactic clusters, superclusters, walls and voids which would one day dominate space.

  Morrow stared up uneasily at the soaring form of the galaxy. Apparently unconsciously, he wrapped both hands across his stomach.

  ‘Morrow, are you okay?’

  ‘I’m fine,’ he told Louise, unconvincingly. ‘I guess I’m just a little susceptible to centrifugal force.’

  Louise patted his hands. ‘It’s probably Coriolis, actually - the sideways force. But you shouldn’t let the pod’s rotation bother you,’ she said. She thought it over. ‘In fact, you should welcome your motion sickness.’

  Morr
ow raised his shaven eyebrow ridges. ‘Really?’

  ‘It’s a sensation that tells you you’re here, Morrow. Embedded in this new universe . . .’

  The laws of physics were expressions of basic symmetries, Louise told him. And symmetries between frames of reference were among the most powerful symmetries there were.

  Morrow looked dubious. ‘What has this to do with space-sickness?’

  ‘Well, look: here’s a particular type of symmetry. The pod’s rotating, in the middle of a stationary universe. So you feel centrifugal and Coriolis forces - twisting forces. The forces are what is making you uncomfortable. But what about symmetry? Try a thought experiment. Imagine that the pod was stationary, in the middle of a rotating universe.’ She raised her hands to the galaxy wheeling above them. ‘How would you tell the difference? The stars would look the same, moving around the pod.’

  ‘And we’d feel the same spin forces?’

  ‘Yes, we would. You’d feel just as queasy, Morrow.’

  ‘But where would the forces come from?’

  She smiled. ‘That’s the point. They would come from the inertial drag of the rotating universe: a drag exerted by the huge river of stars and galaxies, flowing around you.

  ‘So you shouldn’t be worried by, or embarrassed by, your queasiness. That’s the feeling of your new universe, plucking at you with fingers of inertial drag.’

  He smiled weakly, and ran a palm over his bare, sweat-sprinkled scalp. ‘Well, thanks for the thought,’ he said. ‘But somehow it doesn’t make me feel a lot better.’

  Spinner-of-Rope and Mark were sitting in the two seats behind Louise and Morrow. Now Mark leaned forward. ‘Well, it should,’ he said. ‘The fact that general relativity is working here - as, in fact, are all our familiar laws as far as we can tell, to the limits of observation - is the reason we’re still alive, probably.’

  Spinner-of-Rope snorted; VMO light gleamed from the arrow-head pendant she still wore between her breasts. ‘Maybe so. But if this universe is so damn similar, I don’t see why it should be so different. If you see what I mean.’

  Mark spread his hands, and tilted his head back to look at the dwarf galaxy. ‘The only real difference, Spinner, is one of point of view. It’s all a question of when.’

  Spinner frowned. ‘What do you mean, “when”?’ Behind her spectacles Spinner’s small, round face seemed set, intent on the conversation, but Louise noticed how her hands tugged at each other endlessly, like small animals wriggling in her lap. Spinner-of-Rope had been left too long in that nightfighter pilot cage, Louise thought. Spinner had seen too much, too fast . . .

  Since she’d been retrieved from the cage Spinner had seemed healthy enough, and Mark assured Louise that she’d retained her basic sanity. Even her illusion of communicating with Michael Poole - an illusion she’d dropped as they came through the Ring - seemed to have had some, unfathomable, basis in reality, Mark said.

  Fine. But, Louise sensed, Spinner-of-Rope still wasn’t fully recovered from her ordeal. She still wasn’t whole. It would take time - decades, perhaps - for the post-traumatic stress to work its way out of her system. Well, Spinner-of-Rope would have the time she needed, Louise was determined.

  Mark said, ‘Spinner, this universe is just like ours - except that it’s around twenty billion years younger.

  ‘This is a baby cosmos. It emerged from its own Big Bang less than a billion years ago. And it’s smaller - spacetime hasn’t had the time to unravel as far as in our old Universe, so this cosmos is something of the order of a hundredth the size. And the stars—’

  ‘Yes?’

  ‘Spinner, these are the first stars ever to shine here. Not one of the stars we see out there is more than a million years old.’

  Out of the primordial nucleosynthesis of the singularity, here, had emerged clouds of hydrogen and helium, with little contamination by heavier elements. The new sky had been dark, illuminated only by the dying echo of the radiation which had emerged from the singularity. Then the gas clouds gathered into proto-galactic clumps, each with the mass of a billion Sols. Thermal instabilities had caused the proto-galaxies to collapse further, into knots with mass a hundred Suns or more.

  Soon, the first of these smooth-burning stars had guttered to life: brilliant monsters, some with the mass of a million Suns.

  Slowly, the sky had filled with light.

  ‘The way these stars were born is unique,’ Mark said, ‘because they are the first. There were no previous stars. So the proto-galaxies were a lot smoother - the gas clouds weren’t all churned up by the heat and gravity of earlier generations of stars. And the gas was free of heavy elements. Heavy elements act to keep young stars cooler, and to limit the size of the stars that form. That’s why these babies are so immense.

  ‘These are what we call Population III stars, Spinner. Or VMOs - “Very Massive Objects”.’

  ‘If they are so massive,’ Spinner said slowly, ‘then I guess they won’t last so long as stars like Sol.’

  Louise looked at her appreciatively. ‘That’s perceptive, Spinner. You’re right. The VMOs burn their hydrogen fuel quickly. Each of these is going to stay on its Main Sequence for no more than a few million years - two or three, at best. The Sun, on the other hand, should have survived for tens of billions of years, without the interference of the photino birds.’

  ‘What then?’ Spinner asked. ‘What do we do when New Sol goes out?’

  Morrow smiled. ‘Then, I guess, we move on: to another star, and another, and another . . . We have time here to work that out, I think, Spinner-of-Rope.’

  Now New Sol was rising again, over the lip of the pod. The four of them turned instinctively to the light, its flat whiteness smoothing the lines of age and fatigue in their faces.

  ‘In fact,’ Mark said, ‘the star we’ve chosen - New Sol - is already well past its middle age. It’s probably got no more than three-quarters of a million years of its life left.’

  Spinner frowned. ‘That seems stupid. Why not choose a young star, and move there while we can? It may be that when New Sol dies we won’t be able to move away.’

  ‘No,’ Mark said patiently. ‘Spinner, we need an older star.’

  The star called New Sol was nearing the end of the second phase of its existence. In the first, it had burned hydrogen into helium. Now, helium was fusing in turn, and a rain of more complex elements had formed a new, inner core: principally oxygen, but also neon, silicon, carbon, magnesium and others.

  And later, in the third phase of its life, when the oxygen started to burn, the star would die . . . although how was far from certain.

  ‘Terrific,’ Spinner said. ‘And we die with it.’

  ‘No,’ Mark said seriously. ‘Spinner-of-Rope, we die without it. Don’t you get it? New Sol is full of oxygen . . .’

  Morrow was pointing, excitedly. ‘Look. Look. There’s the wormhole . . . I think it’s almost time.’

  Louise turned in her seat.

  Now a new form emerged over the rotating pod’s horizon: the familiar shape of a wormhole Interface. This Interface was only a hundred yards across - far smaller than the mile-wide monster the Northern had hauled across a different spacetime - but, like its grander cousins of the past, it shared the classic tetrahedral frame, the shining electric blue colour of its exotic matter struts, and the autumn-gold glimmering of its faces. A dozen drone scoop-ships prowled around the Interface, patient, waiting.

  Louise felt a prickle of tears in her eyes; she brushed them away impatiently. Already, she thought, we are building things here. Already, we are engineering this universe.

  Mark said to Spinner, ‘If there were planets here we could land and try to terraform one. But there are no planets for us to land on. Anywhere. This is a very young universe. There are no more than traces of heavy elements here, anywhere, outside the interior of the protostars. There are no moons, no comets, no asteroids . . . We have no raw materials to build with, save the hulk of the Northern - save what we bro
ught here ourselves. We can’t even renew our atmosphere.’

  Morrow nodded. ‘So,’ he said, ‘we’re mining the star.’

  The second terminus of this wormhole had been dropped into the carcass of New Sol. Lieserl had accompanied the Interface - just as once she had travelled into the heart of Sol itself. Soon, enriched gases from the heart of the new star would pour into space - here, far from the heat of New Sol, accessible.

  The scoop-ships had mouths constructed of electromagnetic fields which could gather in the star-dust across volumes of millions of cubic miles. When the wormhole started to operate, the scoops would sift out the few grains of precious heavy elements.

  ‘The first priority is atmospheric gases,’ Mark said. ‘We lost a lot of our recyclable reserve during the string impact. Another blow-out like that and we’d be finished.’

  ‘Are all the gases we need there, inside the star?’

  ‘Well, there’s plenty of oxygen, Spinner,’ Louise said. ‘But that’s not enough. An all-oxygen atmosphere isn’t particularly stable - it’s too inflammable. We need a neutral buffer gas, to contribute to the hundreds of millibars of pressure we need to stay alive.’

  ‘Like nitrogen,’ Spinner said.

  ‘Yes. But there isn’t much nitrogen in New Sol. We should be able to use neon, though . . .’

  ‘We can replace our other stores. Use the oxygen to make water and food.’

  ‘We can do more than that, Spinner-of-Rope,’ Mark said. ‘In the longer term we can extract heavier elements: magnesium, silicon, carbon - maybe even iron. They are only present in traces in New Sol, but they’re there. We can build a fleet of Northerns, if we’re patient enough. Why, we can even make rocks.’

  Spinner looked out at New Sol, and the point light glittered in her eyes, making her look very young, Louise thought. Spinner said, ‘It’s chilling to think that - except maybe for the Xeelee - we’re alone here, in this universe. Stars like this once burned in our Universe - but they were all extinguished, destroyed, long before humans became conscious.