Proxima

by Stephen Baxter

  The family walked to the lake’s latest location, with Beth skipping ahead, and Mardina and Yuri side by side.

  The ground in this country, away from the lake and the water courses, was as arid as they had ever experienced it. In fact, Yuri suspected the landscape was becoming drier, hotter, the further south they travelled. Which made sense; the further south you went and the closer to the substellar point you reached, the further Proxima rose in the sky, and the more heat it delivered. Yuri still had the map Lemmy had compiled from the colonists’ remembrances of the shuttle flight, before they’d all killed each other, and that showed concentric bands of climate and vegetation types around the substellar. If they walked far enough, Yuri supposed, they would in the end reach true lifeless desert, surrounding the substellar point itself, which the ColU predicted would be the site of a permanent storm system. Even before that, maybe there would come a point where the ground was no longer habitable for them at all. But they were following the builders, who had evidently been going through this process for uncounted millennia, and Yuri and Mardina had decided to trust them – well, having followed the jilla this far, they had no choice.

  They came to the lake shore, a fringe of muddy ground with banks of new stems growing vigorously. The stems seemed to be self-seeding, but the colonists had observed the builders practising what looked like simple agriculture to help the stems along, planting shoots, irrigating the mud with crude drainage ditches. The water itself was still turbulent and turbid, not yet having settled into its new bowl. Around the shore of the lake Yuri could see builders working, setting up what looked like a nursery area with the outlines of domed shelters rising up from the debris – and already assembling basic middens, in preparation presumably for the next move of the jilla.

  But there was another area where builders, adults and children, had been herded in a huddle, surrounded by others that spun and whirled around them. One by one the prisoners were taken out to an area where more builders pinned them down and, brutally, crudely, disarticulated them, taking away their constituent stems to one of the new midden heaps. It looked like a prison camp crossed with an open-air operating theatre – or, perhaps, like some appallingly brutal schoolyard game being played out by stick puppets. The sound of the continuing murders was an eerie rustling, a clatter of sticks, the scrape of sharpened stone on stem bark.

  Yuri and Mardina gently guided Beth away from the scene. They had seen this many times before: it was the aftermath of a builder invasion, of conquest. There had been another community of builders here, living in the formerly dry lake bed, happily feeding off the local springs and stems – before the jilla folk arrived, brutally evicted them, flooded their homeland, and massacred any survivors.

  Beth hadn’t yet worked this out. Now, luckily, she spotted the nursery and ran that way to see.

  ‘The same every time,’ Mardina said, looking back at the slaughter yard. ‘And I used to think the builders were cute . . .’

  Yuri said, ‘They’re little wooden Nazis. Some day we’re going to have to explain all this to Beth, you know.’

  ‘Genocide in Toyland. There’s never going to be a good day to talk about that. Maybe you could tell her about your Heroic Generation at the same time. Give her some context. It’s not just builders that behave this way.’

  ‘For the thousandth time, it wasn’t my . . .’

  But of course she was only goading him, for the thousandth time. She asked, ‘What did the ColU want to talk to me about, by the way? Seemed very intense.’

  ‘Oh, one of its theories. Life on Per Ardua. It seems to have got a pretty good family tree for this world now. Lots of bragging about genetic comparisons and stuff. He’s identified major revolutions in the story of life here.’

  ‘What revolutions?’

  Yuri thought back. ‘Photosynthesis, I mean a fancy advanced kind that produced oxygen as a waste product. Then complex cells, with nuclei. Then plant and animal life. The ColU got worked up about the dates it’s established for these events. Meant nothing much to me.’

  ‘What dates?’

  He concentrated. ‘Photosynthesis two point seven billion years ago. The complex cells two billion years ago. And the animals – umm, five hundred and forty-two million years ago, I think.’

  Mardina stared at him.

  Some distance away, at the fringe of the trodden mud around the new lake, Beth had found something worth shouting about. She jumped up and down, waving. ‘Mom! Dad! Come see!’

  Mardina called, ‘OK, sweetie.’ They began to walk over. ‘Yuri – are you sure about those dates?’

  He felt uncertain, now she pressed him. ‘Well, I think so.’

  ‘It’s just – I’m no expert, but I took terraforming modules during my ISF training, and we studied the history of Earth life, the key transitions. Yuri, the dates for the similar events on Earth are: two point seven billion years, two billion years, and—’

  He guessed, ‘Five hundred and forty-two million?’

  ‘Yeah. I mean the last particularly is pretty precise, from the fossil record on Earth.’

  ‘Mom! Dad! Come see, before it all gets trampled!’

  Mardina said, ‘Life on two worlds separated by light years having a common sugar base – well, you can wave your hands about panspermia to justify that. But such a precise coordination of the key dates of all those improbable events?’

  ‘What does it mean?’

  ‘Damned if I know.’

  ‘Mom! Dad!’ Beth, quite agitated, was almost screaming now.

  And when Yuri and Mardina finally got there, at the edge of the pond’s muddy fringe, they could see immediately why.

  Beth had found a human footprint.

  CHAPTER 41

  The invitation from Earthshine reached Stef at her workstation in the UN kernel lab on the moon.

  In a short, low-res holographic message – a cube showing his well-groomed head, his smiling middle-aged-politician-type face – the Core AI requested that she come visit him on Earth, at what he called his ‘node’ in Paris. He said he had a matter to discuss of global importance, but specifically of interest to ‘you and your sister’. There was also an avowal, in legal wording, that the AI would make no attempt to access the growing knowledge base on kernel physics during his meeting with the sisters. Without that avowal Stef supposed the message would never have been allowed through the various layers of security that surrounded her, here at Verne.

  A similar message, an attachment noted, had been sent to Penny on Mercury.

  Stef shut down the hologram with a curt acknowledgement of receipt, and spent a full dome-day thinking it over. That was her way when faced with dilemmas she found difficult or personally unpleasant, a way she’d developed of managing her own instincts over nearly thirty-six years of life. Let the news work its way through her conscious and subconscious mind, before formulating a decision. She even slept on it.

  For one thing there was the sheer time she would need to take out of her own programme. Right now Stef was in a work jag that she was reluctant to climb out of. Well, she was always in a work jag. Seven years on from the Hatch’s first opening and the Penny incident – as she thought of it – explorations of the Hatch and investigations of its physical properties were shedding some light on the complementary studies of the kernels that had been going on for decades now. It was a slow, painstaking process, and it was full of gaps. Stef had the feeling she had been handed the two ends of a long chain of discovery, and she had a way to go before she worked her way from either end in towards the centre. But it was absorbing – there was more than a lifetime’s work here for her and her colleagues, she was sure. And that was a pleasing thought, since it pushed the need to make any drastic decisions about her own future off beyond the horizon.

  Decisions such as about her relationship with her sister.

  There was another reason for her to be wary about Earthshine’s note. She was actually working now with Penny. Her sister, who was on Mercury
, was running direct experimentation on the Hatch emplacement, trying to detect emissions of various exotic high-energy particles. Unlike some siblings, indeed some twins, the sisters worked well together, as a long string of academic publications to their individual and joint credit from the beginning of their careers proved. In this particular project at this particular time Penny was the experimentalist, Stef the theoretician, but on other projects in the past, the record showed, it had often been the other way around. They were flexible that way, with close but complementary skill sets.

  It was all fine and dandy, a family relationship to be admired and envied, and something that both their father and mother would have been proud of. It was just that Stef had no memory of any of this before the damn Hatch on Mercury had opened.

  The news of the discovery had quickly leaked, and the Hatch had been a sensation for about twenty-four hours. It was after all evidence of alien intelligence in the solar system. But a Hatch leading nowhere had since been largely forgotten, or dismissed as a hoax, though it still trailed conspiracy theories like a comet tail.

  But Stef was left with a massive rewiring of her own past.

  Before the Hatch, she had been an only child. After it, suddenly she had a twin. Not only that, she suddenly had a whole different lifetime behind her, intertwined with that of her twin. Papers that had been to her sole accreditation, for instance, were now under joint authorship with her sister. She’d read some of them; they were much as she remembered writing them, but not quite – not significantly better or worse academically – and there were others, reflecting bits of work she couldn’t remember, that she’d never generated herself at all.

  Only Stef remembered her solitary past before. Nobody else. Everybody in her life, including colleagues she’d known since her graduate-student days, thought of her now as half of a pair, not Stef alone. Not even King and Trant, who had been there at the moment of transition, remembered the old timeline.

  Not even Penny remembered it. As far as Penny was concerned, their joint careers had just carried on, after a hiccup as Stef had tried to absorb what had happened at the Hatch. To Penny, Stef was a sister who had suddenly developed a kind of selective amnesia.

  And maybe that was what it was. Some kind of mild craziness, perhaps triggered by some bizarro radiation field leaking from the alien artefact into which she’d climbed. That was the simplest explanation, after all, that her own perception, her memory, was somehow faulty. Though she’d looked hard, Stef hadn’t found a single shred of evidence to contradict the reality of it. The alternative, that history had somehow been changed around her, that the fault lay in the external universe rather than in her own small head, seemed an absurdly over-elaborate explanation by comparison.

  She didn’t believe that, however. She knew herself, she knew her past, her life. And this past wasn’t hers.

  She’d learned not to talk about this, not to anybody – not after the first few minutes of utter bafflement, up there on Mercury, in her pressure suit, in the Hatch, facing a sister she’d never known existed, and everybody had stared at her in dismay as she babbled out her confusion. After all she’d rather be working on kernel super-physics than spend the rest of her life on medication and therapy intended to rid her of ‘delusions’. She wouldn’t even talk to Penny about it, despite her sister’s tentative attempts to break through the barrier. Stef had been very happy to see Penny posted to a different planet, happy to just get on with her work; at least the work had stayed a constant comfort.

  But now here was this summons from Earthshine, evidently intended to bring the two sisters together.

  It seemed to Stef that despite much study and commentary, even while everybody acknowledged their power, most experts were unsure what the real agenda of the Core AIs might be. The three antique minds, a legacy of a difficult past, had no formal role in human society, no legal status – no rights, in a sense. But everybody knew that human agencies, from the UN and nation states on downwards, had to deal with them. Their power was recognised the way you would acknowledge the power of a natural phenomenon, a hurricane; you couldn’t ignore them, but they were outside the human world. And unlike hurricanes, the Core AIs could think and communicate.

  Now Earthshine had chosen to communicate with Stef and her sister. Why? That depended, Stef supposed, on Earthshine’s own agenda. Maybe Earthshine had some kind of insight to share. But did she want her personal tangle of a life to be unpicked by such a monster?

  On a personal level she was repelled. But on an intellectual level she was intrigued.

  She acknowledged the note, logged the trip in her personal schedule, and with relief went back to work.

  CHAPTER 42

  Stef Kalinski dropped from the moon’s orbit to Earth, following the usual leisurely three-day unpowered trajectory. At Earth orbit she had to wait a day before she was transferred to an orbit-to-ground shuttle, like a snub-nosed plane with black heat tiles and white insulation, its cabin crowded with passengers and luggage.

  The little craft glided down through the air with looping, sweeping curves.

  On its final track the shuttle crossed the eastern coast of South America, coming down towards a strip of flat coastal savannah. The land glimmered with standing water, flooded by the rising ocean despite crumbling levees that still lined the coast. This was Kourou, Guiana, the old European space agency launch centre, now converted to a surface-to-orbit transit station. Further inland Stef saw bare ground, scrub, some of it plastered with solar-collector arrays like a coat of silver paint. This site was only a few hundred kilometres north of the mouth of the Amazon. Now there was no forest, and the river was reduced to a trickle through a semi-desert.

  Only an hour after landing at Kourou Stef was being bundled into a small aircraft for her hop across the Atlantic. Like the shuttle the plane was crowded, fully loaded before it was allowed to take off; these days transport was always communal and always crowded, planes and shuttles and trains and buses, minimal energy usage the key goal.

  The plane, powered by turbos driven by a compact microfusion engine, leapt easily into the air. The sky beyond the small, thick windows turned a deep blue; the trajectory was a suborbital hop, and they crossed the Atlantic high and fast, heading north-east towards western Europe, Portugal and Spain.

  As the plane dipped back into the atmosphere over the Iberian coast, Stef wished she knew enough geography to recognise how much of this coastline had been changed by the risen sea. Near the shore she saw vapour feathers gleaming white, artificial cloud created by spray turbines standing out to sea and deflecting a little more sunlight from the overheated Earth. The ocean itself was green-blue, thick with plankton stimulated to grow and draw down carbon from the air.

  The plane banked and headed north, streaking at high speed through the air. Southern Spain, long abandoned to desert, was chrome-plated with solar-cell farms, and studded with vast silvered bubbles, lodes of frozen-out carbon dioxide. Once across the Pyrenees they left behind the mid-latitude desertification zone and the ground gradually became greener. But even in central France Stef glimpsed great old cities abandoned or at least depopulated, the conurbations’ brown stains pierced by green as they fragmented back into the villages from which they had formed. Over northern France the plane swept west, circled, and then descended into an easterly headwind. Stef saw something of the Seine, more abandoned towns on a glistening floodplain. Away from the river olives grew in neat rows on dusty ground, a sight you would once have seen in southern Spain, an agriculture suited to the new age.

  At Paris, the big old airports were no longer in use. Instead, with a stab of sharp deceleration, they were brought down at a small airport in a suburb called Bagneux, just south of central Paris itself, a clutter of ugly twentieth-century buildings cleared in great stripes to make room for the runways. There was another brisk transfer made mostly in silence; there was no documentation, but every passenger’s identity, security background and infective status were seamlessly checke
d with non-invasive DNA scans.

  Soon Stef was through the process, and found herself and her minimal luggage alone in a small driverless electric car that whisked her north towards the city centre. She’d not been to Paris before, and the cramped streets swept by at bewildering speed. Somewhere the Eiffel Tower still stood proud, but around her she saw only walls of ancient sandstone stained by floodwater. Although this was still the political capital of the country there were few people around. Wealthy Parisians had long ago decanted to the cooler climes of southern England – Angleterre as it was known now – and the poor, presumably, had died out or drifted away.

  She glimpsed the Île de la Cité, standing in the turbid waters of the Seine, where the roofs of Notre Dame were plastered with solar panels. A huge banyan tree sprawled before the cathedral, rooted in the flooded ruins of surrounding buildings.

  At last the car brought her to the Champs-Élysées, an avenue even a first-time visitor like Stef could not fail to recognise. There was a fair density of traffic here, and pedestrians hurrying beneath sun-shade awnings. The car stopped outside a high, elaborate doorway, where a man stood in the shade, beside a slim woman in the uniform of the ISF. The man, of course, was Earthshine. And the woman was Penny Kalinski, Stef’s impossible sister.

  Earthshine, who cast a convincing shadow when he stepped into the light, bowed to Stef as she climbed out of the car. ‘Greetings,’ he said in his cultured British accent. He made no attempt to shake Stef’s hand, but wafted his fingers through the lintel of the doorway; pixels scattered from his fingertips like fairy dust. ‘At least in European manners, this is how to announce one is only a virtual presence. I hope this suit – that’s how I think of my various bodies, as “suits” – is acceptable to you both.’

  ‘It’s fine,’ Penny said. She was looking steadily at Stef. Then she approached her sister, one pace, two.