Quarantine

by Greg Egan

  I look up at the sky, and catch sight of a faint point of light above the fading glow in the west. I stare at it for ten long seconds, before I realize it's only Venus.

  The woman at Third Hemisphere frowns and says, 'You're early. Come back in two hours.' 'Speed it up. I'll pay you -'

  She laughs. 'You can pay me whatever you like, it won't make any difference. The machine's been programmed, it's building your nanomachines; nothing's going to "speed it up" now.'

  Nothing? What if I paid her to leave me alone with the synthesizer, then smeared - and didn't collapse until I had Ensemble installed in my head, allowing me to choose the whole sequence of events to have taken place in some 'impossibly' short time? There'd be no risk of the machine's accelerated action resulting in a defective mod . . . since if the mod turned out to be defective, the miraculous acceleration would never have taken place.

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  Or would it? What if I introduced some subtle flaw which didn't manifest itself immediately? I stare at the silent machine - which looks disconcertingly like an upmarket beverage dispenser - and I baulk at the prospect of having it stray from the safety of known probabilities. It's already juggling with matter on a molecular scale, subject to quantum uncertainties; I don't want it rendered capable of spitting out anything at all. Ensemble is my only advantage; if I take short cuts and screw it up, I'll have no chance whatsoever of finding Lui in time.

  I say, 'I'll wait outside. Call me, the instant -' The woman nods, amused. 'You sound like an expectant father.'

  I should prime; go into stake-out mode and pass the time effortlessly . . . but some part of me violently resists the idea. To prime, now, would be irresponsible, escapist, unnatural . . .

  I contemplate this alien rhetoric numbly, more bemused than horrified. I've escaped the grip of the loyalty mod by collapsing in some unlikely way - did I expect to end up perfectly unchanged in every other respect? Perhaps an increased distaste for neural mods was a necessary - or highly probable - concomitant of wanting to be set free.

  So I wait like a human: sick with pointless, unproductive fears. Trying to imagine the unimaginable. If the whole planet smeared, permanently . . . what exactly would people experience? Nothing - because there is no collapse to make anything real? Or everything - because there is no collapse to make anything less than real? Everything, separately - one isolated consciousness per eigenstate, like the many-worlds model brought to life? Or everything, simultaneously - a cacophony of superimposed possibilities? What I've been through myself - or at least those memories which have survived the collapse -might bear no resemblance to the nature of things when there'll be no collapse at any future time. Once there's

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  nothing to make the past unique, the whole experience could be radically different.

  Whatever the case, I'm certain of one thing: Lui can't be allowed to succeed.

  I only hope that my smeared self agrees.

  The Third Hemisphere woman doesn't ask what it is I'm so desperate to try. I transfer the money. She hands me the vial, and I use it at once.

  She says, Ί hope we'll do business again.'

  I stop pinching my nostril. Ί doubt that very much.'

  I sniff twice. A drop of fluid falls to the floor.

  As I walk out of the alley, I instruct MindTools to notify me when Ensemble proclaims its existence. The expert system predicted two to three hours for installation, depending on the contingencies of the user's neural anatomy.

  Back on the main road, the shopfronts are dazzling with holograms of merchandise; photorealism is out of style this year, and everything from shoes to cooking pots is rendered incandescent. I reach up and pass my hand back and forth through the spinning front wheel of a bicycle hovering two metres above the pavement, half expecting a shock of pain from the white-hot spokes.

  I stand awhile, watching the crowd. / could still buy my way out of this. In two hours, I could be on the other side of the world. Maybe Laura was wrong; maybe whatever happens here could be confined, somehow. Once it's clear that there's an epidemic, if they closed the borders . . .

  Against people who can tunnel through any kind of barrier? What do I think they're going to do? Drop the city into a black hole? Build their own Bubble?

  Karen says, 'You stole the mod once; you can do it again. What does Lui have to stop you that BDI didn't?'

  'And if he's already released the EndamoebaT

  'You don't know he's done that.'

  Ί don't know he hasn't.'

  I stare up at the sky, and fight down a wave of vertigo.

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  The truth is, The Bubble has never confined us; it's merely rendered our confinement visible. The shock was not one of limitation; the shock was being forced to confront the alternative, the infinite freedom beyond.

  I say, Ί think I'm getting Bubble Fever.'

  Karen shakes her head. 'Bubble Fever,' she says, 'has gone right out of fashion.'

  I have no choice but to wait for Ensemble - but that's no reason to delay preparing the tools I'm going to need to help me find Lui, once the mod is functional. Back in my flat, I write a small von Neumann program which will accept a six-digit number as input, consult Deja Vu's geographical database, and generate a map reference to a forty-five-metre square of dry land, somewhere in the city. It takes me a while to decide what else to rule out, besides water; there are plenty of land-use categories that seem 'obviously' pointless to search - too exposed, too inaccessible, or just plain ludicrous - but I can't decide where to draw the line, so I end up keeping most of them in. Airport runways are excluded, but any versions of me sent to investigate some corner of a rugby field or sewage treatment plant will just have to live with the knowledge that they probably won't see out the night.

  I stare at the map in my head and think: By morning, this city is going to be smothered with my invisible corpses. And to the sole inheritor of my past, the 'miraculous' survivor of one more collapse . . . these deaths will seem less real than ever.

  They're real to me, though. They're in my future, all of them.

  The message flashes up, just before midnight: [MindTools: Broadcast received.

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  Sender ID: Ensemble (Third Hemisphere, $80,000).

  Category: Autogenesis completion.]

  I try to invoke it, but no interface window, no control panel, appears in my mind's eye - which is no great surprise; this mod isn't mine to use. So I sit on the bed and invoke Hyper nova, and bring back to life the being that Ensemble was made for.

  What did Laura's spokesperson call him? Childlike? Unreliable? And if he's made of a billion endlessly dividing versions of me, what am I to him? A microscopic nonentity - as a single blood cell, or a single neuron, is to me? But then, there's no doubt that I'm forced to respect the needs of my blood cells and neurons, en masse. I've swayed him a hundred times before; surely one more miracle isn't unthinkable - especially when I'm so sure that I'm almost unanimous in wanting it. What versions of me could possibly wish for Lui to succeed?

  I wait ten minutes, then step out of the room.

  I had some fantasy of slinking unseen through side streets and back alleys, but a fantasy is all it was. Midnight is peak hour for tourists, and everyone who trades with them; the side streets and alleys are packed. I push through the crowds, thinking: Either I've been collapsed, long ago - or I'm practically doing Lui's work for him. If I'm preventing the collapse of everyone who observes me, and everyone who observes them . . . and that's true for every version of me as I spread out across the city . . . then how long before the whole planet is smeared? Supposedly a day or two, for Laura - but I can't count on the same time frame applying to me. She might have had ways to minimize the effect, techniques to focus her presence. Me, I've set out to scour the city; I'm not focused at all.

  There's a busker at the entrance to the underground, wearing old-fashioned force-sensor gloves and playing a virtual violin - very skilfully, too ... if she really is causing the so
und, and not just miming to it. On the

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  escalators down, I take out the dice generator, throw six decahedrons, and feed the results into my map-dividing program.

  Throwing dice to find a madman? Why not consult Lui's horoscope? Why not consult the fucking / Chingl

  But I stifle my last vestiges of common sense, press on into the crowded station, and buy a ticket for my random destination.

  My target is a drab block of flats in a strip of residential land poking into the warehouse district north of the harbour. I approach with as much hope and caution as I can muster, torn between the clear understanding that the odds that / will be the one to find Lui are still only one in a million. . . and my irrelevant, but compelling, memories of having survived the collapse - 'despite the odds' - so many times before.

  The front entrance is locked, with a video paging system for visitors; the door slides open as I approach. I glance back over my shoulder as I step through into the foyer, shaken by a brief, but vivid, fantasy of the alternative: standing outside, waiting in vain for a miracle that's never going to come.

  Thirty storeys, with twenty flats each. I toss three decahedrons without thinking - and get eight, nine, five; I almost panic, but then I shake my head, laughing. I'm not giving up that easily; I can play this game any way I like. I subtract six hundred and head for the stairs. If there are more of me in some flats than others, that's hardly the end of the world.

  I take the stairs quietly. The building is all but silent; there's faint music from the third floor, and a child crying on the seventh; the occasional shudder of running water and flushing toilets. The banality of it all is, absurdly, reassuring - as if by some fanciful law of conservation of implausibility, those of me destined to fail might be hearing some freakish proof that their luck has been wasted . . . like the same incarnation of Angela Renfield's 'Paradise' being played, coincidentally, in every flat.

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  By the tenth floor, I've made up my mind: if Lui's not in 295, ΓΗ search the whole building from top to bottom. / have nothing to lose. And if he's nowhere in the building? Then I'll search the entire street.

  I see movement ahead as I step out onto the fourteenth floor, but it's only a squat cleaning robot gliding along the corridor, vacuuming the ragged carpet and sucking graffiti off the walls.

  I hesitate outside Room 295, but only for a moment. I draw my gun and try the door.

  It opens.

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  13

  Lui is standing beside a table cluttered with laboratory glassware, watching the liquid in a culture flask being stirred by a spinning magnet. He looks up angrily, then his expression suddenly softens, and - in almost welcoming tones - he says, 'Nick. I didn't recognize you.'

  'Step back, and put your hands on your head.'

  He complies.

  Do I collapse now - to seal my victory, to make it irreversible? Not yet. This is no time to be complacent; I don't know what further improbable feats might be required.

  I take a deep breath. 'Have you released the EndamoebaV He shakes his head innocently. 'If you're lying, I'll -'

  What? And how would I know? The neighbourhood hasn't visibly dissolved into a quadrillion versions - but then, neither have I, visibly.

  'Why not?'

  He gives me a slightly bemused look, as if he can't quite believe that I need to ask. 'The strain sent to NeoMod was attenuated. I had no way of knowing what tests they might have done on it; I couldn't risk sending them anything too far out of the ordinary. A place like that may be willing to bend the rules - to make a puppet mod for one gangster to slip into another's drink - but if they'd found out they were dealing with something that could spread like the plague, they'd hardly have gone ahead and integrated the nanomachines.' He nods at the flask being stirred. 'I'm culturing it with a retrovirus that puts a crucial promoter sequence back into the genome. The version they saw was no more spectacular than any of the standard illegals. This is the real thing.'

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  I have no reason to believe him - but why else would he be messing around with this equipment, instead of wandering the streets, spreading the vector? I glance down at the flask; it looks like it's thoroughly sealed, which seems bizarre . . . but then, he wouldn't have wanted to risk smearing himself while engaged in something so crucial - just as I chose to stay collapsed during the synthesis of Ensemble.

  I ask, 'Who else has copies of the mod?'

  'No one.'

  'Yeah? There's nobody else in the Canon who you persuaded to see things your way?'

  'No.' He hesitates, then says matter-of-factly, 'You were the only one who might have understood.'

  I laugh drily. 'Don't waste your breath. I'm not part of the Canon any more; I seem to have tunnelled out of that particular asylum.' And you'll be following me, soon enough - albeit by more conventional means.

  He shakes his head. 'The loyalty mod has nothing to do with it. You've smeared - and collapsed - often enough to understand what there is to be gained.'

  'Gained?' The truth is, I can't begin to grasp the magnitude of what's been averted; perhaps if I'd caught him with something more innocuous - like a medium-sized lump of plutonium -1 might have been able to feel an appropriate sense of reprieve.

  I say, Ί do understand: this is your vision of the true Ensemble - and the loyalty mod has everything to do with that. I don't blame you for being unable to stop yourself -1 remember what that doublethink is like - but admit it: you know the whole idea is obscene beyond belief. You've known that all along. You're talking about blasting twelve billion people into some kind of metaphysical nightmare -'

  'I'm talking about the end of twelve billion people dying every microsecond. I'm talking about the end of the death of possibilities.'

  'The collapse isn't death.'

  'No? Think about those versions of yourself who didn't find me -'

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  I laugh, bitterly. 'You're the one who taught me not to. But I'll grant you that: for them - if they experience anything at all - it must seem like impending death. But not for ordinary people. And not for me, not ever again. People make choices; only one eigenstate survives. That's not a tragedy, that's who we are, that's the way it has to be.'

  'You know better than that.' 'But I don't.'

  'Don't you mourn the versions of yourself who persuaded Po-kwai to use Ensemble for you?' 'No. Why should I?'

  'They must have been close, I think. Lovers, perhaps.'

  I'm shaken by the thought, but I say calmly, 'It means nothing to me. He was never real. She has no memory, I have no memory -'

  'But you can imagine how happy they might have been. What do you call the end of that happiness, if not death?'

  I shrug. 'People die every day. I can't change that.'

  'But you can. Immortality is possible. Heaven on Earth is possible.'

  I laugh. 'Heaven on Earth? What are you now - a millenarian? You can't know any more than I do what permanent smearing would be like. But if Heaven on Earth is part of it, it will co-exist with Hell. If no eigenstate is destroyed, then every conceivable kind of suffering -'

  He nods, unfazed. 'Oh yes. And every conceivable kind of happiness. And everything in between. Everything:

  'And the end of choice, the death of free will -' 'The death of nothing. How can restoring the diversity

  of the universe be seen as taking something away?' I shake my head. Ί honestly don't care. Just -' 'So you'd deny everyone else the choice?' I laugh with disbelief. 'You're the lunatic who planned

  to force your will -' 'Not at all. Once the planet is smeared, everyone will be

  linked. The smeared human race can decide for itself

  whether or not to recollapse.'

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  'And you'd call the judgement of this . . . infant collective consciousness ... a fair way to decide the fate of the planet? Even the Bubble Makers had more respect for humanity than that.'

  'Of course they have respect for humanity.
They comprise human beings themselves.'

  'Laura comprises -'

  'No: all of them. What do you think they are? Some exotic lifeform from another planet? Do you think they could have programmed Laura's genes to keep her from collapsing, to give her the ability to manipulate eigen-states, if they weren't smeared humans themselves?'

  'But -'

  'The collapse has a finite horizon; there are always eigenstates beyond it. Do you think none of them contain human beings? The Bubble Makers are the residues of ourselves - they're made up of versions of us so improbable that they've escaped the collapse. All I want to do is give us the chance to rejoin them.'

  My head is throbbing; I glance down at the flask again. It may be sealed, but I'll be a lot happier once it's been consigned to an acid bath or a high-temperature incinerator.

  I gesture with the gun. 'Go and sit in the chair. I'm afraid I'm going to have to tie you up while I find out how to get rid of this shit.'

  'Nick, please, just -'

  I say evenly, 'Listen: if you make trouble, I'm not going to wound you; I can't risk having you thrashing around the room. If I shoot you, I'll have to kill you. So go and sit in the chair.'

  He makes as if to comply, but then hesitates. I suddenly realize that he's closer to the table than I thought; not within arm's reach of the flask, but only a step away.

  He says, 'Just think about it, that's all I'm asking! There must be states beyond The Bubble full of the most incredible things! Miracles. Dreams.' His face glows with pure rapture, all traces of the old turmoil and self-disgust abolished. Maybe he's put an end to the doublethink after

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