Quarantine

by Greg Egan

  'Then there's the many-worlds theory -'

  'Alternative histories, parallel universes . . .'

  'Exactly. In the many-worlds theory, the wave function

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  doesn't collapse. The entire universe splits into different versions, one for every possible measurement. One universe has a dead cat, and an experimenter who saw that it was dead; another universe has a live cat, and an experimenter who saw that it was alive. The trouble is, the theory doesn't say why any of this should happen - or even at what point the universe splits. Detector? Bottle? Cat? Human? It doesn't really answer anything.'

  'Maybe there are no answers; maybe it's all just a metaphysical quibble -'

  She shakes her head. 'Metaphysics has been an experimental science since the nineteen eighties. Although, personally, I'd like to think that the field really began in earnest from today.' She glances at her watch. 'Sorry, yesterday. Tuesday, the twenty-fourth of July, two thousand and sixty-eight.'

  She waits patiently - with a faintly smug grin - until it hits me:

  Ίη the brain? Somehow, you've shown that the collapse of the wave function happens in the brain?' 'Yes.'

  'But . . . how? What's any of this got to do with influencing the ions, making them all go one way? Aren't you using some kind of electromagnetic effect -'

  Wo/ No biological field could be strong enough -'

  'That's what I thought. But - how, then?'

  "The mod does two things. The first one is, it stops me collapsing the wave function; it disables the parts of the brain that normally do so. But if that was all it did, the ions would still be random, fifty-fifty . . . it's just that it would be you, Leung, Tse and Lui who'd be collapsing the system, instead of me.

  'But the mod also allows me to manipulate the eigen-states - now that I no longer clumsily, randomly, destroy all but one of them. It lets me change their relative strengths - and hence change the probabilities of the experiment's possible outcomes.

  'In theory, I suppose I could then collapse the wave function myself - but it'd make the experiment less

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  elegant to have the same person do both. So, the people in the control room collapse the whole system - which includes the silver ion, the fluorescent screen, and me -but only after I've changed the odds so they're no longer fifty-fifty.'

  'So . . . everyone in the control room is part of the experiment? That's why the histograms don't change until after you've spoken the ion's direction - because if we knew the results before you'd had a chance to influence the probabilities, we'd collapse the ions randomly?'

  'That's right.'

  I think it over for a moment. 'You say we collapse "the whole system". So you exist as a mixture, until we hear your voice?'

  'Yes.'

  'And what does that. . . feel like?'

  She laughs. 'That's the most frustrating thing of all: / don't know! I literally don't remember. Once I'm collapsed, I end up with only one set of memories; I only recall seeing one flash of light on the screen. I don't even remember what it's like to operate the eigenstate part of the mod. . . Didn't you ever wonder why it was taking me so long to make the thing work? And I don't know if I ever "see" two flashes, even for a moment; I suspect that my two states evolve too independently for that. What happens may be a bit like the many-worlds model, on a very small scale. Effectively, there may be two almost separate versions of me - if only for a fraction of a second before I'm collapsed. But whatever goes on in the rest of my brain, the two states of the mod definitely do interact -their wave functions interfere, strengthening one eigenstate and weakening the other. If not, the whole experiment would come to nothing - it would be just a metaphysical quibble.'

  I hesitate, bemused, and try to back-track through the discussion to the point where it derailed from reality. Finally, I say, 'Are you serious about any of this? You're not just stringing me along for a joke? Paying me back for crashing into your room? Because if that's it, you've won

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  - I concede defeat. You've got me to the point where I can't tell which parts are genuine, and which parts you're making up.'

  She looks hurt. Ί wouldn't do that. Everything I've told you is the truth.'

  'It's just. . . this is all beginning to sound like the kind of gibberish the quantum mystics spout -'

  She shakes her head vehemently. 'No, no - they claim there's some non-physical element to consciousness -something independent of the brain, some ill-defined "spiritual" entity which collapses the wave function. Yesterday's experiment proved them absolutely wrong. The parts of the brain which the mod disables don't do anything mystical; they perform a sophisticated - but perfectly comprehensible, perfectly physical- action.

  Ί know it all sounds bizarre - but the whole point is that, in fact, it's utterly commonplace. Everyone spends their whole life collapsing the systems they interact with. That's a very old idea; many of the pioneers of quantum mechanics believed that the observer had a crucial role to play - that a measuring device alone wasn't enough to collapse the wave function. But it's taken more than a century to pin down exactly where in the observer it happens.'

  I still don't know whether or not to believe a word of this - but she seems convinced, so at the very least, it's worth understanding precisely what she believes. I put aside my scepticism, and struggle to catch up.

  'Okay ... so a "measuring device" isn't enough, you have to have an "observer" - but what constitutes an observer? People, yes . . . but what about computers? What about cats?'

  'Ah. Existing computers, definitely not. Collapsing the wave function is a specific physical process - not an automatic by-product of a certain degree of intelligence, or self-awareness, or whatever - and computers simply haven't been designed to do it . . . although no doubt some will be, in the future.

  'As for cats ... my guess would be that they do it, but

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  I'm not exactly an expert on comparative neurophysiology, so don't take my word for it. It may be years before anyone gets around to finding out exactly which species do and don't. Then there's the whole question of the evolution of the trait - and just what "evolution" meant in an uncollapsed universe. People are going to spend decades unravelling all the implications.'

  I nod dumbly - and hope that she'll shut up for a moment, while I try to unravel a few implications myself. If all of this is true, what does it tell me about Laura? Could 'manipulating eigenstates' let her pick locks and elude security cameras? Maybe . . . but how could a chance mutation, or a random congenital abnormality, grant her such elaborate skills? The mere loss of the ability to collapse the wave function, yes - random damage can easily produce deficits. But what are the odds of brain damage resulting in the kind of sophisticated powers that Po-kwai claims the mod provides? And yet, Laura must have those powers; how else could she have escaped from the Hilgemann? And how else could the mod itself provide them? I can't believe that BDI designed the whole thing from scratch - in six months -simply by studying the normal human trait that Laura was missing.

  So, which is more preposterous: BDI inventing the neural manipulation of eigenstates, in less time than most companies take to develop a new games mod ... or a random event handing Laura - and BDI - the finished product on a silver platter?

  Po-kwai continues, 'It's a pretty sobering thought, though: until one of our ancestors learnt this trick, the universe must have been a radically different place from the one we know. Everything happened simultaneously; all possibilities coexisted. The wave function never collapsed, it just kept on growing more and more complex. And I know it sounds ludicrously - grandiosely - anthro-pocentric ... or geocentric ... to think that life on this one planet could have made such a difference, but with so much richness, so much complexity, perhaps it was

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  inevitable that, somewhere in the universe, a creature would evolve which undermined the whole thing, which annihilated the very diversity which had brought it into being.'

&nbs
p; She laughs uneasily; she seems almost embarrassed -the way some people become when recounting news of a disaster or atrocity.

  'It's not easy to come to terms with, but that's what we are. We're not just the universe "knowing itself - we're the universe decimating itself, in the very act of gaining that knowledge.'

  I stare at her, disbelieving. 'What are you saying? That the first animal on Earth with this trait. . . collapsed the whole universe?'

  She shrugs. 'Maybe it wasn't on Earth, but there's no reason why it can't have been. Somebody had to be first. And not quite the whole universe - one casual glance at the night sky would hardly have measured everything. It would have thinned out the possibilities considerably, though - fixed the Earth and the sun, for a start: condensed them out of the mixture of all possible arrangements of matter that might have occupied the solar system. Fixed the brightest stars to within the acuity of this creature's vision, discarding all the alternative possible configurations. Think of the constellations that might have been; the stars and the worlds that vanished forever when this ancestor of ours opened its eyes.'

  I shake my head. 'You can't be serious.'

  Ί am.'

  Ί don't believe you. What evidence is there? From one little experiment with silver ions, you're claiming that this hypothetical ancestor of humans - and possibly cats -transformed some kind of grand, glorious mixture of every possible universe that might have happened since the Big Bang. . . into whatever minuscule fraction of that would give this creature a single view of the night sky? Obliterating all the rest? Committing a kind of . . . cosmological genocide?'

  'Yes. Maybe literal genocide. Life - intelligent life -

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  need not collapse the wave function. If there was life before us which didn't collapse the wave, then we would have collapsed it. Which might have meant obliterating entire civilizations.'

  'And you think we're still doing it? Collapsing things light years away? Other stars? Other galaxies? Other forms of life? "Thinning out the possibilities?" Hacking away at the universe -just by observing it?'

  I laugh, suddenly remembering. 'Or rather, we were, until -'

  I stop myself mid-sentence, and close my eyes for a moment, giddy and claustrophobic. The unspoken conclusion unfolds in my brain regardless, and no mod in my skull seems able to render it harmless.

  Po-kwai says softly. 'Yeah. We were. Until The Bubble.'

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  8

  After a morning in the ion room, confirming that the previous night's results were no fluke, Po-kwai is given a fortnight to rest while preparations are made for the next phase of the experiment. Being confined to the building doesn't seem to bother her; she spends most of her time reading. 'It's what I'd be doing anyway,' she says. 'And if I can forget that I don't have any choice, the whole situation is perfect: peace and quiet - and reliable airconditioning. That's my idea of heaven.'

  The chant vanishes from my dreams. P3 functions perfectly. Karen does not return. I ask Lee Hing-cheung, circumspectly, about his own mods. It turns out that he has only Sentinel, MetaDossier and RedNet - and apart from the original problem during the ion experiments, he's had no trouble with any of them. My determination to uncover the cause of my own mods' erratic performance fades; I can't see the point in presenting myself to a doctor or neurotechnician when I have no symptoms - and I'm reluctant to risk disclosing the fact that I have a loyalty mod to people who aren't meant to know. I promise myself to seek help at the first sign of dysfunction, but as each day passes with no relapse, the hope that the problem has 'cured itself seems less and less unreasonable.

  Having feared some ingenious, but ultimately mundane, explanation for Laura's 'telekinesis' - having dreaded the burden of one more contradiction, one more disparity between my feelings about the Ensemble and the truth about its activities -Po-kwai's revelations are more than I could have hoped for. The Ensemble is probing the deepest questions of the nature of reality, the nature of humanity - and, possibly, the reasons for The Bubble as well. It fills me with shame to recall that I

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  seriously entertained the notion that the sole purpose of this grand alliance might have been the grubby exploitation of Laura's escapological skills. I should have known it was something higher.

  But if it had been 'grubby exploitation', after all? The Ensemble would have remained the most important thing in my life; the loyalty mod guarantees that. Fearing disillusionment and rejoicing in the affirmation of my faith are equally absurd. I spin this observation in my head, but it leads nowhere.

  I find Po-kwai's staggering contention - that life on Earth might be intrinsically inimical to the rest of the universe - equally intractable. The notion that humanity is, or was, part of a kind of cosmic necrosis, depleting the universe of possibilities, committing inadvertent genocide on a scale beyond comprehension, is easy enough to hold in the mind - to state as an isolated, abstract proposition - but impossible to pursue. My sense of horror rapidly gives way to disbelief; I feel like I've been led through one of those bogus mathematical 'proofs' which claim to demonstrate that one is equal to zero. I back out of this mental cul-de-sac and hunt for a flaw in the argument. When I come on duty in the late afternoon, Po-kwai breaks off her reading, and we resume the debate.

  I say, 'You've admitted, yourself: it's ludicrously geocentric'

  She shrugs. 'Only if we were the first. Maybe we weren't; maybe it happened on a thousand other planets, a billion years before it happened on Earth. I don't expect we'll ever know. But having pinned down the parts of the human brain which collapse the wave function, what would be geocentric would be assuming that every other sentient creature in the universe does exactly the same thing.'

  'But I'm not convinced that you have pinned it down. You haven't proved, conclusively, that you're not still collapsing the wave; you've only shown that the mod intervenes before the collapse - whatever causes it. Maybe

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  one of the old theories is right, after all - maybe the wave collapses whenever the system gets large enough, but the mod manages to act on a length scale just below the critical size ... it squeezes in its interference trick at the last opportunity.'

  'Then what about the parts of the brain that the mod disables? What's going on there?'

  Ί don't know. But if they look like they're "designed" to have some quantum effect, then maybe they're a crude attempt to do the very thing that the eigenstate part of the mod does - influence the way the wave collapses, rather than just accept the raw probabilities. Maybe evolution has given us all a small capacity to nudge the odds; you can't deny that that would have some survival value. And if the wave function has always been collapsing at random, whenever the system grew large enough, ever since the universe began . . . then all we're guilty of is beginning to evolve some control over the process.'

  She's sympathetic, but unmoved. 'If I don't invoke the collapse-inhibition part of the mod - if I don't disable those natural pathways - the whole effect disappears; the ions revert to randomness. That's the first thing we tested, the morning after the successful run. Okay, your theory might still be right - the natural pathways could interfere somehow with the mod's effects on the eigenstates, even if they had nothing to do with collapsing the wave. But if people had some capacity to "nudge the odds", I think it would have been discovered by now. I don't doubt that there are other explanations for the ion experiment - but what about The Bubble?'

  'There's no shortage of other explanations for that -1 must have heard at least a thousand in the last thirty years.'

  'And how many did you think made sense?'

  'None, to be honest. But how much sense does this one make? If the Bubble Makers were so vulnerable to our observations, how could they have survived for so long? How far out could telescopes see, before The Bubble? Billions of light years!'

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  'Yes, but we don't know what kind of damage - what degree of observation - they could tolerate. When the universe was tot
ally uncollapsed, maybe there were forms of life which relied on virtually all of that diversity - forms of life in which each individual was spread out across a large part of the entire span of eigenstates, occupying an enormous range of what we'd consider to be mutually exclusive possibilities. The first collapse, for them, would have been like . . . taking a thin slice out of a human's body, and throwing all the rest away.'

  'So how have the Bubble Makers survived? By being very thin to start with?'

  'Exactly! They must require a much narrower range of states. Maybe, for them, the effect was more like ... a deep ocean being made shallow. We may have observed galaxies billions of light years away - but we haven't even collapsed the solar system down to the last fragment of meteor dust. Planetary systems of distant stars would still have had a lot of freedom. And maybe an individual Bubble Maker could survive just about anything, short of a face-to-face confrontation with a human being, but increasingly accurate human astronomy was depleting the wave function - "draining the ocean" - to such a degree that constructing The Bubble, to keep us from making things worse, was the only way they could preserve their civilization.'

  Ί don't know

  She laughs. Ί don't know, either. And the whole point of The Bubble is that we never will know. I have other theories, though, if you don't like that one. Maybe the Bubble Makers are made of cold dark matter - axions, or some other weakly interacting particle which we've never been able to detect with much efficiency. If that were the case, we might have done them relatively little harm - but they decided that our technology was getting uncomfortably close to the point where it could start to affect them. There were plenty of astronomers searching for cold dark matter in the twenties and the early thirties - and their equipment was becoming a little more sensitive, and a

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  little more accurate, every year. Maybe we have them to blame.'