Quarantine

Nothing happens, nothing changes—which is exactly as it should be. I hold my hand up before my eyes, and it conspicuously fails to dissolve into a blur of alternatives. The whole room remains as solid, as ordinary, as ever. So far as I can judge, my mental state is entirely unaltered—except for a predictable surge of relief to find that I’m still not paralysed, blind or detectably insane. Lui might have known what he was doing, after all. The mod might even be working.

In which case, I am now smeared—even if there are no observable consequences whatsoever. The uniqueness, the solidity, the utter normalcy of everything, is a product of the fact that I will be collapsed at some time in the future—this time, without Po-kwai’s eigenstate mod to distort the probabilities, or to mix and confuse the alternatives.

I will be collapsed? Perhaps it makes more sense to assume that I’m ‘already’ being collapsed—at a time which only seems to lie in the future—and this whole experience is arising ‘retrospectively’ from that process. When the spin of an ion is measured, Po-kwai assured me, that is when it becomes definite, not before.

I laugh out loud. In spite of everything—Laura’s feats of escapology, Po-kwai’s success with the ions, my own impossible mod failures—it’s still not real to me. And in spite of the fact that I know that this is the heart of the true Ensemble… it still sounds like a load of pretentious, inconsequential, undergraduate philosophical crap. For all I know, I’ve just installed the Emperor’s new mod.

I bring back the menu, tick the OFF switch —

— and wonder: what about all of the versions of me who didn’t just do that? Have they been destroyed by the wave-collapsing pathways in my skull… even though half of them may have been scattered around the room—or across the city—by now?

They must have been—destroyed by me, or destroyed by some other observer.

All of them?

Forget the collapse-inhibiting mod—that changes nothing but the timing. The ordinary course of events must add up to normality. However frequently or infrequently the brain performs the collapse, it must reach out and destroy even the most far-flung, improbable states. If not, then these untouched states would persist indefinitely. There’s no point appealing to other observers to clean things up; they’d do the job imperfectly, too. If the collapse were not all-consuming, then the single, solid branch of reality wouldn’t be unique at all. It would lie in the centre of a huge void of depleted alternatives, but that void would be finite—and beyond it would lie an infinite thicket of fine branches, the ghosts of improbabilities too remote to have been destroyed. And that’s just not the way things are.

I start my own experiments while Po-kwai is still waiting for the next phase of her work to begin. Perhaps that’s pointless, given that—so far—the most dramatic effects have occurred on those nights when she’s actually used the eigenstate mod successfully. But I can’t see the harm in trying—and I might as well be optimistic. If my own use of the eigenstate mod remains tied absolutely to hers, it could end up taking me years to achieve the simplest tricks—let alone any massively improbable cross-town burglaries.

Po-kwai developed her skills working with the simplest possible systems: silver ions carefully prepared to consist of an equal mixture of just two states. I don’t have access to anything so pure, but I can still work on the same basic principle: taking a system which would normally collapse according to well-known probabilities, and trying to skew the odds. Both von Neumann and Hypernova have facilities for true random-number generation—as opposed to the deterministic pseudo-random sequences produced by purely algorithmic means. They employ groups of neurons specially tailored for the purpose, balanced on a fractal knife-edge between firing and not firing, stuttering chaotically in the sway of nothing but intracellular chemical fluctuations and, ultimately, thermal noise. Ordinarily, the system should collapse in such a way as to generate random numbers spread uniformly throughout a specified range; any skew, any bias, would mean that I’d succeeded in changing the probabilities—favouring one of the system’s states to make it more likely to be the sole survivor of the collapse—just as Po-kwai succeeded in increasing the probability of the up state in her silver ions.

I spend three nights trying to influence von Neumann’s random numbers, with no success… which is no great surprise. The combination of visualization and wishful thinking I employ—for want of anything better—seems more like an exercise for aspiring psychics than an attempt to give a precise command to a specific neural mod, whoever’s skull it happens to be in. Lui is no help; he’s never so much as caught a glimpse of a description of the eigenstate mod’s interface. So, I laboriously steer a conversation with Po-kwai onto the topic (and probably succeed in sounding far less natural than if I’d just asked her, out of the blue).

She says, ‘I’ve told you: I don’t remember using that part of the mod; I just switch on the collapse-inhibitor, then sit back and watch the ions. The two functions are independent. The whole thing was installed as a single package, but in effect, it’s two separate mods. The eigenstate mod only works when it’s smeared… and while I’m smeared, I can—evidently—operate this smeared mod. After the collapse, though, I know nothing about it.’

‘But… how can you have learnt to do something that you don’t even remember doing?’

‘Not all skills rely on episodic memory. Do you remember learning how to walk? Sure, if I’ve grown better at manipulating eigenstates, then that skill must be embodied in some kind of neural structure, somewhere in my brain—but certainly not as a conventional memory, and probably not in any form which could ever make sense to me, or be of use to me, while I’m collapsed. I mean, the eigenstate mod is a neural system which only works when it’s smeared, so there’s no reason why other parts of my brain—pathways which formed naturally, during the course of the experiment—might not also work only when smeared.’

‘You’re saying that when you’re smeared, you know how to work the eigenstate mod—but the knowledge is encoded in your brain in a way that’s unreadable when you’re collapsed?’

‘Exactly. The knowledge must have been stored in the brain while I was smeared… so it’s hardly surprising that I can only decipher it when I’m smeared again.’

‘But… how can information about being smeared survive from one time to the next, when the collapse wipes out every last trace of every eigenstate but one?’

‘Because it doesn’t! That’s only true if the eigenstates don’t have a chance to interact—and the eigenstate mod means they do interact. There’s nothing new, in principle, about smeared systems leaving proof that they’ve been smeared; half the critical experiments in early quantum mechanics relied on it. Indelible evidence of multiple states co-existing is more than a century old: electron diffraction patterns, holograms… any kind of interference effect. You know, the old photographic holograms were made by splitting a laser beam in two, bouncing one beam off the object, then recombining the beams and photographing the interference pattern.’

‘What’s that got to do with smearing?’

‘How do you split a laser beam in two? You point it at a sheet of glass with a very thin coating of silver, angled at forty-five degrees to the beam; half the light is reflected to the side, while the rest passes straight through. But when I say “half the light is reflected,” I don’t mean every second photon is reflected—I mean every individual photon is smeared into an equal mixture of a state where it’s reflected, and a state where it passes straight through.

‘And if you try to observe which path each photon takes, you collapse the system into a single state—and you destroy the interference pattern, you ruin the hologram. But if you let the beams recombine, unmolested, giving the two states a chance to interact, then the hologram remains as tangible, lasting proof that both states existed simultaneously.

‘So, maybe interactions between different versions of my brain can leave some kind of permanent record of the experience of being smeared. And just as a laser-light hologram is an indecipherable mess to the naked eye— bearing no resemblance to the object whatsoever, until the image is reconstructed—this information stored in my brain may be incomprehensible to me, but presumably it comprises skills that are useful to the smeared Po-kwai.’

I digest this. Okay. But even if there is this way for “the smeared Po-kwai” to learn things that you don’t know about… what did you actually do to encourage her to learn what you wanted her to learn?’