by Greg Egan
Francine said, “You can. Nothing you’ve done will ever disappear from under your feet. No one’s going to march up and take it away from you.”
“I know.” My skin crawled, at the image of some less favored alter ego turning up on our doorstep, demanding his dues. “That seems so fucking selfish, though. I don’t want everything that makes me happy to be at the expense of someone else. I don’t want every choice to be like … fighting other versions of myself for the prize in some zero-sum game.”
“No.” Francine hesitated. “But if the reality is like that, what can you do about it?”
Her words hung in the darkness. What could I do about it? Nothing. So did I really want to dwell on it, corroding the foundations of my own happiness, when there was absolutely nothing to be gained, for anyone?
“You’re right. This is crazy.” I leaned over and kissed her. “I’d better let you get to sleep.”
“It’s not crazy,” she said. “But I don’t have any answers.”
#
The next morning, after Francine had left for work, I picked up my notepad and saw that she’d mailed me an e-book: an anthology of cheesy “alternate (sic) history” stories from the ’90s, entitled My God, It’s Full of Tsars! “What if Gandhi had been a ruthless soldier of fortune? What if Theodore Roosevelt had faced a Martian invasion? What if the Nazis had had Janet Jackson’s choreographer?”
I skimmed through the introduction, alternately cackling and groaning, then filed the book away and got down to work. I had a dozen minor administrative tasks to complete for UNESCO, before I could start searching in earnest for my next position.
By mid-afternoon, I was almost done, but the growing sense of achievement I felt at having buckled down and cleared away these tedious obligations brought with it the corollary: someone infinitesimally different from me – someone who had shared my entire history up until that morning – had procrastinated instead. The triviality of this observation only made it more unsettling; the Delft experiment was seeping into my daily life on the most mundane level.
I dug out the book Francine had sent and tried reading a few of the stories, but the authors’ relentlessly camp take on the premise hardly amounted to a reductio ad absurdum, or even a comical existential balm. I didn’t really care how hilarious it would have been if Marilyn Monroe had been involved in a bedroom farce with Richard Feynman and Richard Nixon. I just wanted to lose the suffocating conviction that everything I had become was a mirage; that my life had been nothing but a blinkered view of a kind of torture chamber, where every glorious reprieve I’d ever celebrated had in fact been an unwitting betrayal.
If fiction had no comfort to offer, what about fact? Even if the Many Worlds cosmology was correct, no one knew for certain what the consequences were. It was a fallacy that literally everything that was physically possible had to occur; most cosmologists I’d read believed that the universe as a whole possessed a single, definite quantum state, and while that state would appear from within as a multitude of distinct classical histories, there was no reason to assume that these histories amounted to some kind of exhaustive catalog. The same thing held true on a smaller scale: every time two people sat down to a game of chess, there was no reason to believe that they played every possible game.
And if I’d stood in an alley, nine years before, struggling with my conscience? My subjective sense of indecision proved nothing, but even if I’d suffered no qualms and acted without hesitation, to find a human being in a quantum state of pure, unshakeable resolve would have been freakishly unlikely at best, and in fact was probably physically impossible.
“Fuck this.” I didn’t know when I’d set myself up for this bout of paranoia, but I wasn’t going to indulge it for another second. I banged my head against the desk a few times, then picked up my notepad and went straight to an employment site.
The thoughts didn’t vanish entirely; it was too much like trying not to think of a pink elephant. Each time they recurred, though, I found I could shout them down with threats of taking myself straight to a psychiatrist. The prospect of having to explain such a bizarre mental problem was enough to give me access to hitherto untapped reserves of self-discipline.
By the time I started cooking dinner, I was feeling merely foolish. If Francine mentioned the subject again, I’d make a joke of it. I didn’t need a psychiatrist. I was a little insecure about my good fortune, and still somewhat rattled by the news of impending fatherhood, but it would hardly have been healthier to take everything for granted.
My notepad chimed. Francine had blocked the video again, as if bandwidth, even here, was as precious as water.
“Hello.”
“Ben? I’ve had some bleeding. I’m in a taxi. Can you meet me at St Vincent’s?”
Her voice was steady, but my own mouth went dry. “Sure. I’ll be there in fifteen minutes.” I couldn’t add anything: I love you, it will be all right, hold on. She didn’t need that, it would have jinxed everything.
Half an hour later, I was still caught in traffic, white-knuckled with rage and helplessness. I stared down at the dashboard, at the real-time map with every other gridlocked vehicle marked, and finally stopped deluding myself that at any moment I would turn into a magically deserted side-street and weave my way across the city in just a few more minutes.
In the ward, behind the curtains drawn around her bed, Francine lay curled and rigid, her back turned, refusing to look at me. All I could do was stand beside her. The gynecologist was yet to explain everything properly, but the miscarriage had been accompanied by complications, and she’d had to perform surgery.
Before I’d applied for the UNESCO fellowship, we’d discussed the risks. For two prudent, well-informed, short-term visitors, the danger had seemed microscopic. Francine had never traveled out into the desert with me, and even for the locals in Basra the rates of birth defects and miscarriages had fallen a long way from their peaks. We were both taking contraceptives; condoms had seemed like overkill. Had I brought it back to her, from the desert? A speck of dust, trapped beneath my foreskin? Had I poisoned her while we were making love?
Francine turned toward me. The skin around her eyes was gray and swollen, and I could see how much effort it took for her to meet my gaze. She drew her hands out from under the bedclothes, and let me hold them; they were freezing.
After a while, she started sobbing, but she wouldn’t release my hands. I stroked the back of her thumb with my own thumb, a tiny, gentle movement.
2020
“How do you feel now?” Olivia Maslin didn’t quite make eye contact as she addressed me; the image of my brain activity painted on her retinas was clearly holding her attention.
“Fine,” I said. “Exactly the same as I did before you started the infusion.”
I was reclining on something like a dentist’s couch, halfway between sitting and lying, wearing a tight-fitting cap studded with magnetic sensors and inducers. It was impossible to ignore the slight coolness of the liquid flowing into the vein in my forearm, but that sensation was no different than it had been on the previous occasion, a fortnight before.
“Could you count to ten for me, please.”
I obliged.
“Now close your eyes and picture the same familiar face as the last time.”
She’d told me I could choose anyone; I’d picked Francine. I brought back the image, then suddenly recalled that, the first time, after contemplating the detailed picture in my head for a few seconds – as if I was preparing to give a description to the police – I’d started thinking about Francine herself. On cue, the same transition occurred again: the frozen, forensic likeness became flesh and blood.
I was led through the whole sequence of activities once more: reading the same short story (“Two Old-Timers” by F. Scott Fitzgerald), listening to the same piece of music (from Rossini’s The Thieving Magpie), recounting the same childhood memory (my first day at school). At some point, I lost any trace of anxiety about repeating my earl
ier mental states with sufficient fidelity; after all, the experiment had been designed to cope with the inevitable variation between the two sessions. I was just one volunteer out of dozens, and half the subjects would be receiving nothing but saline on both occasions. For all I knew, I was one of them: a control, merely setting the baseline against which any real effect would be judged.
If I was receiving the coherence disruptors, though, then as far as I could tell they’d had no effect on me. My inner life hadn’t evaporated as the molecules bound to the microtubules in my neurons, guaranteeing that any kind of quantum coherence those structures might otherwise have maintained would be lost to the environment in a fraction of a picosecond.
Personally, I’d never subscribed to Penrose’s theory that quantum effects might play a role in consciousness; calculations dating back to a seminal paper by Max Tegmark, twenty years before, had already made sustained coherence in any neural structure extremely unlikely. Nevertheless, it had taken considerable ingenuity on the part of Olivia and her team to rule out the idea definitively, in a series of clear-cut experiments. Over the past two years, they’d chased the ghost away from each of the various structures that different factions of Penrose’s disciples had anointed as the essential quantum components of the brain. The earliest proposal – the microtubules, huge polymeric molecules that formed a kind of skeleton inside every cell – had turned out to be the hardest to target for disruption. But now it was entirely possible that the cytoskeletons of my very own neurons were dotted with molecules that coupled them strongly to a noisy microwave field in which my skull was, definitely, bathed. In which case, my microtubules had about as much chance of exploiting quantum effects as I had of playing a game of squash with a version of myself from a parallel universe.
When the experiment was over, Olivia thanked me, then became even more distant as she reviewed the data. Raj, one of her graduate students, slid out the needle and stuck a plaster over the tiny puncture wound, then helped me out of the cap.
“I know you don’t know yet if I was a control or not,” I said, “but have you noticed significant differences, with anyone?” I was almost the last subject in the microtubule trials; any effect should have shown up by now.
Olivia smiled enigmatically. “You’ll just have to wait for publication.” Raj leaned down and whispered, “No, never.”
I climbed off the couch. “The zombie walks!” Raj declaimed. I lunged hungrily for his brain; he ducked away, laughing, while Olivia watched us with an expression of pained indulgence. Die-hard members of the Penrose camp claimed that Olivia’s experiments proved nothing, because even if people behaved identically while all quantum effects were ruled out, they could be doing this as mere automata, totally devoid of consciousness. When Olivia had offered to let her chief detractor experience coherence disruption for himself, he’d replied that this would be no more persuasive, because memories laid down while you were a zombie would be indistinguishable from ordinary memories, so that looking back on the experience, you’d notice nothing unusual.
This was sheer desperation; you might as well assert that everyone in the world but yourself was a zombie, and you were one, too, every second Tuesday. As the experiments were repeated by other groups around the world, those people who’d backed the Penrose theory as a scientific hypothesis, rather than adopting it as a kind of mystical dogma, would gradually accept that it had been refuted.
#
I left the neuroscience building and walked across the campus, back toward my office in the physics department. It was a mild, clear spring morning, with students out lying on the grass, dozing off with books balanced over their faces like tents. There were still some advantages to reading from old-fashioned sheaves of e-paper. I’d only had my own eyes chipped the year before, and though I’d adapted to the technology easily enough, I still found it disconcerting to wake on a Sunday morning to find Francine reading the Herald beside me with her eyes shut.
Olivia’s results didn’t surprise me, but it was satisfying to have the matter resolved once and for all: consciousness was a purely classical phenomenon. Among other things, this meant that there was no compelling reason to believe that software running on a classical computer could not be conscious. Of course, everything in the universe obeyed quantum mechanics at some level, but Paul Benioff, one of the pioneers of quantum computing, had shown back in the ’80s that you could build a classical Turing machine from quantum mechanical parts, and over the last few years, in my spare time, I’d studied the branch of quantum computing theory that concerned itself with avoiding quantum effects.
Back in my office, I summoned up a schematic of the device I called the Qusp: the quantum singleton processor. The Qusp would employ all the techniques designed to shield the latest generation of quantum computers from entanglement with their environment, but it would use them to a very different end. A quantum computer was shielded so it could perform a multitude of parallel calculations, without each one spawning a separate history of its own, in which only one answer was accessible. The Qusp would perform just a single calculation at a time, but on its way to the unique result it would be able to pass safely through superpositions that included any number of alternatives, without those alternatives being made real. Cut off from the outside world during each computational step, it would keep its temporary quantum ambivalence as private and inconsequential as a daydream, never being forced to act out every possibility it dared to entertain.
The Qusp would still need to interact with its environment whenever it gathered data about the world, and that interaction would inevitably split it into different versions. If you attached a camera to the Qusp and pointed it at an ordinary object – a rock, a plant, a bird – that object could hardly be expected to possess a single classical history, and so neither would the combined system of Qusp plus rock, Qusp plus plant, Qusp plus bird.
The Qusp itself, though, would never initiate the split. In a given set of circumstances, it would only ever produce a single response. An AI running on the Qusp could make its decisions as whimsically, or with as much weighty deliberation as it liked, but for each distinct scenario it confronted, in the end it would only make one choice, only follow one course of action.
I closed the file, and the image vanished from my retinas. For all the work I’d put into the design, I’d made no effort to build the thing. I’d been using it as little more than a talisman: whenever I found myself picturing my life as a tranquil dwelling built over a slaughter house, I’d summon up the Qusp as a symbol of hope. It was proof of a possibility, and a possibility was all it took. Nothing in the laws of physics could prevent a small portion of humanity’s descendants from escaping their ancestors’ dissipation.
Yet I’d shied away from any attempt to see that promise fulfilled, firsthand. In part, I’d been afraid of delving too deeply and uncovering a flaw in the Qusp’s design, robbing myself of the one crutch that kept me standing when the horror swept over me. It had also been a matter of guilt: I’d been the one granted happiness, so many times, that it had seemed unconscionable to aspire to that state yet again. I’d knocked so many of my hapless cousins out of the ring, it was time I threw a fight and let the prize go to my opponent instead.
That last excuse was idiotic. The stronger my determination to build the Qusp, the more branches there would be in which it was real. Weakening my resolve was not an act of charity, surrendering the benefits to someone else; it merely impoverished every future version of me, and everyone they touched.
I did have a third excuse. It was time I dealt with that one, too.
I called Francine.
“Are you free for lunch?” I asked. She hesitated; there was always work she could be doing. “To discuss the Cauchy-Riemann equations?” I suggested.
She smiled. It was our code, when the request was a special one. “All right. One o’clock?”
I nodded. “I’ll see you then.”
#
Francine was twenty minutes la
te, but that was less of a wait than I was used to. She’d been appointed deputy head of the mathematics department eighteen months before, and she still had some teaching duties as well as all the new administrative work. Over the last eight years, I’d had a dozen short-term contracts with various bodies – government departments, corporations, NGOs – before finally ending up as a very lowly member of the physics department at our alma mater. I did envy her the prestige and security of her job, but I’d been happy with most of the work I’d done, even if it had been too scattered between disciplines to contribute to anything like a traditional career path.
I’d bought Francine a plate of cheese-and-salad sandwiches, and she attacked them hungrily as soon as she sat down. I said, “I’ve got ten minutes at the most, haven’t I?”
She covered her mouth with her hand and replied defensively, “It could have waited until tonight, couldn’t it?”
“Sometimes I can’t put things off. I have to act while I still have the courage.”
At this ominous prelude she chewed more slowly. “You did the second stage of Olivia’s experiment this morning, didn’t you?”
“Yeah.” I’d discussed the whole procedure with her before I volunteered.
“So I take it you didn’t lose consciousness, when your neurons became marginally more classical than usual?” She sipped chocolate milk through a straw.
“No. Apparently no one ever loses anything. That’s not official yet, but—”
Francine nodded, unsurprised. We shared the same position on the Penrose theory; there was no need to discuss it again now.
I said, “I want to know if you’re going to have the operation.”
She continued drinking for a few more seconds, then released the straw and wiped her upper lip with her thumb, unnecessarily. “You want me to make up my mind about that, here and now?”
