by Greg Egan
The more he thought and prayed about it, the more certain Jack became that he’d discerned the task required of him. No denunciation from the pulpits would suffice; people wouldn’t turn down the fruits of Stoney’s damnation on the mere say-so of the Church. Why would anyone reject such lustrous gifts, without a carefully reasoned argument?
Jack had been humiliated once, defeated once, trying to expose the barrenness of materialism. But might that not have been a form of preparation? He’d been badly mauled by Anscombe, but she’d made an infinitely gentler enemy than the one he now confronted. He had suffered from her taunts – but what was suffering, if not the chisel God used to shape his children into their true selves?
His role was clear, now. He would find Stoney’s intellectual Achilles heel, and expose it to the world.
He would debate him.
3
Robert gazed at the blackboard for a full minute, then started laughing with delight. “That’s so beautiful!”
“Isn’t it?” Helen put down the chalk and joined him on the couch. “Any more symmetry, and nothing would happen: the universe would be full of crystalline blankness. Any less, and it would all be uncorrelated noise.”
Over the months, in a series of tutorials, Helen had led him through a small part of the century of physics that had separated them at their first meeting, down to the purely algebraic structures that lay beneath spacetime and matter. Mathematics catalogued everything that was not self-contradictory; within that vast inventory, physics was an island of structures rich enough to contain their own beholders.
Robert sat and mentally reviewed everything he’d learned, trying to apprehend as much as he could in a single image. As he did, a part of him waited fearfully for a sense of disappointment, a sense of anticlimax. He might never see more deeply into the nature of the world. In this direction, at least, there was nothing more to be discovered.
But anticlimax was impossible. To become jaded with this was impossible. However familiar he became with the algebra of the universe, it would never grow less marvelous.
Finally he asked, “Are there other islands?” Not merely other histories, sharing the same underlying basis, but other realities entirely.
“I suspect so,” Helen replied. “People have mapped some possibilities. I don’t know how that could ever be confirmed, though.”
Robert shook his head, sated. “I won’t even think about that. I need to come down to Earth for a while.” He stretched his arms and leaned back, still grinning.
Helen said, “Where’s Luke today? He usually shows up by now, to drag you out into the sunshine.”
The question wiped the smile from Robert’s face. “Apparently I make poor company. Being insufficiently fanatical about darts and football.”
“He’s left you?” Helen reached over and squeezed his hand sympathetically. A little mockingly, too.
Robert was annoyed; she never said anything, but he always felt that she was judging him. “You think I should grow up, don’t you? Find someone more like myself. Some kind of soulmate.” He’d meant the word to sound sardonic, but it emerged rather differently.
“It’s your life,” she said.
A year before, that would have been a laughable claim, but it was almost the truth now. There was a de facto moratorium on prosecutions, while the recently acquired genetic and neurological evidence was being assessed by a parliamentary subcommittee. Robert had helped plant the seeds of the campaign, but he’d played no real part in it; other people had taken up the cause. In a matter of months, it was possible that Quint’s cage would be smashed, at least for everyone in Britain.
The prospect filled him with a kind of vertigo. He might have broken the laws at every opportunity, but they had still molded him. The cage might not have left him crippled, but he’d be lying to himself if he denied that he’d been stunted.
He said, “Is that what happened, in your past? I ended up in some … lifelong partnership?” As he spoke the words, his mouth went dry, and he was suddenly afraid that the answer would be yes. With Chris. The life he’d missed out on was a life of happiness with Chris.
“No.”
“Then … what?” he pleaded. “What did I do? How did I live?” He caught himself, suddenly self-conscious, but added, “You can’t blame me for being curious.”
Helen said gently, “You don’t want to know what you can’t change. All of that is part of your own causal past now, as much as it is of mine.”
“If it’s part of my own history,” Robert countered, “don’t I deserve to know it? This man wasn’t me, but he brought you to me.”
Helen considered this. “You accept that he was someone else? Not someone whose actions you’re responsible for?”
“Of course.”
She said, “There was a trial, in 1952. For ‘Gross Indecency contrary to Section 11 of the Criminal Amendment Act of 1885.’ He wasn’t imprisoned, but the court ordered hormone treatments.”
“Hormone treatments?” Robert laughed. “What – testosterone, to make him more of a man?”
“No, estrogen. Which in men reduces the sex drive. There are side-effects, of course. Gynecomastia, among other things.”
Robert felt physically sick. They’d chemically castrated him, with drugs that had made him sprout breasts. Of all the bizarre abuse to which he’d been subjected, nothing had been as horrifying as that.
Helen continued, “The treatment lasted six months, and the effects were all temporary. But two years later, he took his own life. It was never clear exactly why.”
Robert absorbed this in silence. He didn’t want to know anything more.
After a while, he said, “How do you bear it? Knowing that in some branch or other, every possible form of humiliation is being inflicted on someone?”
Helen said, “I don’t bear it. I change it. That’s why I’m here.”
Robert bowed his head. “I know. And I’m grateful that our histories collided. But … how many histories don’t?” He struggled to find an example, though it was almost too painful to contemplate; since their first conversation, it was a topic he’d deliberately pushed to the back of his mind. “There’s not just an unchangeable Auschwitz in each of our pasts, there are an astronomical number of others – along with an astronomical number of things that are even worse.”
Helen said bluntly, “That’s not true.”
“What?” Robert looked up at her, startled.
She walked to the blackboard and erased it. “Auschwitz has happened, for both of us, and no one I’m aware of has ever prevented it – but that doesn’t mean that nobody stops it, anywhere.” She began sketching a network of fine lines on the blackboard. “You and I are having this conversation in countless microhistories – sequences of events where various different things happen with subatomic particles throughout the universe – but that’s irrelevant to us, we can’t tell those strands apart, so we might as well treat them all as one history.” She pressed the chalk down hard to make a thick streak that covered everything she’d drawn. “The quantum decoherence people call this ‘coarse graining’. Summing over all these indistinguishable details is what gives rise to classical physics in the first place.
“Now, ‘the two of us’ would have first met in many perceivably different coarse-grained histories – and furthermore, you’ve since diverged by making different choices, and experiencing different external possibilities, after those events.” She sketched two intersecting ribbons of coarse-grained histories, and then showed each history diverging further.
“World War II and the Holocaust certainly happened in both of our pasts – but that’s no proof that the total is so vast that it might as well be infinite. Remember, what stops us successfully intervening is the fact that we’re reaching back to a point where some of the parallel interventions start to bite their own tail. So when we fail, it can’t be counted twice: it’s just confirming what we already know.”
Robert protested, “But what about all the
versions of ’30s Europe that don’t happen to lie in either your past or mine? Just because we have no direct evidence for a Holocaust in those branches, that hardly makes it unlikely.”
Helen said, “Not unlikely per se, without intervention. But not fixed in stone either. We’ll keep trying, refining the technology, until we can reach branches where there’s no overlap with our own past in the ’30s. And there must be other, separate ribbons of intervention that happen in histories we can never even know about.”
Robert was elated. He’d imagined himself clinging to a rock of improbable good fortune in an infinite sea of suffering – struggling to pretend, for the sake of his own sanity, that the rock was all there was. But what lay around him was not inevitably worse; it was merely unknown. In time, he might even play a part in ensuring that every last tragedy was not repeated across billions of worlds.
He reexamined the diagram. “Hang on. Intervention doesn’t end divergence, though, does it? You reached us, a year ago, but in at least some of the histories spreading out from that moment, won’t we still have suffered all kinds of disasters, and reacted in all kinds of self-defeating ways?”
“Yes,” Helen conceded, “but fewer than you might think. If you merely listed every sequence of events that superficially appeared to have a non-zero probability, you’d end up with a staggering catalog of absurdist tragedies. But when you calculate everything more carefully, and take account of Planck-scale effects, it turns out to be nowhere near as bad. There are no coarse-grained histories where boulders assemble themselves out of dust and rain from the sky, or everyone in London or Madras goes mad and slaughters their children. Most macroscopic systems end up being quite robust – people included. Across histories, the range of natural disasters, human stupidity, and sheer bad luck isn’t overwhelmingly greater than the range you’re aware of from this history alone.”
Robert laughed. “And that’s not bad enough?”
“Oh, it is. But that’s the best thing about the form I’ve taken.”
“I’m sorry?”
Helen tipped her head and regarded him with an expression of disappointment. “You know, you’re still not as quick on your feet as I’d expected.”
Robert’s face burned, but then he realized what he’d missed, and his resentment vanished.
“You don’t diverge? Your hardware is designed to end the process? Your environment, your surroundings, will still split you into different histories – but on a coarse-grained level, you don’t contribute to the process yourself?”
“That’s right.”
Robert was speechless. Even after a year, she could still toss him a hand grenade like this.
Helen said, “I can’t help living in many worlds; that’s beyond my control. But I do know that I’m one person. Faced with a choice that puts me on a knife-edge, I know I won’t split and take every path.”
Robert hugged himself, suddenly cold. “Like I do. Like I have. Like all of us poor creatures of flesh.”
Helen came and sat beside him. “Even that’s not irrevocable. Once you’ve taken this form – if that’s what you choose – you can meet your other selves, reverse some of the scatter. Give some a chance to undo what they’ve done.”
This time, Robert grasped her meaning at once. “Gather myself together? Make myself whole?”
Helen shrugged. “If it’s what you want. If you see it that way.”
He stared back at her, disoriented. Touching the bedrock of physics was one thing, but this possibility was too much to take in.
Someone knocked on the study door. The two of them exchanged wary glances, but it wasn’t Quint, back for more punishment. It was a porter bearing a telegram.
When the man had left, Robert opened the envelope.
“Bad news?” Helen asked.
He shook his head. “Not a death in the family, if that’s what you meant. It’s from John Hamilton. He’s challenging me to a debate. On the topic ‘Can A Machine Think?’”
“What, at some university function?”
“No. On the BBC. Four weeks from tomorrow.” He looked up. “Do you think I should do it?”
“Radio or television?”
Robert reread the message. “Television.”
Helen smiled. “Definitely. I’ll give you some tips.”
“On the subject?”
“No! That would be cheating.” She eyed him appraisingly. “You can start by throwing out your electric razor. Get rid of the permanent five o’clock shadow.”
Robert was hurt. “Some people find that quite attractive.”
Helen replied firmly, “Trust me on this.”
#
The BBC sent a car to take Robert down to London. Helen sat beside him in the back seat.
“Are you nervous?” she asked.
“Nothing that an hour of throwing up won’t cure.”
Hamilton had suggested a live broadcast, “to keep things interesting,” and the producer had agreed. Robert had never been on television; he’d taken part in a couple of radio discussions on the future of computing, back when the Mark I had first come into use, but even those had been taped.
Hamilton’s choice of topic had surprised him at first, but in retrospect it seemed quite shrewd. A debate on the proposition that “Modern Science is the Devil’s Work” would have brought howls of laughter from all but the most pious viewers, whereas the purely metaphorical claim that “Modern Science is a Faustian Pact” would have had the entire audience nodding sagely in agreement, while carrying no implications whatsoever. If you weren’t going to take the whole dire fairy tale literally, everything was “a Faustian Pact” in some sufficiently watered-down sense: everything had a potential downside, and this was as pointless to assert as it was easy to demonstrate.
Robert had met considerable incredulity, though, when he’d explained to journalists where his own research was leading. To date, the press had treated him as a kind of eccentric British Edison, churning out inventions of indisputable utility, and no one seemed to find it at all surprising or alarming that he was also, frankly, a bit of a loon. But Hamilton would have a chance to exploit, and reshape, that perception. If Robert insisted on defending his goal of creating machine intelligence, not as an amusing hobby that might have been chosen by a public relations firm to make him appear endearingly daft, but as both the ultimate vindication of materialist science and the logical endpoint of most of his life’s work, Hamilton could use a victory tonight to cast doubt on everything Robert had done, and everything he symbolized. By asking, not at all rhetorically, “Where will this all end?”, he was inviting Robert to step forward and hang himself with the answer.
The traffic was heavy for a Sunday evening, and they arrived at the Shepherd’s Bush studios with only fifteen minutes until the broadcast. Hamilton had been collected by a separate car, from his family home near Oxford. As they crossed the studio Robert spotted him, conversing intensely with a dark-haired young man.
He whispered to Helen, “Do you know who that is, with Hamilton?”
She followed his gaze, then smiled cryptically. Robert said, “What? Do you recognize him from somewhere?”
“Yes, but I’ll tell you later.”
As the make-up woman applied powder, Helen ran through her long list of rules again. “Don’t stare into the camera, or you’ll look like you’re peddling soap powder. But don’t avert your eyes. You don’t want to look shifty.”
The make-up woman whispered to Robert, “Everyone’s an expert.”
“Annoying, isn’t it?” he confided.
Michael Polanyi, an academic philosopher who was well-known to the public after presenting a series of radio talks, had agreed to moderate the debate. Polanyi popped into the make-up room, accompanied by the producer; they chatted with Robert for a couple of minutes, setting him at ease and reminding him of the procedure they’d be following.
They’d only just left him when the floor manager appeared. “We need you in the studio now, please, Pro
fessor.” Robert followed her, and Helen pursued him part of the way. “Breathe slowly and deeply,” she urged him.
“As if you’d know,” he snapped.
Robert shook hands with Hamilton then took his seat on one side of the podium. Hamilton’s young adviser had retreated into the shadows; Robert glanced back to see Helen watching from a similar position. It was like a duel: they both had seconds. The floor manager pointed out the studio monitor, and as Robert watched it was switched between the feeds from two cameras: a wide shot of the whole set, and a closer view of the podium, including the small blackboard on a stand beside it. He’d once asked Helen whether television had progressed to far greater levels of sophistication in her branch of the future, once the pioneering days were left behind, but the question had left her uncharacteristically tongue-tied.
The floor manager retreated behind the cameras, called for silence, then counted down from ten, mouthing the final numbers.
The broadcast began with an introduction from Polanyi: concise, witty, and non-partisan. Then Hamilton stepped up to the podium. Robert watched him directly while the wide-angle view was being transmitted, so as not to appear rude or distracted. He only turned to the monitor when he was no longer visible himself.
“Can a machine think?” Hamilton began. “My intuition tells me: no. My heart tells me: no. I’m sure that most of you feel the same way. But that’s not enough, is it? In this day and age, we aren’t allowed to rely on our hearts for anything. We need something scientific. We need some kind of proof.
“Some years ago, I took part in a debate at Oxford University. The issue then was not whether machines might behave like people, but whether people themselves might be mere machines. Materialists, you see, claim that we are all just a collection of purposeless atoms, colliding at random. Everything we do, everything we feel, everything we say, comes down to some sequence of events that might as well be the spinning of cogs, or the opening and closing of electrical relays.