Permutation City

by Greg Egan

  “You could still be more selective.”

  “What did you have in mind? Something socially useful? Famine relief work? Counseling the dying? Or something intellectually challenging? Uncovering the fundamental laws of the universe? I have to admit that the TVC rules have slipped my mind completely; it might take me all of five seconds to look them up again. Searching for God? That’s a difficult one: Paul Durham never returns my calls. Self discovery—?”

  “You don’t have to leave yourself open to every conceivable absurdity.”

  “If I limited the range of options, I’d be repeating myself in no time at all. And if you find the phase I’m passing through so unbearable, you can always make it vanish: you can freeze yourself until I change.”

  Kate was indignant. “I have other time frames to worry about besides yours!”

  “The Elysians aren’t going anywhere.” He didn’t add that he knew she’d frozen herself half a dozen times already. Each time for a few more years than the time before.

  She turned toward him, parting her hair to show one baleful eye. “You’re fooling yourself, you know. You’re going to repeat yourself, eventually. However desperately you reprogram yourself, in the end you’re going to come full circle, and find that you’ve done it all before.”

  Peer laughed indulgently, and shouted, “We’ve certainly been through all this before – and you know that’s not true. It’s always possible to synthesize something new: a novel art form, a new field of study. A new esthetic, a new obsession.” Falling through the cool late afternoon air beside her was exhilarating, but he was already missing the smell of wood dust.

  Kate rendered the air around them motionless and silent, although they continued to descend. She released his hand, and said, “I know we’ve been through this before. I remember what you said last time: If the worst comes to the worst, for the first hundred years you can contemplate the number one. For the second hundred years you can contemplate the number two. And so on, ad infinitum. Whenever the numbers grow too big to hold in your mind, you can always expand your mind to fit them. QED. You’ll never run out of new and exciting interests.”

  Peer said gently, “Where’s your sense of humor? It’s a simple proof that the worst-case scenario is still infinite. I never suggested actually doing that.”

  “But you might as well.” Now that her face was no longer concealed, she looked more forlorn than angry – by choice, if not necessarily by artifice. “Why do you have to find everything so … fulfilling? Why can’t you discriminate? Why can’t you let yourself grow bored with things – then move on? Pick them up again later if you feel the urge.”

  “Sounds awfully quaint to me. Very human.”

  “It did work for them. Sometimes.”

  “Yes. And I’m sure it works for you, sometimes. You drift back and forth between your art, and watching the great Elysian soap opera. With a decade or two of aimless depression in between. You’re dissatisfied most of the time – and letting that happen is a conscious choice, as deliberate, and arbitrary, as anything I impose on myself. If that’s how you want to live, I’m not going to try to change you. But you can’t expect me to live the same way.”

  She didn’t reply. After a moment, the bubble of still air around them blew away, and the roar of the wind drowned the silence again.

  Sometimes he wondered if Kate had ever really come to terms with the shock of discovering that stowing away had granted them, not a few hundred years in a billionaires’ sanctuary, but a descent into the abyss of immortality. The Copy who had persuaded David Hawthorne to turn his back on the physical world; the committed follower – even before her death – of the Solipsist Nation philosophy; the woman who had needed no brain rewiring or elaborate external contrivances to accept her software incarnation … now acted more and more like a flesh-and-blood-wannabe – or rather, Elysian-wannabe – year by year. And there was no need for it. Their tiny slice of infinity was as infinite as the whole; ultimately, there was nothing the Elysians could do that Kate couldn’t.

  Except walk among them as an equal, and that was what she seemed to covet the most.

  True, the Elysians had deliberately set out to achieve the logical endpoint of everything she’d ever believed Copies should be striving for – while she’d merely hitched a ride by mistake. Their world would “always” (Elysian instant compared to Elysian instant) be bigger and faster than her own. So “naturally” – according to archaic human values which she hadn’t had the sense to erase – she wanted to be part of the main game. But Peer still found it absurd that she spent her life envying them, when she could have generated – or even launched – her own, equally complex, equally populous society, and turned her back on the Elysians as thoroughly as they’d turned their back on Earth.

  It was her choice. Peer took it in his stride, along with all their other disagreements. If they were going to spend eternity together, he believed they’d resolve their problems eventually – if they could be resolved at all. It was early days yet. As it always would be.

  He rolled over and looked down at the City – or the strange recursive map of the City which they made do with, buried as they were in the walls and foundations of the real thing. Malcolm Carter’s secret parasitic software wasn’t blind to its host; they could spy on what was going on in the higher levels of the program which surreptitiously ran them, even though they couldn’t affect anything which happened there. They could snatch brief, partial recordings of activity in the real City, and play them back in a limited duplicate environment. It was a bit like … being the widely-separated letters in the text of Ulysses which read: Peer and Kate read, “Leopold Bloom wandered through Dublin.” If not quite so crude an abridgment.

  Certainly, the view from the air was still breathtaking; Peer had to concede that it was probably indistinguishable from the real thing. The sun was setting over the ocean as they descended, and the Ulam Falls glistened in the east like a sheet of amber set in the granite face of Mount Vine. In the foothills, a dozen silver needles and obsidian prisms, fanciful watchtowers, caught the light and scattered it between them. Peer followed the river down, through lush tropical forests, across dark plains of grassland, into the City itself.

  The buildings on the outskirts were low and sprawling, becoming gradually taller and narrower; the profile swept up in a curve which echoed the shape of Mount Vine. Closer to the center, a thousand crystalline walkways linked the City’s towers at every level, connections so dense and stellated as to make it seem possible that every building was joined, directly, to all the rest. That wasn’t true – but the sense that it might have been was still compelling.

  Decorative crowds filled the streets and walkways: mindless puppets obeying the simplest rules, but looking as purposeful and busy as any human throng. A strange adornment, perhaps – but not much stranger than having buildings and streets at all. Most Elysians merely visited this place, but last time Peer had concerned himself with such things, a few hundred of them – mainly third-generation – had taken up inhabiting the City full-time: adopting every detail of its architecture and geography as fixed parameters, swearing fidelity to its Euclidean distances. Others – mainly first-generation – had been appalled by the behavior of this sect. It was strange how “reversion” was the greatest taboo amongst the oldest Elysians, who were so conservative in most other ways. Maybe they were afraid of becoming homesick.

  Kate said, “Town Hall.”

  He followed her down through the darkening air. The City always smelled sweet to Peer; sweet but artificial, like a newly unwrapped electronic toy, all microchips and plastic, from David Hawthorne’s childhood. They spiraled around the central golden tower, the City’s tallest, weaving their way between the transparent walkways. Playing Peter Pan and Tinker Bell. Peer had long ago given up arguing with Kate about the elaborate routes she chose for entering the reconstruction; she ran this peephole on the City out of her own time, and she controlled access to the environment completely. He
could either put up with her rules, or stay away altogether. And the whole point of being here was to please her.

  They alighted on the paved square outside the Town Hall’s main entrance. Peer was startled to recognize one of the fountains as a scaled-up version of Malcolm Carter’s demonstration for his algorithmic piggy-back tricks: a cherub wrestling a snake. He must have noticed it before – he’d stood on this spot a hundred times – but if so, he’d forgotten. His memory was due for maintenance; it was a while since he’d increased the size of the relevant networks, and they were probably close to saturation. Simply adding new neurons slowed down recall – relative to other brain functions – making some modes of thought seem like swimming through molasses; a whole host of further adjustments were necessary to make the timing feel right. The Elysians had written software to automate this tuning process, but he disliked the results of the versions they’d shared with each other (and hence made accessible to him), so he’d written his own – but he’d yet to perfect it. Things like table legs kept getting in the way.

  The square wasn’t empty, but the people around them all looked like puppets, merely strolling past. The City’s owners were already inside – and so Kate’s software, which spied on the true City and reconstructed it for the two of them, was carrying most of the burden of computing the appearance of their surroundings, now officially unobserved. He took Kate’s hand – and she allowed it, though she made her skin feel as cold as marble – and they walked into the hall.

  The cavernous room was about half-full, so some eight thousand Elysians had turned up for the meeting. Peer granted himself a brief bird’s-eye view of the crowd. A variety of fashions in clothing – or lack of it – and body type were represented, certainly spanning the generations, but most people had chosen to present in more-or-less traditional human form. The exceptions stood out. One clique of fourth-generation Elysians displayed themselves as modified Babbage engines; the entire hall couldn’t have held one of them “to scale”, so portions of the mechanism poked through into their seating allocation from some hidden dimension. Ditto for those who’d turned up as “Searle’s Chinese Rooms”: huge troupes of individual humans (or human-shaped automatons), each carrying out a few simple tasks, which together amounted to a complete working computer. The “components” seated in the hall were Kali-armed blurs, gesticulating at invisible colleagues with coded hand movements so rapid that they seemed to merge into a static multiple exposure. Peer had no idea how either type of system collected sound and vision from its surroundings to feed to the perfectly normal Elysians these unwieldy computers were (presumably) simulating, as the end result of all their spinning cogs and frantic hand movements – or whether the people in question experienced anything much different than they would have if they’d simply shown that standard physiological model to the world. Pretentious fancy dress aside, there were a smattering of animal bodies visible – which may or may not have reflected their inhabitants’ true models. It could be remarkably comfortable being a lion, or even a snake – if your brain had been suitably adapted for the change. Peer had spent some time inhabiting the bodies of animals, both historical and mythical, and he’d enjoyed them all – but when the phase was over, he’d found that with very little rewiring, he could make the human form feel every bit as good. It seemed more elegant to be comfortable with his ancestral physiology. The majority of Elysians apparently agreed.

  Eight thousand was a typical attendance figure – but Peer could not have said what fraction of the total population it represented. Even leaving out Callas, Shaw and Riemann – the three founders who’d remained in their own private worlds, never making contact with anyone – there might have been hundreds or thousands of members of the later generations who’d opted out of the core community without ever announcing their existence.

  The ever-expanding cube of Elysium had been divided up from the outset into twenty-four ever-expanding oblique pyramids; one for each of the eighteen founders and their offspring, and six for common ventures (such as Permutation City itself – but mostly Planet Lambert). Most Elysians – or at least, most who used the City – had chosen to synch themselves to a common time rate. This Standard Time grew steadily faster against Absolute Time – the ticking of the TVC cellular automaton’s clock – so every Elysian needed a constantly growing allocation of processors to keep up – but Elysium itself was growing even faster, leaving everyone with an ever-larger surplus of computing power.

  Each founder’s territory was autonomous, subdivided on his or her own terms. By now, each one could have supported a population of several trillion, living by Standard Time. But Peer suspected that most of the processors were left idle – and he had occasionally daydreamed about some fifth-generation Elysian studying the City’s history, getting a curious hunch about Malcolm Carter, and brow-beating one of the founders into supplying the spare computing resources of a near-empty pyramid to scan the City for stowaways. All of Carter’s ingenious camouflage – and the atom-in-a-haystack odds which had been their real guarantee against discovery – would count for nothing under such scrutiny, and once their presence was identified, they could easily be disinterred … assuming that the Elysians were generous enough to do that for a couple of petty thieves.

  Kate claimed to believe that this was inevitable, in the long term. Peer didn’t much care if they were found or not; all that really mattered to him was the fact that the City’s computational infrastructure was also constantly expanding, to enable it to keep up with both the growing population, and the ever-increasing demands of Elysian Standard Time. As long as that continued, his own tiny fraction of those resources also steadily increased. Immortality would have been meaningless, trapped in a “machine” with a finite number of possible states; in a finite time he would have exhausted the list of every possible thing he could be. Only the promise of eternal growth made sense of eternal life.

  Kate had timed their entrance into the replay perfectly. As they settled into empty seats near the back of the hall, Paul Durham himself took the stage.

  He said, “Thank you for joining me. I’ve convened this meeting to discuss an important proposal concerning Planet Lambert.”

  Peer groaned. “I could be making table legs, and you’ve dragged me along to Attack of the Killer Bees. Part One Thousand and Ninety-Three.”

  Kate said, “You could always choose to be glad you’re here. There’s no need to be dissatisfied.”

  Peer shut up, and Durham – frozen by the interruption – continued. “As most of you will know, the Lambertians have been making steady progress recently in the scientific treatment of their cosmology. A number of teams of theorists have proposed dust-and-gas-cloud models for the formation of their planetary system – models which come very close to the truth. Although no such process ever literally took place in the Autoverse, it was crudely simulated before the launch, to help design a plausible ready-made system. The Lambertians are now zeroing in on the parameters of that simulation.” He gestured at a giant screen behind him, and vision appeared: several thousand of the insect-like Lambertians swarming in the air above a lush blue-green meadow.

  Peer was disappointed. Scientific treatment of their cosmology sounded like the work of a technologically sophisticated culture, but there were no artifacts visible in the scene: no buildings, no machines, not even the simplest tools. He froze the image and expanded a portion of it. The creatures themselves looked exactly the same to him as they’d looked several hundred thousand Lambertian years before, when they’d been singled out as the Species Most Likely To Give Rise to Civilization. Their segmented, chitinous bodies were still naked and unadorned. What had he expected? Insects in lab coats? No – but it was still hard to accept that the leaps they’d made in intelligence had left no mark on their appearance, or their surroundings.

  Durham said, “They’re communicating a version of the theory, and actively demonstrating the underlying mathematics at the same time; like one group of researchers sending a c
omputer model to another – but the Lambertians don’t have artificial computers. If the dance looks valid it’s taken up by other groups – and if they sustain it long enough, they’ll internalize the pattern: they’ll be able to remember it without continuing to perform it.”

  Peer whispered, “Come back to the workshop and dance cosmological models with me?” Kate ignored him.

  “The dominant theory employs accurate knowledge of Autoverse chemistry and physics, and includes a detailed breakdown of the composition of the primordial cloud. It goes no further. As yet, there’s no hypothesis about the way in which that particular cloud might have come into existence; no explanation for the origin and relative abundances of the elements. And there can be no explanation, no sensible prior history; the Autoverse doesn’t provide one. No Big Bang: General Relativity doesn’t apply, their space-time is flat, their universe isn’t expanding. No elements formed in stars: there are no nuclear forces, no fusion; stars burn by gravity alone – and their sun is the only star.

  “So, these cosmologists are about to hit a brick wall – through no fault of their own. Dominic Repetto has suggested that now would be the ideal time for us to make contact with the Lambertians. To announce our presence. To explain their planet’s origins. To begin a carefully moderated cultural exchange.”

  A soft murmuring broke out among the crowd. Peer turned to Kate. “This is it? This is the news I couldn’t miss?”

  She stared back at him, pityingly. “They’re talking about first contact with an alien race. Did you really want to sleep-walk right through that?”

  Peer laughed. “First contact? They’ve observed these insects in microscopic detail since the days they were single-celled algae. Everything about them is known already: their biology, their language, their culture. It’s all in the central library. These ‘aliens’ have evolved on a microscope slide. There are no surprises in store.”