Permutation City

by Greg Egan

  It rang so true that he hung his head in shame.

  Then he dropped the note, raised his head, and bellowed with all the strength in his non-existent lungs:

  “DURHAM! YOU PRICK!”

  #

  Paul thought about smashing furniture. Instead, he took a long, hot shower. In part, to calm himself; in part, as an act of petty vengeance: twenty virtual minutes of gratuitous hydrodynamic calculations would annoy the cheapskate no end. He scrutinized the droplets and rivulets of water on his skin, searching for some small but visible anomaly at the boundary between his body – computed down to subcellular resolution – and the rest of the simulation, which was modeled much more crudely. If there were any discrepancies, though, they were too subtle to detect.

  He dressed, and ate a late breakfast, shrugging off the surrender to normality. What was he meant to do? Go on a hunger strike? Walk around naked, smeared in excrement? He was ravenous, having fasted before the scan, and the kitchen was stocked with a – literally – inexhaustible supply of provisions. The muesli tasted exactly like muesli, the toast exactly like toast, but he knew there was a certain amount of cheating going on with both taste and aroma. The detailed effects of chewing, and the actions of saliva, were being faked from a patchwork of empirical rules, not generated from first principles; there were no individual molecules being dissolved from the food and torn apart by enzymes – just a rough set of evolving nutrient concentration values, associated with each microscopic “parcel” of saliva. Eventually, these would lead to plausible increases in the concentrations of amino acids, various carbohydrates, and other substances all the way down to humble sodium and chloride ions, in similar “parcels” of gastric juices … which in turn would act as input data to the models of his intestinal villus cells. From there, into the bloodstream.

  Urine and feces production were optional – some Copies wished to retain every possible aspect of corporeal life – but Paul had chosen to do without. (So much for smearing himself in excrement.) His bodily wastes would be magicked out of existence long before reaching bladder or bowel. Ignored out of existence; passively annihilated. All that it took to destroy something, here, was to fail to keep track of it.

  Coffee made him feel alert, but also slightly detached – as always. Neurons were modeled in the greatest detail, and whatever receptors to caffeine and its metabolites had been present on each individual neuron in his original’s brain at the time of the scan, his own model-of-a-brain incorporated every one of them – in a simplified, but functionally equivalent, form.

  And the physical reality behind it all? A cubic meter of silent, motionless optical crystal, configured as a cluster of over a billion individual processors, one of a few hundred identical units in a basement vault … somewhere on the planet. Paul didn’t even know what city he was in; the scan had been made in Sydney, but the model’s implementation would have been contracted out by the local node to the lowest bidder at the time.

  He took a sharp vegetable knife from the kitchen drawer, and made a shallow cut across his left forearm. He flicked a few drops of blood onto the sink – and wondered exactly which software was now responsible for the stuff. Would the blood cells “die off” slowly – or had they already been surrendered to the extrasomatic general-physics model, far too unsophisticated to represent them, let alone keep them “alive”?

  If he tried to slit his wrists, when exactly would Durham intervene? He gazed at his distorted reflection in the blade. Most likely, his original would let him die, and then run the whole model again from scratch, simply leaving out the knife. He’d re-run all the earlier Copies hundreds of times, tampering with various aspects of their surroundings, trying in vain to find some cheap trick, some distraction which would keep them from wanting to bale out. It was a measure of sheer stubbornness that it had taken him so long to admit defeat and rewrite the rules.

  Paul put down the knife. He didn’t want to perform that experiment. Not yet.

  #

  Outside his own apartment, everything was slightly less than convincing; the architecture of the building was reproduced faithfully enough, down to the ugly plastic pot-plants, but every corridor was deserted, and every door to every other apartment was sealed shut – concealing, literally, nothing. He kicked one door, as hard as he could; the wood seemed to give slightly, but when he examined the surface, the paint wasn’t even marked. The model would admit to no damage here, and the laws of physics could screw themselves.

  There were pedestrians and cyclists on the street – all purely recorded. They were solid rather than ghostly, but it was an eerie kind of solidity; unstoppable, unswayable, they were like infinitely strong, infinitely disinterested robots. Paul hitched a ride on one frail old woman’s back for a while; she carried him down the street, heedlessly. Her clothes, her skin, even her hair, all felt the same: hard as steel. Not cold, though. Neutral.

  The street wasn’t meant to serve as anything but three-dimensional wallpaper; when Copies interacted with each other, they often used cheap, recorded environments full of purely decorative crowds. Plazas, parks, open-air cafés; all very reassuring, no doubt, when you were fighting off a sense of isolation and claustrophobia. Copies could only receive realistic external visitors if they had friends or relatives willing to slow down their mental processes by a factor of seventeen. Most dutiful next-of-kin preferred to exchange video recordings. Who wanted to spend an afternoon with great-grandfather, when it burned up half a week of your life? Paul had tried calling Elizabeth on the terminal in his study – which should have granted him access to the outside world, via the computer’s communications links – but, not surprisingly, Durham had sabotaged that as well.

  When he reached the corner of the block, the visual illusion of the city continued, far into the distance, but when he tried to step forward onto the road, the concrete pavement under his feet started acting like a treadmill, sliding backward at precisely the rate needed to keep him motionless, whatever pace he adopted. He backed off and tried leaping over the affected region, but his horizontal velocity dissipated – without the slightest pretense of any “physical” justification – and he landed squarely in the middle of the treadmill.

  The people of the recording, of course, crossed the border with ease. One man walked straight at him; Paul stood his ground – and found himself pushed into a zone of increasing viscosity, the air around him becoming painfully unyielding, before he slipped free to one side.

  The sense that discovering a way to breach this barrier would somehow “liberate” him was compelling – but he knew it was absurd. Even if he did find a flaw in the program which enabled him to break through, he knew he’d gain nothing but decreasingly realistic surroundings. The recording could only contain complete information for points of view within a certain, finite zone; all there was to “escape to” was a region where his view of the city would be full of distortions and omissions, and would eventually fade to black.

  He stepped back from the corner, half dispirited, half amused. What had he hoped to find? A door at the edge of the model, marked EXIT, through which he could walk out into reality? Stairs leading metaphorically down to some boiler room representation of the underpinnings of this world, where he could throw a few switches and blow it all apart? He had no right to be dissatisfied with his surroundings; they were precisely what he’d ordered.

  What he’d ordered was also a perfect spring day. Paul closed his eyes and turned his face to the sun. In spite of everything, it was hard not to take solace from the warmth flooding onto his skin. He stretched the muscles in his arms, his shoulders, his back – and it felt like he was reaching out from the “self” in his virtual skull to all his mathematical flesh, imprinting the nebulous data with meaning; binding it all together, staking some kind of claim. He felt the stirrings of an erection. Existence was beginning to seduce him. He let himself surrender for a moment to a visceral sense of identity which drowned out all his pale mental images of optical processors, all
his abstract reflections on the software’s approximations and short-cuts. This body didn’t want to evaporate. This body didn’t want to bale out. It didn’t much care that there was another – “more real” – version of itself, elsewhere. It wanted to retain its wholeness. It wanted to endure.

  And if this was a travesty of life, there was always the chance of improvement. Maybe he could persuade Durham to restore his communications facilities; that would be a start. And when he grew bored with libraries, news systems, databases, and – if any of them would deign to meet him – the ghosts of the senile rich? He could always have himself suspended until processor speeds caught up with reality – when people would be able to visit without slow-down, and telepresence robots might actually be worth inhabiting.

  He opened his eyes, and shivered in the heat. He no longer knew what he wanted – the chance to bale out, to declare this bad dream over … or the possibility of virtual immortality – but he had to accept that there was only one way he could make the choice his own.

  He said quietly, “I won’t be your guinea pig. A collaborator, yes. An equal partner. If you want my cooperation, then you’re going to have to treat me like a colleague, not a … piece of apparatus. Understood?”

  A window opened up in front of him. He was shaken by the sight, not of his predictably smug twin, but of the room behind him. It was only his study – and he’d wandered through the virtual equivalent, unimpressed, just minutes before – but this was still his first glimpse of the real world, in real time. He moved closer to the window, in the hope of seeing if there was anyone else in the room – Elizabeth? – but the image was two-dimensional, the perspective remained unchanged as he approached.

  The flesh-and-blood Durham emitted a brief, high-pitched squeak, then waited with visible impatience while a second, smaller window gave Paul a slowed-down replay, four octaves lower:

  “Of course that’s understood! We’re collaborators. That’s exactly right. Equals. I wouldn’t have it any other way. We both want the same things out of this, don’t we? We both need answers to the same questions.”

  Paul was already having second thoughts. “Perhaps.”

  But Durham wasn’t interested in his qualms.

  Squeak. “You know we do! We’ve waited ten years for this … and now it’s finally going to happen. And we can begin whenever you’re ready.”

  PART ONE

  THE GARDEN-OF-EDEN CONFIGURATION

  Chapter 1

  (Remit not paucity)

  November 2050

  Maria Deluca had ridden past the stinking hole in Pyrmont Bridge Road for six days running, certain each time, as she’d approached, that she’d be greeted by the reassuring sight of a work team putting things right. She knew that there was no money for road works or drainage repairs this year, but a burst sewage main was a serious health risk; she couldn’t believe it would be neglected for long.

  On the seventh day, the stench was so bad from half a kilometer away that she turned into a side street, determined to find a detour.

  This end of Pyrmont was a depressing sight; not every warehouse was empty, not every factory abandoned, but they all displayed the same neglected look, the same peeling paint and crumbling brickwork. Half a dozen blocks west, she turned again – to be confronted by a vista of lavish gardens, marble statues, fountains and olive groves, stretching into the distance beneath a cloudless azure sky.

  Maria accelerated without thinking – for a few seconds, almost believing that she’d chanced upon a park of some kind, an impossibly well-kept secret in this decaying corner of the city. Then, as the illusion collapsed – punctured by sheer implausibility as much as any visible flaw – she pedaled on willfully, as if hoping to blur the imperfections and contradictions out of existence. She braked just in time, mounting the narrow footpath at the end of the cul-de-sac, the front wheel of her cycle coming to a halt centimeters from the warehouse wall.

  Close up, the mural was unimpressive, the brushstrokes clearly visible, the perspective obviously false. Maria backed away – and she didn’t have to retreat far to see why she’d been fooled. At a distance of twenty meters or so, the painted sky suddenly seemed to merge with the real thing; with a conscious effort, she could make the border reappear, but it was hard work keeping the slight difference in hue from being smoothed out of existence before her eyes – as if some subsystem deep in her visual cortex had shrugged off the unlikely notion of a sky-blue wall, and was actively collaborating in the deception. Further back, the grass and statues began to lose their two-dimensional, painted look – and at the corner where she’d turned into the cul-de-sac, every element of the composition fell into place, the mural’s central avenue now apparently converging toward the very same vanishing point as the interrupted road.

  Having found the perfect viewing position, she stood there awhile, propping up her cycle. Sweat on the back of her neck cooled in the faint breeze, then the morning sun began to bite. The vision was entrancing – and it was heartening to think that the local artists had gone to so much trouble to relieve the monotony of the neighborhood. At the same time, Maria couldn’t help feeling cheated. She didn’t mind having been taken in, briefly; what she resented was not being able to be fooled again. She could stand there admiring the artistry of the illusion for as long as she liked, but nothing could bring back the surge of elation she’d felt when she’d been deceived.

  She turned away.

  #

  Home, Maria unpacked the day’s food, then lifted her cycle and hooked it into its frame on the living room ceiling. The terrace house, one hundred and forty years old, was shaped like a cereal box: two stories high, but scarcely wide enough for a staircase. It had originally been part of a row of eight; four on one side had been gutted and remodeled into offices for a firm of architects; the other three had been demolished at the turn of the century to make way for a road that had never been built. The lone survivor was now untouchable under some bizarre piece of heritage legislation, and Maria had bought it for a quarter of the price of the cheapest modern flats. She liked the odd proportions – and with more space, she was certain, she would have felt less in control. She had as clear a mental image of the layout and contents of the house as she had of her own body, and she couldn’t recall ever misplacing even the smallest object. She couldn’t have shared the place with anyone, but having it to herself seemed to strike the right balance between her territorial and organizational needs. Besides, she believed that houses were meant to be thought of as vehicles – physically fixed, but logically mobile – and compared to a one-person space capsule or submarine, the size was more than generous.

  Upstairs, in the bedroom that doubled as an office, Maria switched on her terminal and glanced at a summary of the twenty-one items of mail which had arrived since she’d last checked. All were classified as “Junk”; there was nothing from anyone she knew – and nothing remotely like an offer of paid work. Camel’s Eye, her screening software, had identified six pleas for donations from charities (all worthy causes, but Maria hardened her heart); five invitations to enter lotteries and competitions; seven retail catalogs (all of which boasted that they’d been tailored to her personality and “current lifestyle requirements” – but Camel’s Eye had assessed their contents and found nothing of interest); and three interactives.

  The “dumb” audio-visual mail was all in standard, transparent data formats, but interactives were executable programs, machine code with heavily encrypted data, intentionally designed to be easier for a human to talk to than for screening software to examine and summarize. Camel’s Eye had run all three interactives (on a doubly-quarantined virtual machine – a simulation of a computer running a simulation of a computer) and tried to fool them into thinking that they were making their pitch to the real Maria Deluca. Two sales programs – superannuation and health insurance – had fallen for it, but the third had somehow deduced its true environment, and clammed up before disclosing anything. In theory, it was possible
for Camel’s Eye to analyze the program and figure out exactly what it would have said if it had been fooled; in practice, that could take weeks. The choice came down to trashing it blind, or talking to it in person.

  Maria ran the interactive. A man’s face appeared on the terminal; “he” met her gaze and smiled warmly, and she suddenly realized that “he” bore a slight resemblance to Aden. Close enough to elicit a flicker of recognition which the mask of herself she’d set up for Camel’s Eye would not have exhibited? Maria felt a mixture of annoyance and grudging admiration. She’d never shared an address with Aden – but no doubt the data analysis agencies correlated credit card use in restaurants, or whatever, to pick up relationships which didn’t involve cohabitation. Mapping useful connections between consumers had been going on for decades – but employing the data in this way, as a reality test, was a new twist.

  The junk mail, now rightly convinced that it was talking to a human being, began the spiel it had refused to waste on her digital proxy. “Maria, I know your time is valuable, but I hope you can spare a few seconds to hear me out.” It paused for a moment, to make her feel that her silence was some kind of assent. “I also know that you’re a highly intelligent, discerning woman, with no interest whatsoever in the muddled, irrational superstitions of the past, the fairy tales that comforted humanity in its infancy.” Maria guessed what was coming next; the interactive saw it on her face – she hadn’t bothered to hide behind any kind of filter – and it rushed to get a hook in. “No truly intelligent person, though, ever dismisses an idea without taking the trouble to evaluate it – skeptically, but fairly – and here at the Church of the God Who Makes No Difference—”

  Maria pointed two fingers at the interactive, and it died. She wondered if it was her mother who’d set the Church onto her, but that was unlikely. They must have targeted their new member’s family, automatically; if consulted, Francesca would have told them that they’d be wasting their time.