# Permutation City

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Paul Durham keeps making Copies of himself: software simulations of his own brain and body which can be run in virtual reality, albeit seventeen times more slowly than real time. He wants them to be his guinea pigs for a set of experiments about the nature of artificial intelligence, time, and causality, but they keep changing their mind and baling out on him, shutting themselves down.

Maria Deluca is an Autoverse addict; she's unemployed and running out of money, but she can't stop wasting her time playing around with the cellular automaton known as the Autoverse, a virtual world that follows a simple set of mathematical rules as its 'laws of physics'.

Paul makes Maria a very strange offer: he asks her to design a seed for an entire virtual biosphere able to exist inside the Autoverse, modelled right down to the molecular level. The job will pay well, and will allow her to indulge her obsession. There has to be a catch, though, because such a seed would be useless without a simulation of the Autoverse large enough to allow the resulting biosphere to grow and flourish-a feat far beyond the capacity of all the computers in the world.

Permutation City won the John W. Campbell Award for the best science-fiction novel of the year in 1995 and was nominated for the Philip K. Dick Award that same year. 1994 en


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Permutation City


Millennium/Orion Publishing Group


London 1994 1-85798-174-X


Greg Egan

PERMUTATION CITY


Into a mute crypt, I Can't pity our time Turn amity poetic Ciao, tiny trumpet! Manic piety tutor Tame purity tonic Up, meiotic tyrant! I taint my top cure To it, my true panic Put at my nice riot To trace impunity I tempt an outcry, I Pin my taut erotic Art to epic mutiny Can't you permit it To cite my apt ruin? My true icon: tap it Copy time, turn it; a Rite to cut my pain Atomic putty? Rien!


Found in the memory of a discarded notepad in the Common Room of the Psychiatric Ward, Blacktown Hospital, June 6, 2045.

STREET SCENE

There were cyclists and pedestrians on the street-all 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.

When Paul reached the corner, the visual illusion of the city continued off into the distance; but when he tried to step forward, the concrete pavement under his feet started sliding backward, like a treadmill.

He was on the edge of his universe.

PROLOGUE

(Rip, tie, cut toy man)

JUNE 2045

Paul Durham opened his eyes, blinking at the room's unexpected brightness, then lazily reached out to place one hand in a patch of sunlight at the edge of the bed. Dust motes drifted across the shaft of light which slanted down from a gap between the curtains, each speck appearing for all the world to be conjured into, and out of, existence-evoking a childhood memory of the last time he'd found this illusion so compelling, so hypnotic: He stood in the kitchen doorway, afternoon light slicing the room; dust, flour and steam swirling in the plane of bright air. For one sleep-addled moment, still trying to wake, to collect himself, to order his life, it seemed to make as much sense to place these two fragments side by side-watching sunlit dust motes, forty years apart-as it did to follow the ordinary flow of time from one instant to the next. Then he woke a little more, and the confusion passed.

Paul felt utterly refreshed-and utterly disinclined to give up his present state of comfort. He couldn't think why he'd slept so late, but he didn't much care. He spread his fingers on the sun-warmed sheet, and thought about drifting back to sleep.

He closed his eyes and let his mind grow blank-and then caught himself, suddenly uneasy, without knowing why. He'd done something foolish, something insane, something he was going to regret, badly... but the details remained elusive, and he began to suspect that it was nothing more than the lingering mood of a dream. He tried to recall exactly what he'd dreamed, without much hope; unless he was catapulted awake by a nightmare, his dreams were usually evanescent. And yet-

He leaped out of bed and crouched down on the carpet, fists to his eyes, face against his knees, lips moving soundlessly. The shock of realization was a palpable thing: a red lesion behind his eyes, pulsing with blood... like the aftermath of a hammer blow to the thumb-and tinged with the very same mixture of surprise, anger, humiliation and idiot bewilderment. Another childhood memory: He held a nail to the wood, yes-but only to camouflage his true intentions. He'd seen his father injure himself this way-but he knew that he needed first-hand experience to understand the mystery of pain. And he was sure that it would be worth it, right up to the moment when he swung the hammer down-

He rocked back and forth, on the verge of laughter, trying to keep his mind blank, waiting for the panic to subside. And eventually, it did-to be replaced by one simple, perfectly coherent thought: I don't want to be here.

What he'd done to himself was insane-and it had to be undone, as swiftly and painlessly as possible. How could he have ever imagined reaching any other conclusion?

Then he began to remember the details of his preparations. He'd anticipated feeling this way. He'd planned for it. However bad he felt, it was all part of the expected progression of responses. Panic. Regret. Analysis. Acceptance.

Two out of four; so far, so good.

Paul uncovered his eyes, and looked around the room. Away from a few dazzling patches of direct sunshine, everything glowed softly in the diffuse light: the matte white brick walls, the imitation (imitation) mahogany furniture; even the posters-Bosch, Dali, Ernst, and Giger-looked harmless, domesticated. Wherever he turned his gaze (if nowhere else), the simulation was utterly convincing; the spotlight of his attention made it so. Hypothetical light rays were being traced backward from individual rod and cone cells on his simulated retinas, and projected out into the virtual environment to determine exactly what needed to be computed: a lot of detail near the center of his vision, much less toward the periphery. Objects out of sight didn't 'vanish' entirely, if they influenced the ambient light, but Paul knew that the calculations would rarely be pursued beyond the crudest first-order approximations: Bosch's Garden of Earthly Delights reduced to an average reflectance value, a single gray rectangle-because once his back was turned, any more detail would have been wasted. Everything in the room was as finely resolved, at any given moment, as it needed to be to fool him-no more, no less.

He had been aware of the technique for decades. It was something else to experience it. He resisted the urge to wheel around suddenly, in a futile attempt to catch the process out-but for a moment it was almost unbearable, just knowing what was happening at the edge of his vision. The fact that his view of the room remained flawless only made it worse, an irrefutable paranoid fixation: No matter how fast you turn your head, you'll never even catch a glimpse of what's going on all around you...

He closed his eyes again for a few seconds. When he opened them, the feeling was already less oppressive. No doubt it would pass; it seemed too bizarre a state of mind to be sustained for long. Certainly, none of the other Copies had reported anything similar... but then, none of them had volunteered much useful data at all. They'd just ranted abuse, whined about their plight, and then terminated themselves-all within fifteen (subjective) minutes of gaining consciousness.

And this one? How was he different from Copy number four? Three years older. More stubborn? More determined? More desperate for success? He'd believed so. If he hadn't felt more committed than ever-if he hadn't been convinced that he was, finally, prepared to see the whole thing through-he would never have gone ahead with the scan.

But now that he was 'no longer' the flesh-and-blood Paul Durham-'no longer' the one who'd sit outside and watch the whole experiment from a safe distance-all of that determination seemed to have evaporated.

Suddenly he wondered: What makes me so sure that I'm not still flesh and blood? He laughed weakly, hardly daring to take the possibility seriously. His most recent memories seemed to be of lying on a trolley in the Landau Clinic, while technicians prepared him for the scan-on the face of it, a bad sign-but he'd been overwrought, and he'd spent so long psyching himself up for 'this,' that perhaps he'd forgotten coming home, still hazy from the anesthetic, crashing into bed, dreaming...

He muttered the password, 'Abulafia'-and his last faint hope vanished, as a black-on-white square about a meter wide, covered in icons, appeared in midair in front of him.

He gave the interface window an angry thump; it resisted him as if it was solid, and firmly anchored. As if he was solid, too. He didn't really need any more convincing, but he gripped the top edge and lifted himself off the floor. He instantly regretted this; the realistic cluster of effects of exertion-down to the plausible twinge in his right elbow-pinned him to this 'body,' anchored him to this 'place,' in exactly the way he knew he should be doing everything he could to avoid.

He lowered himself to the floor with a grunt. He was the Copy. Whatever his inherited memories told him, he was 'no longer' human; he would never inhabit his real body 'again.' Never inhabit the real world again... unless his cheapskate original scraped up the money for a telepresence robot-in which case he could spend his time blundering around in a daze, trying to make sense of the lightning-fast blur of human activity. His model-of-a-brain ran seventeen times slower than the real thing. Yeah, sure, if he hung around, the technology would catch up, eventually-and seventeen times faster for him than for his original. And in the meantime? He'd rot in this prison, jumping through hoops, carrying out Durham's precious research-while the man lived in his apartment, spent his money, slept with Elizabeth...

Paul leant against the cool surface of the interface, dizzy and confused. Whose precious research? He'd wanted this so badly-and he'd done this to himself with his eyes wide open. Nobody had forced him, nobody had deceived him. He'd known exactly what the drawbacks would be-but he'd hoped that he would have the strength of will (this time, at last) to transcend them: to devote himself, monk-like, to the purpose for which he'd been brought into being, content in the knowledge that his other self was as unconstrained as ever.

Looking back, that hope seemed ludicrous. Yes, he'd made the decision freely-for the fifth time-but it was mercilessly clear, now, that he'd never really faced up to the consequences. All the time he'd spent, supposedly 'preparing himself' to be a Copy, his greatest source of resolve had been to focus on the outlook for the man who'd remain flesh and blood. He'd told himself that he was rehearsing 'making do with vicarious freedom'-and no doubt he had been genuinely struggling to do just that... but he'd also been taking secret comfort in the knowledge that he would 'remain' on the outside-that his future, then, still included a version with absolutely nothing to fear.

And as long as he'd clung to that happy truth, he'd never really swallowed the fate of the Copy at all.

People reacted badly to waking up as Copies. Paul knew the statistics. Ninety-eight percent of Copies made were of the very old, and the terminally ill. People for whom it was the last resort-most of whom had spent millions beforehand, exhausting all the traditional medical options; some of whom had even died between the taking of the scan and the time the Copy itself was run. Despite this, fifteen percent decided on awakening-usually in a matter of hours-that they couldn't face living this way.

And of those who were young and healthy, those who were merely curious, those who knew they had a perfectly viable, living, breathing body outside?

The bale-out rate so far had been one hundred percent.

Paul stood in the middle of the room, swearing softly for several minutes, acutely aware of the passage of time. He didn't feel ready-but the longer the other Copies had waited, the more traumatic they seemed to have found the decision. He stared at the floating interface; its dreamlike, hallucinatory quality helped, slightly. He rarely remembered his dreams, and he wouldn't remember this one-but there was no tragedy in that.

He suddenly realized that he was still stark naked. Habit-if no conceivable propriety-nagged at him to put on some clothes, but he resisted the urge. One or two perfectly innocent, perfectly ordinary actions like that, and he'd find he was taking himself seriously, thinking of himself as real, making it even harder...

He paced the bedroom, grasped the cool metal of the doorknob a couple of times, but managed to keep himself from turning it. There was no point even starting to explore this world.

He couldn't resist peeking out the window, though. The view of north Sydney was flawless; every building, every cyclist, every tree, was utterly convincing-but that was no great feat; it was a recording, not a simulation. Essentially photographic-give or take some computerized touching up and filling in-and totally predetermined. To cut costs even further, only a tiny part of it was 'physically' accessible to him; he could see the harbor in the distance, but he knew that if he tried to go for a stroll down to the water's edge...

Enough. Just get it over with.

Paul turned back to the interface and touched a menu icon labelled utilities; it spawned another window in front of the first. The function he was seeking was buried several menus deep-but he knew exactly where to look for it. He'd watched this, from the outside, too many times to have forgotten.

He finally reached the emergencies menu-which included a cheerful icon of a cartoon figure suspended from a parachute. Baling out was what everyone called it-but he didn't find that too cloyingly euphemistic; after all, he could hardly commit 'suicide' when he wasn't legally human. The fact that a bale-out option was compulsory had nothing to do with anything so troublesome as the 'rights' of the Copy; the requirement arose solely from the ratification of certain, purely technical, international software standards.

Paul prodded the icon; it came to life, and recited a warning spiel. He scarcely paid attention. Then it said, 'Are you absolutely sure that you wish to shut down this Copy of Paul Durham?'

Nothing to it. Program A asks Program B to confirm its request for orderly termination. Packets of data are exchanged.

'Yes, I'm sure.'

A metal box, painted red, appeared at his feet. He opened it, took out the parachute, strapped it on.

Then he closed his eyes and said, 'Listen to me. Just listen! How many times do you need to be told? I'll skip the personal angst; you've heard it all before-and ignored it all before. It doesn't matter how I feel. But... when are you going to stop wasting your time, your money, your energy-when are you going to stop wasting your life-on something which you just don't have the strength to carry through?'

Paul hesitated, trying to put himself in the place of his original, hearing those words-and almost wept with frustration. He still didn't know what he could say that would make a difference. He'd shrugged off the testimony of all the earlier Copies himself; he'd never been able to accept their claims to know his own mind better than he did. Just because they'd lost their nerve and chosen to bale out, who were they to proclaim that he'd never give rise to a Copy who'd choose otherwise? All he had to do was strengthen his resolve, and try again...

He shook his head. 'It's been ten years, and nothing's changed. What's wrong with you? Do you honestly still believe that you're brave enough-or crazy enough-to be your own guinea pig? Do you?'

He paused again, but only for a moment; he didn't expect a reply.

He'd argued long and hard with the first Copy, but after that, he'd never had the stomach for it.

'Well, I've got news for you: You're not.'

With his eyes still closed, he gripped the release lever.

I'm nothing: a dream, a soon-to-be-forgotten dream.

His fingernails needed cutting; they dug painfully into the skin of his palm.

Had he never, in a dream, feared the extinction of waking? Maybe he had-but a dream was not a life. If the only way he could 'reclaim' his body, 'reclaim' his world, was to wake and forget-

He pulled the lever.

After a few seconds, he emitted a constricted sob-a sound more of confusion than any kind of emotion-and opened his eyes.

The lever had come away in his hand.

He stared dumbly at this metaphor for... what? A bug in the termination software? Some kind of hardware glitch?

Feeling-at last-truly dreamlike, he unstrapped the parachute, and unfastened the neatly packaged bundle.

Inside, there was no illusion of silk, or Kevlar, or whatever else there might plausibly have been. Just a sheet of paper. A note.

Dear Paul,

The night after the scan was completed, I looked back over the whole preparatory stage of the project, and did a great deal of soul-searching. And I came to the conclusion that-right up to the very last moment-my attitude had been poisoned with ambivalence.

With hindsight, I realized just how foolish my qualms were-but that was too late for you. I couldn't afford to ditch you, and have myself scanned yet again. So, what could I do?

This: I put your awakening on hold for a while, and tracked down someone who could make a few alterations to the virtual-environment utilities. I know that wasn't strictly legal... but you know how important it is to me that you-that we-succeed this time.

I trust you'll understand, and I'm confident that you'll accept the situation with dignity and equanimity.

Best wishes, Paul

He sank to his knees, still holding the note, staring at it with disbelief. I can't have done this. I can't have been so callous.

No?

He could never have done it to anyone else. He was sure of that. He wasn't a monster, a torturer, a sadist.

And he would never have gone ahead himself without the bale-out option as a last resort. Between his ludicrous fantasies of stoicism, and the sanity-preserving cop-out of relating only to the flesh-and-blood version, he must have had moments of clarity when the bottom line had been: If it's that bad, I can always put an end to it.

But as for making a Copy, and then-once its future was no longer his future, no longer anything for him to fear-taking away its power to escape... and rationalizing this hijacking as nothing more than an over-literal act of self-control...

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 modelled 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 surren-dered 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 rerun 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 potted 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 cafes; 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 of 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 burnt 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 slowdown, 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

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 wilfully, 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 livingroom 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 catalogues (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.

Maria invoked Camel's Eye and told it, 'Update my mask so it reacts as I did in that exchange.'

A brief silence followed. Maria imagined the synaptic weighting parameters being juggled in the mask's neural net, as the training algorithm hunted for values which would guarantee the required response. She thought: If I keep on doing this, the mask is going to end up as much like me as a fully fledged Copy. And what's the point of saving yourself from the tedium of talking to junk mail if... you're not? It was a deeply unpleasant notion... but masks were orders of magnitude less sophisticated than Copies; they had about as many neurons as the average goldfish-organized in a far less human fashion. Worrying about their 'experience' would be as ludicrous as feeling guilty about terminating junk mail.

Camel's Eye said, 'Done.'

It was only 8:15. The whole day loomed ahead, promising nothing but bills. With no contract work coming in for the past two months, Maria had written half a dozen pieces of consumer software-mostly home-security upgrades, supposedly in high demand. So far, she'd sold none of them; a few thousand people had read the catalogue entries, but nobody had been persuaded to download. The prospect of embarking on another such project wasn't exactly electrifying-but she had no real alternative. And once the recession was over and people started buying again, it would have been time well spent.

First, though, she needed to cheer herself up. If she worked in the Autoverse, just for half an hour or so-until nine o'clock at the latest-then she'd be able to face the rest of the day...

Then again, she could always try to face the rest of the day without bribing herself, just once. The Autoverse was a waste of money, and a waste of time-a hobby she could justify when things were going well, but an indulgence she could ill afford right now.

Maria put an end to her indecision in the usual way. She logged on to her Joint Supercomputer Network account-paying a fifty-dollar fee for the privilege, which she now had to make worthwhile. She slipped on her force gloves and prodded an icon, a wireframe of a cube, on the terminal's flatscreen-and the three-dimensional workspace in front of the screen came to life, borders outlined by a faint holographic grid. For a second, it felt like she'd plunged her hand into some kind of invisible vortex: magnetic fields gripped and twisted her glove, as start-up surges tugged at the coils in each joint at random-until the electronics settled into equilibrium, and a message flashed up in the middle of the workspace: you may now put on your gloves.

She jabbed another icon, a starburst labeled FIAT. The only visible effect was the appearance of a small menu strip hovering low in the foreground-but to the cluster of programs she'd invoked, the cube of thin air in front of her terminal now corresponded to a small, empty universe.

Maria summoned up a single molecule of nutrose, represented as a ball-and-stick model, and, with a flick of a gloved forefinger, imparted a slow spin. The vertices of the crimped hexagonal ring zig-zagged above and below the molecule's average plane; one vertex was a divalent blue atom, linked only to its neighbors in the ring; the other five were all tetravalent greens, with two bonds left over for other attachments. Each green was joined to a small, monovalent red-on the top side if the vertex was raised, on the bottom if it was lowered-and four of them also sprouted short horizontal spikes, built from a blue and a red, pointing away from the ring. The fifth green held out a small cluster of atoms instead: a green with two reds, and its own blue-red spike.

The viewing software rendered the molecule plausibly solid, taking into account the effects of ambient light; Maria watched it spin above the desktop, admiring the not-quite-symmetrical form. A real-world chemist, she mused, would take one look at this and say: Glucose. Green is carbon, blue is oxygen, red is hydrogen... no? No. They'd stare awhile; put on the gloves and give the impostor a thorough grope; whip a protractor out of the toolbox and measure a few angles; invoke tables of bond formation energies and vibrational modes; maybe even demand to see nuclear magnetic resonance spectra (not available-or, to put it less coyly, not applicable). Finally, with the realization of blasphemy dawning, they'd tear their hands from the infernal machinery, and bolt from the room screaming, 'There is no Periodic Table but Mendeleev's! There is no Periodic Table but Mendeleev's!'

The Autoverse was a 'toy' universe, a computer model which obeyed its own simplified 'laws of physics'-laws far easier to deal with mathematically than the equations of real-world quantum mechanics. Atoms could exist in this stylized universe, but they were subtly different from their real-world counterparts; the Autoverse was no more a faithful simulation of the real world than the game of chess was a faithful simulation of medieval warfare. It was far more insidious than chess, though, in the eyes of many real-world chemists. The false chemistry it supported was too rich, too complex, too seductive by far.

Maria reached into the workspace again, halted the molecule's spin, deftly plucked both the lone red and the blue-red spike from one of the greens, then reattached them, swapped, so that the spike now pointed upward. The gloves' force and tactile feedback, the molecule's laser-painted image, and the faint clicks that might have been plastic on plastic as she pushed the atoms into place, combined to create a convincing impression of manipulating a tangible object built out of solid spheres and rods.

This virtual ball-and-stick model was easy to work with-but its placid behavior in her hands had nothing to do with the physics of the Autoverse, temporarily held in abeyance. Only when she released her grip was the molecule allowed to express its true dynamics, oscillating wildly as the stresses induced by the alteration were redistributed from atom to atom, until a new equilibrium geometry was found.

Maria watched the delayed response with a familiar sense of frustration; she could never quite resign herself to accepting the handling rules, however convenient they were. She'd thought about trying to devise a more authentic mode of interaction, offering the chance to feel what it was 'really like' to grasp an Autoverse molecule, to break and re-form its bonds-instead of everything turning to simulated plastic at the touch of a glove. The catch was, if a molecule obeyed only Autoverse physics-the internal logic of the self-contained computer model-then how could she, outside the model, interact with it at all? By constructing little surrogate hands in the Autoverse, to act as remote manipulators? Construct them out of what? There were no molecules small enough to build anything finely structured, at that scale; the smallest rigid polymers which could act as 'fingers' would be half as thick as the entire nutrose ring. In any case, although the target molecule would be free to interact with these surrogate hands according to pure Autoverse physics, there'd be nothing authentic about the way the hands themselves magically followed the movements of her gloves. Maria could see no joy in simply shifting the point where the rules were broken-and the rules had to be broken, somewhere. Manipulating the contents of the Autoverse meant violating its laws. That was obvious... but it was still frustrating.

She saved the modified sugar, optimistically dubbing it mutose. Then, changing the length scale by a factor of a million, she started up twenty-one tiny cultures of Autobacterium lamberti, in solutions ranging from pure nutrose, to a fifty-fifty mixture, to one hundred percent mutose.

She gazed at the array of Petri dishes floating in the workspace, their contents portrayed in colors which coded for the health of the bacteria. 'False colors'... but that phrase was tautological. Any view of the Autoverse was necessarily stylized: a color-coded map, displaying selected attributes of the region in question. Some views were more abstract, more heavily processed than others-in the sense that a map of the Earth, color-coded to show the health of its people, would be arguably more abstract than one displaying altitude or rain-fall-but the real-world ideal of an unadulterated, naked-eye view was simply untranslatable.

A few of the cultures were already looking decidedly sick, fading from electric blue to dull brown. Maria summoned up a three-dimensional graph, showing population versus time for the full range of nutrient mixtures. The cultures with only a trace of the new stuff were, predictably, growing at almost the pace of the control; with increasing mutose substitution the ascent gradually slowed, until, around the eighty-five percent line, the population was static. Beyond that were ever steeper trajectories into extinction. In small doses, mutose was simply irrelevant, but at high enough concentrations it was insidious: similar enough to nutrose-A. lamberti's usual food-to be taken part-way through the metabolic process, competing for the same enzymes, tying up valuable biochemical resources... but eventually reaching a step where that one stray blue-red spike formed an insurmountable barrier to the reaction geometry, leaving the bacterium with nothing but a useless byproduct and a net energy loss. A culture with ninety percent mutose was a world where ninety per cent of the food supply had no nutritional value whatsoever-but had to be ingested indiscriminately along with the worthwhile ten percent. Consuming ten times as much for the same return wasn't a viable solution; to survive in the long term, A. lamberti would have to chance upon some means of rejecting mutose before wasting energy on it-or, better still, find a way to turn it back into nutrose, transforming it from a virtual poison into a source of food.

Maria displayed a histogram of mutations occurring in the bacteria's three nutrose epimerase genes; the enzymes these genes coded for were the closest things A. lamberti had to a tool to render mutose digestible-although none, in their original form, would do the job. No mutants had yet persisted for more than a couple of generations; all the changes so far had evidently done more harm than good. Partial sequences of the mutant genes scrolled by in a small window; Maria gazed at the blur of codons, and mentally urged the process on-if not straight toward the target (since she had no idea what that was), then at least... outward, blindly, into the space of all possible mistakes.

It was a nice thought. The only trouble was, certain portions of the genes were especially prone to particular copying errors, so most of the mutants were 'exploring' the same dead ends again and again.

Arranging for A. lamberti to mutate was easy; like a real-world bacterium, it made frequent errors every time it duplicated its analogue of DNA. Persuading it to mutate 'usefully' was something else. Max Lambert himself-inventor of the Autoverse, creator of A. lamberti, hero to a generation of cellular-automaton and artificial-life freaks-had spent much of the last fifteen years of his life trying to discover why the subtle differences between real-world and Autoverse biochemistry made natural selection so common in one system, and so elusive in the other. Exposed to the kind of stressful opportunities which E. coli would have exploited within a few dozen generations, strain after strain of A. lamberti had simply died out.

Only a few die-hard enthusiasts still continued Lambert's work. Maria knew of just seventy-two people who'd have the slightest idea what it meant if she ever succeeded. The artificial life scene, now, was dominated by the study of Copies-patchwork creatures, mosaics of ten thousand different ad hoc rules... the antithesis of everything the Autoverse stood for.

Real-world biochemistry was far too complex to simulate in every last detail for a creature the size of a gnat, let alone a human being. Computers could model all the processes of life-but not on every scale, from atom to organism, all at the same time. So the field had split three ways. In one camp, traditional molecular biochemists continued to extend their painstaking calculations, solving Schrödinger's equation more or less exactly for ever larger systems, working their way up to entire replicating strands of DNA, whole mitochondrial sub-assemblies, significant patches of the giant carbohydrate chain-link fence of a cell wall... but spending ever more on computing power for ever diminishing returns.

At the other end of the scale were Copies: elaborate refinements of whole-body medical simulations, originally designed to help train surgeons with virtual operations, and to take the place of animals in drug tests. A Copy was like a high-resolution CAT scan come to life, linked to a medical encyclopedia to spell out how its every tissue and organ should behave... walking around inside a state-of-the-art architectural simulation. A Copy possessed no individual atoms or molecules; every organ in its virtual body came in the guise of specialized sub-programs which knew (in encyclopedic, but not atomic, detail) how a real liver or brain or thyroid gland functioned... but which couldn't have solved Schrödinger's equation for so much as a single protein molecule. All physiology, no physics.

Lambert and his followers had staked out the middle ground. They'd invented a new physics, simple enough to allow several thousand bacteria to fit into a modest computer simulation, with a consistent, unbroken hierarchy of details existing right down to the subatomic scale. Everything was driven from the bottom up, by the lowest level of physical laws, just as it was in the real world.

The price of this simplicity was that an Autoverse bacterium didn't necessarily behave like its real-world counterparts. A. lamberti had a habit of confounding traditional expectations in bizarre and unpredictable ways-and for most serious microbiologists, that was enough to render it worthless.

For Autoverse junkies, though, that was the whole point.

Maria brushed aside the diagrams concealing her view of the Petri dishes, then zoomed in on one thriving culture, until a single bacterium filled the workspace. Color-coded by 'health,' it was a featureless blue blob; but even when she switched to a standard chemical map there was no real structure visible, apart from the cell wall-no nucleus, no organelles, no flagella; A. lamberti wasn't much more than a sac of protoplasm. She played with the representation, making the fine strands of the unraveled chromosomes appear; highlighting regions where protein synthesis was taking place; rendering visible the concentration gradients of nutrose and its immediate metabolites. Computationally expensive views; she cursed herself (as always) for wasting money, but failed (as always) to shut down everything but the essential analysis software (and the Autoverse itself), failed to sit gazing into thin air, waiting patiently for a result.

Instead, she zoomed in closer, switched to atomic colors (but left the pervasive aqua molecules invisible), temporarily halted time to freeze the blur of thermal motion, then zoomed in still further until the vague specks scattered throughout the workspace sharpened into the intricate tangles of long-chain lipids, polysaccharides, peptidoglycans. Names stolen unmodified from their real-world analogues-but screw it, who wanted to spend their life devising a whole new biochemical nomenclature? Maria was sufficiently impressed that Lambert had come up with distinguishable colors for all thirty-two Autoverse atoms, and unambiguous names to match.

She tracked through the sea of elaborate molecules-all of them synthesized by A. lamberti from nothing but nutrose, aqua, pneuma, and a few trace elements. Unable to spot any mutose molecules, she invoked Maxwell's Demon and asked it to find one. The perceptible delay before the program responded always drove home to her the sheer quantity of information she was playing with-and the way in which it was organized. A traditional biochemical simulation would have been keeping track of every molecule, and could have told her the exact location of the nearest altered sugar almost instantaneously. For a traditional simulation, this catalogue of molecules would have been the 'ultimate truth'-nothing would have 'existed,' except by virtue of an entry in the Big List. In contrast, the 'ultimate truth' of the Autoverse was a vast array of cubic cells of subatomic dimensions-and the primary software dealt only with these cells, oblivious to any larger structures. Atoms in the Autoverse were like hurricanes in an atmospheric model (only far more stable); they arose from the simple rules governing the smallest elements of the system. There was no need to explicitly calculate their behavior; the laws governing individual cells drove everything that happened at higher levels. Of course, a swarm of demons could have been used to compile and maintain a kind of census of atoms and molecules-at great computational expense, rather defeating the point. And the Autoverse itself would have churned on, regardless.

Maria locked her viewpoint to the mutose molecule, then restarted time, and everything but that one hexagonal ring smeared into translucence. The molecule itself was only slightly blurred; the current representational conventions made the average positions of the atoms clearly visible, with the deviations due to bond vibration merely suggested by faint ghostly streaks.

She zoomed in until the molecule filled the workspace. She didn't know what she was hoping to see: a successful mutant epimerase enzyme suddenly latch onto the ring and shift the aberrant blue-red spike back into the horizontal position? Questions of probability aside, it would have been over before she even knew it had begun. That part was easily fixed: she instructed Maxwell's Demon to keep a rolling buffer of a few million clock ticks of the molecule's history, and to replay it at a suitable rate if any structural change occurred.

Embedded in a 'living' organism, the mutose ring looked exactly the same as the prototype she'd handled minutes before: red, green and blue billiard balls, linked by thin white rods. It seemed like an insult for even a bacterium to be composed of such comic-book molecules. The viewing software was constantly inspecting this tiny region of the Autoverse, identifying the patterns that constituted atoms, checking for overlaps between them to decide which was bonded to which, and then displaying a nice, neat, stylized picture of its conclusions. Like the handling rules which took this representation at face value, it was a useful fiction, but...

Maria slowed down the Autoverse clock by a factor of ten billion, then popped up the viewing menu and hit the button marked RAW. The tidy assembly of spheres and rods melted into a jagged crown of writhing polychromatic liquid metal, waves of color boiling away from the vertices to collide, merge, flow back again, wisps licking out into space.

She slowed down time a further hundredfold, almost freezing the turmoil, and then zoomed in to the same degree. The individual cubic cells which made up the Autoverse were visible now, changing state about once a second. Each cell's 'state'-a whole number between zero and two hundred and fifty-five-was recomputed every clock cycle, according to a simple set of rules applied to its own previous state, and the states of its closest neighbors in the three-dimensional grid. The cellular automaton which was the Autoverse did nothing whatsoever but apply these rules uniformly to every cell; these were its fundamental 'laws of physics.' Here, there were no daunting quantum-mechanical equations to struggle with-just a handful of trivial arithmetic operations, performed on integers. And yet the impossibly crude laws of the Autoverse still managed to give rise to 'atoms' and 'molecules' with a 'chemistry' rich enough to sustain 'life.'

Maria followed the fate of a cluster of golden cells spreading through the lattice-the cells themselves didn't move, by definition, but the pattern advanced-infiltrating and conquering a region of metallic blue, only to be invaded and consumed in turn by a wave of magenta.

If the Autoverse had a 'true' appearance, this was it. The palette which assigned a color to each state was still 'false'-still completely arbitrary-but at least this view revealed the elaborate three-dimensional chess game which underpinned everything else.

Everything except the hardware, the computer itself.

Maria reverted to the standard clock rate, and a macroscopic view of her twenty-one Petri dishes-just as a message popped up in the foreground:

JSN regrets to advise you that your resources have been diverted to a higher bidder. A snapshot of your task has been preserved in mass storage, and will be available to you when you next log on. Thank you for using our services.

Maria sat and swore angrily for half a minute-then stopped abruptly, and buried her face in her hands. She shouldn't have been logged on in the first place. It was insane, squandering her savings playing around with mutant A. lamberti-but she kept on doing it. The Autoverse was so seductive, so hypnotic... so addictive.

Whoever had elbowed her off the network had done her a favor-and she'd even have her fifty-dollar log-on fee refunded, since she'd been thrown right out, not merely slowed down to a snail's pace.

Curious to discover the identity of her unintentional benefactor, she logged on directly to the QIPS Exchange-the marketplace where processing power was bought and sold. The connection to JSN had passed through the Exchange, transparently; her terminal was programmed to bid at the market rate automatically, up to a certain ceiling. Right now, though, some outfit calling itself Operation Butterfly was buying QIPS-quadrillions of instructions per second-at six hundred times that ceiling, and had managed to acquire one hundred percent of the planet's traded computing power.

Maria was stunned; she'd never seen anything like it. The pie chart of successful bidders-normally a flickering kaleidoscope of thousands of needle-thin slices-was a solid, static disk of blue. Aircraft would not be dropping out of the sky, world commerce would not have ground to a halt... but tens of thousands of academic and industrial researchers relied on the Exchange every day for tasks it wasn't worth owning the power to perform in-house. Not to mention a few thousand Copies. For one user to muscle in and outbid everyone else was unprecedented. Who needed that much computing power? Big business, big science, the military? All had their own private hardware-usually in excess of their requirements. If they traded at all, it was to sell their surplus capacity.

Operation Butterfly? The name sounded vaguely familiar. Maria logged on to a news system and searched for reports which mentioned the phrase. The most recent was three months ago:

Kuala Lumpar-Monday, August 8th, 2050: A meeting of environmental ministers from the Association of South-East Asian Nations (ASEAN) today agreed to proceed with the latest stage of Operation Butterfly, a controversial plan to attempt to limit the damage and loss of life caused by Greenhouse Typhoons in the region.

The long-term aim of the project is to utilize the so-called Butterfly Effect to divert typhoons away from vulnerable populated areas-or perhaps prevent them from forming in the first place.

Maria said, 'Define 'Butterfly Effect.'' A second window opened up in front of the news report:

Butterfly Effect: This term was coined by meteorologist Edward Lorenz in the late 1970s, to dramatize the futility of trying to make long-term weather forecasts. Lorenz pointed out that meteorological systems were so sensitive to their initial conditions that a butterfly flapping its wings in Brazil could be enough to determine whether or not there was a tornado in Texas a month later. No computer model could ever include such minute details-so any attempt to forecast the weather more than a few days in advance was doomed to failure.

However, in the 1990s the term began to lose its original, pessimistic connotations. A number of researchers discovered that, although the effects of small, random influences made a chaotic system unpredictable, under certain conditions the same sensitivity could be deliberately exploited to steer the system in a chosen direction. The same kind of processes which magnified the flapping of butterflies' wings into tornadoes could also magnify the effects of systematic intervention, allowing a degree of control out of all proportion to the energy expended.

The Butterfly Effect now commonly refers to the principle of controlling a chaotic system with minimum force, through a detailed knowledge of its dynamics. This technique has been applied in a number of fields, including chemical engineering, stock-market manipulation, fly-by-wire aeronautics, and the proposed ASEAN weather-control system, Operation Butterfly.

There was more, but Maria took the cue and switched back to the article.

Meteorologists envisage dotting the waters of the tropical western Pacific and the South China Sea with a grid of hundreds of thousands of 'weather-control' rigs-solar-powered devices designed to alter the local temperature on demand by pumping water between different depths. Theoretical models suggest that a sufficient number of rigs, under elaborate computer control, could be used to influence large-scale weather patterns, 'nudging' them toward the least harmful of a number of finely balanced possible outcomes.

Eight different rig prototypes have been tested in the open ocean, but before engineers select one design for mass production, an extensive feasibility study will be conducted. Over a three-year period, any potentially threatening typhoon will be analyzed by a computer model of the highest possible resolution, and the effects of various numbers and types of the as yet nonexistent rigs will be included in the model. If these simulations demonstrate that intervention could have yielded significant savings in life and property, ASEAN's ministerial council will have to decide whether or not to spend the estimated sixty billion dollars required to make the system a reality. Other nations are observing the experiment with interest.

Maria leaned back from the screen, impressed. A computer model of the highest possible resolution. And they'd meant it, literally. They'd bought up all the number-crunching power on offer-paying a small fortune, but only a fraction of what it would have cost to buy the same hardware outright.

Nudging typhoons! Not yet, not in reality... but who could begrudge Operation Butterfly their brief monopoly, for such a grand experiment? Maria felt a vicarious thrill at the sheer scale of the endeavor-and then a mixture of guilt and resentment at being a mere bystander. She had no qualifications in atmospheric or oceanic physics, no PhD in chaos theory-but in a project of that size, there must have been a few hundred jobs offered to mere programmers. When the tenders had gone out over the network, she'd probably been busy on some shitty contract to improve the tactile qualities of beach sand for visitors to the Virtual Gold Coast-either that, or tinkering with the genome of A. lamberti, trying to become the first person in the world to bludgeon a simulated bacterium into exhibiting natural selection.

It wasn't clear how long Operation Butterfly would spend monitoring each typhoon-but she could forget about returning to the Autoverse for the day.

Reluctantly, she logged off the news system-fighting the temptation to sit and wait for the first reports of the typhoon in question, or the response of other supercomputer users to the great processing buy-out-and began reviewing her plans for a new intruder surveillance package.

2

(Remit not paucity)

NOVEMBER 2050

'What I'm asking for is two million ecus. What I'm offering you is immortality.'

Thomas Riemann's office was compact but uncluttered, smartly furnished without being ostentatious. The single large window offered a sweeping view of Frankfurt-looking north across the river, as if from Sachsenhausen, toward the three jet-black towers of the Siemens/Deutsche Bank Center-which Thomas believed was as honest as any conceivable alternative. Half the offices in Frankfurt itself looked out over recorded tropical rainforests, stunning desert gorges, Antarctic ice shelves-or wholly synthetic landscapes: rural-idyllic, futuristic, interplanetary, or simply surreal. With the freedom to choose whatever he liked, he'd selected this familiar sight from his corporeal days; sentimental, perhaps, but at least it wasn't ludicrously inappropriate.

Thomas turned away from the window, and regarded his visitor with good-natured skepticism. He replied in English; the office software could have translated for him-and would have chosen the very same words and syntax, having been cloned from his own language centers-but Thomas still preferred to use the version 'residing inside' his own 'skull.'

'Two million? What's the scheme? Let me guess. Under your skillful management, my capital will grow at the highest possible rate consistent with the need for total security. The price of computation is sure to fall again, sooner or later; the fact that it's risen for the last fifteen years only makes that more likely than ever. So: it may take a decade or two-or three, or four-but eventually, the income from my modest investment will be enough to keep me running on the latest hardware, indefinitely... while also providing you with a small commission, of course.' Thomas laughed, without malice. 'You don't seem to have researched your prospective client very thoroughly. You people usually have immaculate intelligence-but I'm afraid you've really missed the target with me. I'm in no danger of being shut down. The hardware we're using, right now, isn't leased from anyone; it's wholly owned by a foundation I set up before my death. My estate is being managed to my complete satisfaction. I have no problems-financial, legal, peace of mind-for you to solve. And the last thing in the world I need is a cheap and nasty perpetuity fund. Your offer is useless to me.'

Paul Durham chose to display no sign of disappointment. He said, 'I'm not talking about a perpetuity fund. I'm not selling any kind of financial service. Will you give me a chance to explain?'

Thomas nodded affably. 'Go ahead. I'm listening.' Durham had flatly refused to state his business in advance, but Thomas had decided to see him anyway-anticipating a perverse satisfaction in confirming that the man's mysterious coyness hid nothing out of the ordinary. Thomas almost always agreed to meet visitors from outside-even though experience had shown that most were simply begging for money, one way or another. He believed that anyone willing to slow down their brain by a factor of seventeen, solely for the privilege of talking to him face to face, deserved a hearing-and he wasn't immune to the intrinsic flattery of the process, the unequal sacrifice of time.

There was more to it, though, than flattery.

When other Copies called on him in his office, or sat beside him at a boardroom table, everyone was 'present' in exactly the same sense. However bizarre the algorithmic underpinnings of the encounter, it was a meeting of equals. No boundaries were crossed.

A visitor, though, who could lift and empty a coffee cup, who could sign a document and shake your hand-but who was, indisputably, lying motionless on a couch in another (higher?) metaphysical plane-came charged with too many implicit reminders of the nature of things to be faced with the same equanimity. Thomas valued that. He didn't want to grow complacent-or worse. Visitors helped him to retain a clear sense of what he'd become.

Durham said, 'Of course I'm aware of your situation-you have one of the most secure arrangements I've seen. I've read the incorporation documents of the Soliton Foundation, and they're close to watertight. Under present legislation.'

Thomas laughed heartily. 'But you think you can do better? Soliton pays its most senior lawyers almost a million a year; you should have got yourself some forged qualifications and asked me to employ you. Under present legislation! When the laws change, believe me, they'll change for the better. I expect you know that Soliton spends a small fortune lobbying for improvement-and it's not alone. The trend is in one direction: there are more Copies every year, and most of them have de facto control over virtually all of the wealth they owned when they were alive. I'm afraid your timing's atrocious if you're planning on using scare tactics; I received a report last week predicting full human rights-in Europe, at least-by the early sixties. Ten years isn't long for me to wait. I've grown used to the current slowdown factor; even if processor speeds improve, I could easily choose to keep living at the rate I'm living now, for another six or seven subjective months, rather than pushing all the things I'm looking forward to-like European citizenship-further into the future.'

Durham's puppet inclined its head in a gesture of polite assent; Thomas had a sudden vision of a second puppet-one Durham truly felt himself to be inhabiting-hunched over a control panel, hitting a button on an etiquette sub-menu. Was that paranoid? But any sensible mendicant visitor would do just that, conducting the meeting at a distance rather than exposing their true body language to scrutiny.

The visible puppet said, 'Why spend a fortune upgrading, for the sake of effectively slowing down progress? And I agree with you about the outlook for reform-in the short term. Of course people begrudge Copies their longevity, but the PR has been handled remarkably well. A few carefully chosen terminally ill children are scanned and resurrected every year: better than a trip to Disney World. There's discreet sponsorship of a sitcom about working-class Copies, which makes the whole idea less threatening. The legal status of Copies is being framed as a human rights issue, especially in Europe: Copies are disabled people, no more, no less-really just a kind of radical amputee-and anyone who talks about decadent rich immortals getting their hands on all the wealth is shouted down as a neo-Nazi.

'So you might well achieve citizenship in a decade. And if you're lucky, the situation could be stable for another twenty or thirty years after that. But... what's twenty or thirty years to you? Do you honestly think that the status quo will be tolerated for ever?''

Thomas said, 'Of course not-but I'll tell you what would be 'tolerated': scanning facilities, and computing power, so cheap that everyone on the planet could be resurrected. Everyone who wanted it. And when I say cheap, I mean at a cost comparable to a dose of vaccine at the turn of the century. Imagine that. Death could be eradicated-like smallpox or malaria. And I'm not talking about some solipsistic nightmare; by then, telepresence robots will let Copies interact with the physical world as fully as if they were human. Civilization wouldn't have deserted reality-just transcended biology.'

'That's a long, long way in the future.'

'Certainly. But don't accuse me of thinking in the short term.'

'And in the meantime? The privileged class of Copies will grow larger, more powerful-and more threatening to the vast majority of people, who still won't be able to join them. The costs will come down, but not drastically-just enough to meet some of the explosion in demand from the executive class, once they throw off their qualms, en masse. Even in secular Europe, there's a deeply ingrained prejudice that says dying is the responsible, the moral thing to do. There's a Death Ethic-and the first substantial segment of the population abandoning it will trigger a huge backlash. A small enough elite of giga-rich Copies is accepted as a freak show; tycoons can get away with anything, they're not expected to act like ordinary people. But just wait until the numbers go up by a factor of ten.'

Thomas had heard it all before. 'We may be unpopular for a while. I can live with that. But you know, even now we're vilified far less than people who strive for organic hyper-longevity-transplants, cellular rejuvenation, whatever-because at least we're no longer pushing up the cost of health care, competing for the use of overburdened medical facilities. Nor are we consuming natural resources at anything like the rate we did when we were alive. If the technology improves sufficiently, the environmental impact of the wealthiest Copy could end up being less than that of the most ascetic living human. Who'll have the high moral ground then? We'll be the most ecologically sound people on the planet.'

Durham smiled. The puppet. 'Sure-and it could lead to some nice ironies if it ever came true. But even low environmental impact might not seem so saintly, when the same computing power could be used to save tens of thousands of lives through weather control.'

'Operation Butterfly has inconvenienced some of my fellow Copies very slightly. And myself not at all.'

'Operation Butterfly is only the beginning. Crisis management, for a tiny part of the planet. Imagine how much computing power it would take to render sub-Saharan Africa free from drought.'

'Why should I imagine that, when the most modest schemes are still unproven? And even if weather control turns out to be viable, more supercomputers can always be built. It doesn't have to be a matter of Copies versus flood victims.'

'There's a limited supply of computing power right now, isn't there? Of course it will grow-but the demand, from Copies, and for weather control, is almost certain to grow faster. Long before we get to your deathless Utopia, we'll hit a bottle-neck-and I believe that will bring on a time when Copies are declared illegal. Worldwide. If they've been granted human rights, those rights will be taken away. Trusts and foundations will have their assets confiscated. Supercomputers will be heavily policed. Scanners-and scan files-will be destroyed. It may be forty years before any of this happens-or it may be sooner. Either way, you need to be prepared.'

Thomas said mildly, 'If you're fishing for a job as a futurology consultant, I'm afraid I already employ several-highly qualified-people who do nothing but investigate these trends. Right now, everything they tell me gives me reason to be optimistic-and even if they're wrong, Soliton is ready for a very wide range of contingencies.'

'If your whole foundation is eviscerated, do you honestly believe it will be able to ensure that a snapshot of you is hidden away safely-and then resurrected after a hundred years or more of social upheaval? A vault full of ROM chips at the bottom of a mine shaft could end up taking a one-way trip into geological time.'

Thomas laughed. 'And a meteor could hit the planet tomorrow, wiping out this computer, all of my backups, your organic body... anything and everything. Yes, there could be a revolution which pulls the plug on my world. It's unlikely, but it's not impossible. Or there could be a plague, or an ecological disaster, which kills billions of organic humans but leaves all the Copies untouched. There are no certainties for anyone.'

'But Copies have so much more to lose.'

Thomas was emphatic; this was part of his personal litany. 'I've never mistaken what I have-a very good chance of a prolonged existence-for a guarantee of immortality.'

Durham said flatly, 'Quite right. You have no such thing. Which is why I'm here offering it to you.'

Thomas regarded him uneasily. Although he'd had all the ravages of surgery edited out of his final scan file, he'd kept a scar on his right forearm, a small memento of a youthful misadventure. He stroked it, not quite absentmindedly; conscious of the habit, conscious of the memories that the scar encoded-but practiced at refusing to allow those memories to hold his gaze.

Finally, he said, 'Offering it how? What can you possibly do-for two million ecus-that Soliton can't do a thousand times better?'

'I can run a second version of you, entirely out of harm's way. I can give you a kind of insurance-against an anti-Copy backlash... or a meteor strike... or whatever else might go wrong.'

Thomas was momentarily speechless. The subject wasn't entirely taboo, but he couldn't recall anyone raising it quite so bluntly before. He recovered swiftly. 'I have no wish to run a second version, thank you. And... what do you mean, 'out of harm's way'? Where's your invulnerable computer going to be? In orbit? Up where it would only take a pebble-sized meteor to destroy it, instead of a boulder?'

'No, not in orbit. And if you don't want a second version, that's fine. You could simply move.'

'Move where? Underground? To the bottom of the ocean? You don't even know where this office is being implemented, do you? What makes you think you can offer a superior site-for such a ridiculous price-when you don't have the faintest idea how secure I am already?' Thomas was growing disappointed, and uncharacteristically irritable. 'Stop making these inflated claims, and get to the point. What are you selling?'

Durham shook his head apologetically. 'I can't tell you that. Not yet. If I tried to explain it, out of the blue, it would make no sense. You have to do something first. Something very simple.'

'Yes? And what's that?'

'You have to conduct a small experiment.'

Thomas scowled. 'What kind of experiment? Why?'

And Durham-the software puppet, the lifeless shell animated by a being from another plane-looked him in the eye and said, 'You have to let me show you exactly what you are.'

3

(Rip, tie, cut toy man)

JUNE 2045

Paul-or the flesh-and-blood man whose memories he'd inherited-had traced the history of Copies back to the turn of the century, when researchers had begun to fine-tune the generic computer models used for surgical training and pharmacology, transforming them into customized versions able to predict the needs and problems of individual patients. Drug therapies were tried out in advance on models which incorporated specific genetic and biochemical traits, allowing doses to be optimized and any idiosyncratic side-effects anticipated and avoided. Elaborate operations were rehearsed and perfected in Virtual Reality, on software bodies with anatomical details-down to the finest capillaries-based on the flesh-and-blood patient's tomographic scans.

These early models included a crude approximation of the brain, perfectly adequate for heart surgery or immunotherapy-and even useful to a degree when dealing with gross cerebral injuries and tumours-but worthless for exploring more subtle neurological problems.

Imaging technology steadily improved, though-and by 2020, it had reached the point where individual neurons could be mapped, and the properties of individual synapses measured, non-invasively. With a combination of scanners, every psychologically relevant detail of the brain could be read from the living organ-and duplicated on a sufficiently powerful computer.

At first, only isolated neural pathways were modeled: portions of the visual cortex of interest to designers of machine vision, or sections of the limbic system whose role had been in dispute. These fragmentary neural models yielded valuable results, but a functionally complete representation of the whole organ-embedded in a whole body-would have allowed the most delicate feats of neurosurgery and psychopharmacology to be tested in advance. For several years, though, no such model was built-in part, because of a scarcely articulated unease at the prospect of what it would mean. There were no formal barriers standing in the way-government regulatory bodies and institutional ethics committees were concerned only with human and animal welfare, and no laboratory had yet been fire-bombed by activists for its inhumane treatment of physiological software-but still, someone had to be the first to break all the unspoken taboos.

Someone had to make a high-resolution, whole-brain Copy-and let it wake, and talk.

In 2024, John Vines, a Boston neurosurgeon, ran a fully conscious Copy of himself in a crude Virtual Reality. Taking slightly less than three hours of real time (pulse racing, hyper-ventilating, stress hormones elevated), the first Copy's first words were: 'This is like being buried alive. I've changed my mind. Get me out of here.'

His original obligingly shut him down-but then later repeated the demonstration several times, without variation, reasoning that it was impossible to cause additional distress by running exactly the same simulation more than once.

When Vines went public, the prospects for advancing neurological research didn't rate a mention; within twenty-four hours-despite the Copy's discouraging testimony-the headlines were all immortality, mass migration into Virtual Reality, and the imminent desertion of the physical world.

Paul was twenty-four years old at the time, with no idea what to make of his life. His father had died the year before-leaving him a modest business empire, centered on a thriving retail chain, which he had no interest in managing. He'd spent seven years traveling and studying-science, history and philosophy-doing well enough at everything he tried, but unable to discover anything that kindled real intellectual passion. With no struggle for financial security ahead, he'd been sinking quietly into a state of bemused complacency.

The news of John Vines's Copy blasted away his indifference. It was as if every dubious promise technology had ever made to transform human life was about to be fulfilled, with a vengeance. Longevity would only be the start of it; Copies could evolve in ways almost impossible for organic beings: modifying their minds, redefining their goals, endlessly transmuting themselves. The possibilities were intoxicating-even as the costs and drawbacks of the earliest versions sank in, even as the inevitable backlash began, Paul was a child of the millennium; he was ready to embrace it all.

But the more time he spent contemplating what Vines had done, the more bizarre the implications seemed to be.

The public debate the experiment had triggered was heated, but depressingly superficial. Decades-old arguments raged again over just how much computer programs could ever have in common with human beings (psychologically, morally, metaphysically, information-theoretically... ) and even whether or not Copies could be 'truly' intelligent, 'truly' conscious. As more workers repeated Vines's result, their Copies soon passed the Turing test: no panel of experts quizzing a group of Copies and humans-by delayed video, to mask the time-rate difference-could tell which were which. But some philosophers and psychologists continued to insist that this demonstrated nothing more than 'simulated consciousness,' and that Copies were merely programs capable of faking a detailed inner life which didn't actually exist at all.

Supporters of the Strong AI Hypothesis insisted that consciousness was a property of certain algorithms-a result of information being processed in certain ways, regardless of what machine, or organ, was used to perform the task. A computer model which manipulated data about itself and its 'surroundings' in essentially the same way as an organic brain would have to possess essentially the same mental states. 'Simulated consciousness' was as oxymoronic as 'simulated addition.'

Opponents replied that when you modeled a hurricane, nobody got wet. When you modeled a fusion power plant, no energy was produced. When you modeled digestion and metabolism, no nutrients were consumed-no real digestion took place. So, when you modeled the human brain, why should you expect real thought to occur? A computer running a Copy might be able to generate plausible descriptions of human behavior in hypothetical scenarios-and even appear to carry on a conversation, by correctly predicting what a human would have done in the same situation-but that hardly made the machine itself conscious.

Paul had rapidly decided that this whole debate was a distraction. For any human, absolute proof of a Copy's sentience was impossible. For any Copy, the truth was self-evident: cogito ergo sum. End of discussion.

But for any human willing to grant Copies the same reasonable presumption of consciousness that they granted their fellow humans-and any Copy willing to reciprocate-the real point was this:

There were questions about the nature of this shared condition which the existence of Copies illuminated more starkly than anything which had come before them. Questions which needed to be explored, before the human race could confidently begin to bequeath its culture, its memories, its purpose and identity, to its successors.

Questions which only a Copy could answer. + + +

Paul sat in his study, in his favorite armchair (unconvinced that the texture of the surface had been accurately reproduced), taking what comfort he could from the undeniable absurdity of being afraid to experiment on himself further. He'd already 'survived' the 'transition' from flesh-and-blood human to computerized physiological model-the most radical stage of the project, by far. In comparison, tinkering with a few of the model's parameters should have seemed trivial.

Durham appeared on the terminal-which was otherwise still dysfunctional. Paul was already beginning to think of him as a bossy little djinn trapped inside the screen-rather than a vast, omnipotent deity striding the halls of Reality, pulling all the strings. The pitch of his voice was enough to deflate any aura of power and grandeur.

Squeak. 'Experiment one, trial zero. Baseline data. Time resolution one millisecond-system standard. Just count to ten, at one-second intervals, as near as you can judge it. Okay?'

'I think I can manage that.' He'd planned all this himself, he didn't need step-by-step instructions. Durham's image vanished; during the experiments, there could be no cues from real time.

Paul counted to ten. The djinn returned. Staring at the face on the screen, Paul realized that he had no inclination to think of it as 'his own.' Perhaps that was a legacy of distancing himself from the earlier Copies. Or perhaps his mental image of himself had never been much like his true appearance-and now, in defense of sanity, was moving even further away.

Squeak. 'Okay. Experiment one, trial number one. Time resolution five milliseconds. Are you ready?'

'Yes.'

The djinn vanished. Paul counted: 'One. Two. Three. Four. Five. Six. Seven. Eight. Nine. Ten.'

Squeak. 'Anything to report?'

'No. I mean, I can't help feeling slightly apprehensive, just knowing that you're screwing around with my... infrastructure. But apart from that, nothing.'

Durham's eyes no longer glazed over while he was waiting for the speeded-up reply; either he'd gained a degree of self-discipline, or-more likely-he'd interposed some smart editing software to conceal his boredom.

Squeak. 'Don't worry about apprehension. We're running a control, remember?'

Paul would have preferred not to have been reminded. He'd known that Durham must have cloned him, and would be feeding exactly the same sensorium to both Copies-while only making changes in the model's time resolution for one of them. It was an essential part of the experiment-but he didn't want to dwell on it. A third self, shadowing his thoughts, was too much to acknowledge on top of everything else.

Squeak. 'Trial number two. Time resolution ten milliseconds.'

Paul counted. The easiest thing in the world, he thought, when you're made of flesh, when you're made of matter, when the quarks and the electrons just do what comes naturally. Human beings were embodied, ultimately, in fields of fundamental particles-incapable, surely, of being anything other than themselves. Copies were embodied in computer memories as vast sets of numbers. Numbers which certainly could be interpreted as describing a human body sitting in a room... but it was hard to see that meaning as intrinsic, as necessary, when tens of thousands of arbitrary choices had been made about the way in which the model had been coded. Is this my blood sugar here... or my testosterone level? Is this the firing rate of a motor neuron as I raise my right hand... or a signal coming in from my retina as I watch myself doing it? Anybody given access to the raw data, but unaware of the conventions, could spend a lifetime sifting through the numbers without deciphering what any of it meant.

And yet no Copy buried in the data itself-ignorant of the details or not-could have the slightest trouble making sense of it all in an instant.

Squeak. 'Trial number three. Time resolution twenty milliseconds.'

'One. Two. Three.'

For time to pass for a Copy, the numbers which defined it had to change from moment to moment. Recomputed over and over again, a Copy was a sequence of snapshots, frames of a movie-or frames of computer animation.

But... when, exactly, did these snapshots give rise to conscious thought? While they were being computed? Or in the brief interludes when they sat in the computer's memory, unchanging, doing nothing but representing one static instant of the Copy's life? When both stages were taking place a thousand times per subjective second, it hardly seemed to matter, but very soon-

Squeak. 'Trial number four. Time resolution fifty milliseconds.'

What am I? The data? The process that generates it? The relationships between the numbers?

All of the above?

'One hundred milliseconds.'

'One. Two. Three.'

Paul listened to his voice as he counted-as if half expecting to begin to notice the encroachment of silence, to start perceiving the gaps in himself.

'Two hundred milliseconds.'

A fifth of a second. 'One. Two.' Was he strobing in and out of existence now, at five subjective hertz? The crudest of celluloid movies had never flickered at this rate. 'Three. Four.' He waved his hand in front of his face; the motion looked perfectly smooth, perfectly normal. And of course it did; he wasn't watching from the outside. 'Five. Six. Seven.' A sudden, intense wave of nausea passed through him but he fought it down, and continued. 'Eight. Nine. Ten.'

The djinn reappeared and emitted a brief, solicitous squeak. 'What's wrong? Do you want to stop for a while?'

'No, I'm fine.' Paul glanced around the innocent, sun-dappled room, and laughed. How would Durham handle it if the control and the subject had just given two different replies? He tried to recall his plans for such a contingency, but couldn't remember them-and didn't much care. It wasn't his problem any more.

Squeak. 'Trial number seven. Time resolution five hundred milliseconds.'

Paul counted-and the truth was, he felt no different. A little uneasy, yes-but factoring out any squeamishness, everything about his experience seemed to remain the same. And that made sense, at least in the long run-because nothing was being omitted, in the long run. His model-of-a-brain was only being fully described at half-second (model time) intervals-but each description still included the results of everything that 'would have happened' in between. Every half-second, his brain was ending up in exactly the state it would have been in if nothing had been left out.

'One thousand milliseconds.'

But... what was going on, in between? The equations controlling the model were far too complex to solve in a single step. In the process of calculating the solutions, vast arrays of partial results were being generated and discarded along the way. In a sense, these partial results implied-even if they didn't directly represent-events taking place within the gaps between successive complete descriptions. And when the whole model was arbitrary, who was to say that these implied events, buried a little more deeply in the torrent of data, were any 'less real' than those which were directly described?

'Two thousand milliseconds.'

'One. Two. Three. Four.'

If he seemed to speak (and hear himself speak) every number, it was because the effects of having said 'three' (and having heard himself say it) were implicit in the details of calculating how his brain evolved from the time when he'd just said 'two' to the time when he'd just said 'four.'

'Five thousand milliseconds.'

'One. Two. Three. Four. Five.'

Besides, hearing words that he'd never 'really' spoken wasn't much stranger than a Copy hearing anything at all. Even the standard millisecond clock rate of this world was far too coarse to resolve the full range of audible tones. Sound wasn't represented in the model by fluctuations in air pressure values-which couldn't change fast enough-but in terms of audio power spectra: profiles of intensity versus frequency. Twenty kilohertz was just a number here, a label; nothing could actually oscillate at that rate. Real ears analyzed pressure waves into components of various pitch; Paul knew that his brain was being fed the preexisting power spectrum values directly, plucked out of the nonexistent air by a crude patch in the model.

'Ten thousand milliseconds.'

'One. Two. Three.'

Ten seconds free-falling from frame to frame.

Fighting down vertigo, still counting steadily, Paul prodded the shallow cut he'd made in his forearm with the kitchen knife. It stung, convincingly. So where was this experience coming from? Once the ten seconds were up, his fully described brain would remember all of this... but that didn't account for what was happening now. Pain was more than the memory of pain. He struggled to imagine the tangle of billions of intermediate calculations, somehow 'making sense' of themselves, bridging the gap.

And he wondered: What would happen if someone shut down the computer, just pulled the plug-right now?

He didn't know what that meant, though. In any terms but his own, he didn't know when 'right now' was.

'Eight. Nine. Ten.'

Squeak. 'Paul-I'm seeing a slight blood pressure drop. Are you okay? How are you feeling?'

Giddy-but he said, 'The same as always.' And if that wasn't quite true, no doubt the control had told the same lie. Assuming...

'Tell me-which was I? Control, or subject?'

Squeak. Durham replied, 'I can't answer that-I'm still speaking to both of you. I'll tell you one thing, though: the two of you are still identical. There were some very small, transitory discrepancies, but they've died away completely now-and whenever the two of you were in comparable representations, all firing patterns of more than a couple of neurons were the same.'

Paul grunted dismissively; he had no intention of letting Durham know how unsettling the experiment had been. 'What did you expect? Solve the same set of equations two different ways, and of course you get the same results-give or take some minor differences in round-off errors along the way. You must. It's a mathematical certainty.'

Squeak. 'Oh, I agree.' The djinn wrote with one finger on the screen:

(1 + 2) + 3 = 1 + (2 + 3)

Paul said, 'So why bother with this stage at all? I know-I wanted to be rigorous, I wanted to establish solid foundations. But the truth is, it's a waste of our resources. Why not skip the bleeding obvious, and get on with the kind of experiment where the answer isn't a foregone conclusion?'

Squeak. Durham frowned reprovingly. 'I didn't realize you'd grown so cynical so quickly. AI isn't a branch of pure mathematics; it's an empirical science. Assumptions have to be tested. Confirming the so-called 'obvious' isn't such a dishonourable thing, is it? And if it's all so straightforward, why should you be afraid?'

'I'm not afraid: I just want to get it over with. But... go ahead. Prove whatever you think you have to prove, and then we can move on.'

Squeak. 'That's the plan. But I think we could both use a break now. I'll enable your communications-for incoming data only.' He turned away, reached off-screen, and hit a few keys on a second terminal.

Then he turned back to the camera, smiling-and Paul knew exactly what he was going to say.

Squeak. 'By the way, I just deleted one of you. I couldn't afford to keep you both running, when all you're going to do is laze around.'

Paul smiled back at him, although something inside him was screaming. 'Which one did you terminate?'

Squeak. 'What difference does it make? I told you, they were identical. And you're still here, aren't you? Whoever you are. Whichever you were.' + + +

Three weeks had passed outside since the day of the scan, but it didn't take Paul long to catch up with the state of the world; most of the fine details had been rendered irrelevant by subsequent events, and much of the ebb and flow had simply canceled itself out. Israel and Palestine had come close to war again, over alleged water treaty violations on both sides-but a joint peace rally had brought more than a million people onto the glassy plain that used to be Jerusalem, and the two governments had been forced to back down. Former US President Martin Sandover was still fighting extradition to Palau, to face charges arising from his role in the bloody coup d'etat of thirty-five; the Supreme Court had finally reversed a long-standing ruling which had granted him immunity from all foreign laws, and for a day or two things had looked promising-but then his legal team had discovered a whole new set of delaying tactics. In Canberra, another leadership challenge had come and gone, with the Prime Minister remaining undeposed. In a week-old report, one journalist described this, straight-faced, as 'high drama.' Paul thought: I guess you had to be there. Inflation had fallen by half a per-centage point; unemployment had risen by the same amount.

Paul scanned the old news reports rapidly, skimming over articles and fast-forwarding scenes which he felt sure he would have studied scrupulously, had they been fresh. He felt a curious sense of resentment, at having 'missed' so much-it was all there in front of him, now, but that wasn't the same at all.

And yet, he wondered, shouldn't he be relieved that he hadn't wasted his time on so much ephemeral detail? The very fact that he was now less than enthralled only proved how little of it had really mattered, in the long run.

Then again, what did? People didn't inhabit geological time. People inhabited hours and days; they had to care about things on that time scale.

People.

Paul plugged into real-time TV, and watched an episode of The Unclear Family flash by in less than two minutes, the soundtrack an incomprehensible squeal. A game show. A war movie. The evening news. It was as if he was in deep space, rushing back toward the Earth through a sea of Doppler-shifted broadcasts. The image was strangely comforting; his situation wasn't so bizarre, after all, if flesh-and-blood humans could find themselves in much the same relationship with the world as he did. Nobody would claim that the Doppler shift could rob someone of their humanity.

Dusk fell over the recorded city. He ate a microwaved soya protein stew-wondering if there was any good reason, moral or otherwise, to continue to be a vegetarian.

He listened to music until long after midnight. Tsang Chao, Michael Nyman, Philip Glass. It made no difference that each note 'really' lasted seventeen times as long as it should have, or that the audio ROM sitting in the player 'really' possessed no microstructure, or that the 'sound' itself was being fed into his model-of-a-brain by a computerized sleight-of-hand that bore no resemblance to the ordinary process of hearing. The climax of Glass's Mishima still seized him like a grappling hook through the heart.

And if the computations behind all this had been performed over millennia, by people flicking abacus beads, would he have felt exactly the same?

It was outrageous to admit it-but the answer had to be yes.

He lay in bed, wondering: Do I still want to wake from this dream?

The question remained academic, though; he still had no choice.

4

(Remit not paucity)

NOVEMBER 2050

Maria had arranged to meet Aden at the Nadir, an Oxford Street nightclub where he sometimes played and often went to write. He could usually get them both in for free, and the door-an intimidating, airlock-like contraption of ribbed black anodized steel-let her pass unchallenged after a brief security scan. Maria had once had a nightmare in which she'd been trapped in that chamber, a knife inexplicably strapped to her right boot-and, worse, her credit rating canceled. The thing had digested her like an insect in a Venus flytrap, while Aden stood on stage, singing one of his cut-up love songs.

Inside, the place was crowded for a Thursday night, and poorly lit as always; she finally spotted Aden sitting at a table near a side wall, listening to one of the bands and jotting down music, his face catching the glow of his notepad. So far as Maria could tell, he never seemed to be unduly influenced by anything he listened to while composing, but he claimed to be unable to work in silence, and preferred live performances for inspiration-or catalysis, or whatever it was.

She touched him on the shoulder. He looked up, took off his headset, and stood to kiss her. He tasted of orange juice.

He gestured with the headset. 'You should listen. Crooked Buddhist Lawyers on Crack. They're quite good.'

Maria glanced at the stage, although there was no way of telling who he meant. A dozen performers-four bands in all-stood enclosed in individual soundproof plastic cylinders. Most of the patrons were tuned in, wearing headsets to pick up one band's sound, and liquid crystal shades, flickering in synch with one group of cylinders, to render the other bands invisible. A few people were chatting quietly-and of the room's five possible soundtracks, Maria decided that this tranquil near-silence best suited her mood. Besides, she never much liked using nerve current inducers; although physically unable to damage the eardrums (sparing the management any risk of litigation), they always seemed to leave her ears-or her auditory pathways-ringing, regardless of the volume setting she chose.

'Maybe later.'

She sat beside Aden, and felt him tense slightly when their shoulders brushed, then force himself to relax. Or maybe not. Often when she thought she was reading his body language, she was making signals out of noise. She said, 'I got some junk mail today that looked just like you.'

'How flattering. I think. What was it selling?'

'The Church of the God Who Makes No Difference.'

He laughed. 'Every time I hear that, I think: they've got to change the name. A God which makes no difference doesn't rate the definite article or the pronoun 'who.''

'I'll rerun the program, and the two of you can fight it out.'

'No thanks.' He took a sip of his drink. 'Any non-junk mail? Any contracts?'

'No.'

'So... another day of terminal boredom?'

'Mostly.' Maria hesitated. Aden usually only pressed her for news when he had something to announce himself-and she was curious to find out what it was. But he volunteered nothing, so she went on to describe her encounter with Operation Butterfly.

Aden said, 'I remember hearing something about that. But I thought it was decades away.'

'The real thing probably is, but the simulations have definitely started. In a big way.'

He looked pained. 'Weather control? Who do they think they're kidding?'

Maria suppressed her irritation. 'The theory must look promising, or they wouldn't have taken it this far. Nobody spends a few million dollars an hour on supercomputer time without a good chance of a payoff.'

Aden snickered. 'Oh yes they do. And it's usually called Operation something-or-other. Remember Operation Radiant Way?'

'Yes, I remember.'

'They were going to seed the upper atmosphere with nanomachines which could monitor the temperature-and supposedly do something about it.'

'Manufacture particles which reflected certain wavelengths of solar radiation-and then disassemble them, as required.'

'In other words, cover the planet with a giant thermostatic blanket.'

'What's so terrible about that?'

'You mean, apart from the sheer technocratic hubris? And apart from the fact that releasing any kind of replicator into the environment is-still, thankfully-illegal? It wouldn't have worked. There were complications nobody had predicted-unstable mixing of air layers, wasn't it?-which would have counteracted most of the effect.'

Maria said, 'Exactly. But how would anyone have known that, if they hadn't run a proper simulation?'

'Common sense. This whole idea of throwing technology at problems created by technology... '

Maria felt her patience desert her. 'What would you rather do? Be humble in the presence of nature, and hope you'll be rewarded for it? You think Mother Gaia is going to forgive us, and put everything right-just as soon as we throw away our wicked computers and promise to stop trying to fix things ourselves?' Should have made that 'Nanny Gaia.'

Aden scowled. 'No-but the only way to 'fix things' is to have less impact on the planet, not more. Instead of thinking up these grandiose schemes to bludgeon everything into shape, we have to back off, leave it alone, give it a chance to heal.'

Maria was bemused. 'It's too late for that. If that had started a hundred years ago... fine. Everything might have turned out differently. But it's not enough any more; too much damage has already been done. Tip-toeing through the debris, hoping all the systems we've fucked up will magically restore themselves-and tip-toeing twice as carefully every time the population doubles-just won't work. The whole planetary ecosystem is as much of an artifact, now, as... a city's microclimate. Believe me, I wish that wasn't the case, but it is-and now that we've created an artificial world, intentionally or not, we'd better learn to control it. Because if we stand back and leave it all to chance, it's just going to collapse around us in some random fashion that isn't likely to be any better than our worst well-intentioned mistakes.'

Aden was horrified. 'An artificial world? You honestly believe that?'

'Yes.'

'Only because you spend so much time in Virtual Reality you don't know the difference anymore.'

Maria was indignant. 'I hardly ever-' Then she stopped herself, realizing that he meant the Autoverse. She'd long ago given up trying to drum the distinction into his head.

Aden said, 'I'm sorry. That was a cheap shot.' He made a gesture of retraction, a wave of the hand more impatient than apologetic. 'Look, forget all this depressing ecoshit. I've got some good news, for a change. We're going to Seoul.'

Maria laughed. 'Are we? Why?'

'I've been offered a job. University Music Department.'

She looked at him sharply. 'Thanks for telling me you'd applied.'

He shrugged it off lightly. 'I didn't want to get your hopes up. Or mine. I only heard this afternoon; I can still hardly believe it. Composer-in-residence, for a year; a couple of hours a week teaching, the rest of the time I can do what I like: writing, performing, producing, whatever. And they throw in free accommodation. For two.'

'Just... hold it. A few hours' teaching? Then why do you have to go there in person?'

'They want me, physically. It's a prestige thing. Every Mickey Mouse university can plug into the networks and bring in a dozen lecturers from around the world-'

'That's not Mickey Mouse, it's efficient.'

'Cheap and efficient. This place doesn't want to be cheap. They want a piece of exotic cultural decoration. Stop laughing. Australia is flavor of the month in Seoul; it only happens once every twenty years, so we'd better take advantage of it. And they want a composer-in-residence. In residence.'

Maria sat back and digested it.

Aden said, 'I don't know about you, but I have a lot of trouble imagining us ever being able to afford to spend a year in Korea, any other way.'

'And you've said yes?'

'I said maybe. I said probably.'

'Accommodation for two. What am I supposed to do while you're being exotic and decorative?'

'Whatever you like. Anything you do here, you could do just as easily there. You're the one who keeps telling me how you're plugged into the world, you're a node in a logical data space, your physical location is entirely irrelevant... '

'Yes, and the whole point of that is not having to move. I like it where I am.'

'That shoebox.'

'A campus apartment in Seoul won't be much bigger.'

'We'll go out! It's an exciting city-there's a whole cultural renaissance going on there, it's not just the music scene. And who knows? You might find some exciting project to work on. Not everything gets broadcast over the nets.'

That was true enough. Korea had full membership of ASEAN, as opposed to Australia's probationary status; if she'd been living in Seoul at the right time, if she'd had the right contacts, she might have ended up part of Operation Butterfly. And even if that was wishful thinking-the right contacts probably took a decade to make-she could hardly do worse than she'd been doing in Sydney.

Maria fell silent. It was good news, a rare opportunity for both of them, but she still couldn't understand why he was unloading it on her out of the blue. He should have told her everything when he'd applied, however poorly he'd rated his chances.

She glanced at the stage, at the twelve sweating musicians playing their hearts out, then looked away. There was something disconcertingly voyeuristic about watching them without tuning in: not just the sight of them emoting in silence, but also the realization that none of the bands could see each other, despite the fact that she could see them all.

Aden said, 'There's no rush to make up your mind. The academic year starts on January ninth. Two months away.'

'Won't they need to know, long before then?'

'They'll need to know by Monday if I've accepted the job-but I don't think the accommodation will be a big deal. I mean, if I end up alone in an apartment for two, it'll hardly be the end of the world.' He looked at her innocently, as if daring her to give the time and place he'd ever promised to turn down a chance like this, just because she didn't want to come along for the ride.

Maria said, 'No, of course not. How stupid of me.'

Home, Maria couldn't resist logging on to the QIPS Exchange, just to find out what was going on. Operation Butterfly had vanished from the market. Omniaveritas, her knowledge miner, had picked up no news reports of a typhoon in the region; perhaps the predicted one had failed to eventuate-or perhaps it was yet to appear, but the simulations had already given their verdict. It was strange to think that it could all be over before the storm was a reality... but then, by the time anything newsworthy happened, the actual meteorological data would-hopefully-bear no relationship at all to what would have happened if the weather control rigs had been in use. The only real-world data needed for the simulations was the common starting point, a snapshot of the planet's weather the moment before intervention would have begun.

The QIPS rate was still about fifty percent higher than normal, as ordinary users jostled to get their delayed work done. Maria hesitated; she felt like she needed cheering up, but running the Autoverse now would be stupid; it would make far more sense to wait until morning.

She logged on to the JSN, slipped on her gloves, activated the workspace. An icon of a man tripping on a banana skin, frozen in mid-fall, represented the snapshot of her interrupted task. She prodded it, and the Petri dishes reappeared in front of her instantly, the A. lamberti feeding, dividing and dying, as if the past fifteen hours had never happened.

She could have asked Aden to his face: Do you want to go to Seoul alone? Do you want a year away from me? If that's it, why don't you just say so? But he would have denied it, whether or not it was the truth. And she wouldn't have believed him, whether or not he was lying. Why ask the question, if the answer told you nothing?

And it hardly seemed to matter, now: Seoul or Sydney, welcome or not. She could reach this place from anywhere-geographically or emotionally. She stared into the workspace, ran a gloved finger around the rim of one of the Petri dishes, and declaimed mockingly, 'My name is Maria, and I am an Autoverse addict.'

As she watched, the culture in the dish she'd touched faded from muddy blue to pure brown, and then began to turn transparent, as the viewing software ceased classifying dead A. lamberti as anything more than chance arrangements of organic molecules.

As the brown mass dissolved, though, Maria noticed something she'd missed.

A tiny speck of electric blue.

She zoomed in on it, refusing to leap to conclusions. The speck was a small cluster of surviving bacteria, growing slowly-but that didn't prove anything. Some strains always lasted longer than others; in the most pedantic sense, there was always a degree of 'natural selection' taking place-but the honor of being the last of the dinosaurs wasn't the kind of evolutionary triumph she was looking for.

She summoned up a histogram showing the prevalence of different forms of the epimerase enzymes, the tools she'd been pinning her hopes on to turn mutose back into nutrose... but there was nothing out of the ordinary, just the usual scatter of short-lived, unsuccessful mutations. No hint of how this strain was different from all of its extinct cousins.

So why was it doing so well?

Maria 'tagged' a portion of the mutose molecules in the culture medium, assigning multiple clones of Maxwell's Demon to track their movements and render them visible... the Autoverse equivalent of the real-world biochemist's technique of radioactive labeling-along with something like nuclear magnetic resonance, since the demons would signal any chemical changes, as well as indicating position. She zoomed in on one surviving A. lamberti, rendered neutral gray now, and watched a swarm of phosphorescent green pin-pricks pass through the cell wall and jostle around the protoplasm in the sway of Brownian motion.

One by one, a fraction of the tags changed from green to red, marking passage through the first stage of the metabolic pathway: the attachment of an energy-rich cluster of atoms-more or less the Autoverse equivalent of a phosphate group. But there was nothing new in that; for the first three stages of the process, the enzymes which worked with nutrose would squander energy on the impostor as if it were the real thing.

Strictly speaking, these red specks weren't mutose any more, but Maria had instructed the demons to turn an unmistakable violet, not only in the presence of nutrose itself, but also if the molecules under scrutiny were rehabilitated at a later stage-salvaged in mid-digestion. With the epimerase enzymes unchanged, she doubted that this was happening... but the bacteria were thriving, somehow.

The red-tagged molecules wandered the cell at random, part-digested mixed with raw indiscriminately. Neat process diagrams of metabolism-the real-world Embden-Meyerhof pathway, or the Autoverse's Lambert pathway-always gave the impression of some orderly molecular conveyor belt, but the truth was, life in either system was powered by nothing at the deepest level but a sequence of chance collisions.

A few red tags turned orange. Stage two: an enzyme tightening the molecule's hexagonal ring into a pentagon, transforming the spare vertex into a protruding cluster, more exposed and reactive than before.

Still nothing new. And still no hint of violet.

Nothing further seemed to happen for so long that Maria glanced at her watch and said 'Globe,' to see if some major population center had just come on-line for the day-but the authentic Earth-from-space view showed dawn well into the Pacific. California would have been busy since before she'd arrived home.

A few orange tags turned yellow. Stage three of the Lambert pathway, like stage one, consisted of bonding an energy-rich group of atoms to the sugar. With nutrose, there was a payoff for this, eventually, with twice as many of the molecules which supplied the energy ending up 'recharged' as had been 'drained.' Stage four, though-the cleaving of the ring into two smaller fragments-was the point where mutose gummed up the works irretrievably...

Except that one yellow speck had just split into two, before her eyes... and both new tags were colored violet.

Maria, startled, lost track of the evidence. Then she caught sight of the same thing happening again. And then a third time.

It took her a minute to think it through, and understand what this meant. The bacterium wasn't reversing the change she'd made to the sugar, converting mutose back into nutrose-or doing the same to some part-digested metabolite. Instead, it must have modified the enzyme which broke the ring, coming up with a version which worked directly on the metabolite of mutose.

Maria froze the action, zoomed in, and watched a molecular-scale replay. The enzyme in question was constructed of thousands of atoms; it was impossible to spot the difference at a glance-but there was no doubt about what it was doing. The two-atom blue-red spike she'd repositioned on the sugar was never shifted back into its 'proper' place; instead, the enzyme now accommodated the altered geometry perfectly.