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Permutation City is a 1994 science fiction novel by Greg Egan that explores many concepts, including quantum ontology, via various philosophical aspects of artificial life and simulated reality. It 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. The novel was also cited in a 2003 Scientific American article on multiverses by Max Tegmark.[1]

Themes and settingEdit

Permutation City deals with a question common in cyberpunk and postcyberpunk works: is there any difference between a computer simulation of a person and a "real" person? More specifically, Permutation City focuses on exploring one possible model of consciousness and reality, the Logic of the Dust Theory of reality, or simply Dust Theory, similar to the Ultimate Ensemble Mathematical Universe hypothesis proposed by Max Tegmark.

Like some other works of contemporary science fiction, it begins with the assumption that human consciousness is Turing computable: in other words, that all aspects of genuine consciousness can be produced by a computer program. Specifically, the book deals with some possible consequences of human consciousness being amenable to mathematical manipulation, as well as some possible consequences of simulated realities. In this way, Egan attempts to deconstruct not only some standard notions of self, memory, and mortality, but also of physical reality. Over the course of the story, Egan gradually elaborates the Logic of the Dust Theory of reality, the implications of which form the premise for much of the story's intrigue.

The story explores these ideas through a variety of avenues. One is that of the Autoverse, an artificial life simulator ultimately based on a cellular automaton complex enough to represent the substratum of an artificial chemistry. The Autoverse is a deterministic chemistry set, internally consistent and vaguely resembling real chemistry, but with only thirty-two elements and no nuclear analogue. In the novel, tiny environments, simulated in the Autoverse and filled with small populations of a simple, designed lifeform, Autobacterium lamberti, are maintained by a dwindling community of enthusiasts obsessed with getting A. lamberti to evolve, something Autoverse chemistry seems to make extremely difficult.

Another venue for these explorations is VR, virtual realities making extensive use of patchwork heuristics to simulate, crudely, completely immersive and convincing physical environments, albeit at a maximum of seventeen times slower than "real" time, the limit to the optical crystal computing technology used at the time of the story. Larger VR environments, covering a greater internal volume in greater detail, are cost prohibitive even though VR worlds are computed selectively for inhabitants, reducing redundancy and extraneous objects and places to the minimum details required to provide a convincing experience to those inhabitants, e.g. a mirror not being looked at would be reduced to a reflection value, with details being "filled in" as necessary if its owner were to turn their model-of-a-head towards it.

Within the story, "Copies", digital renderings of human brains with complete subjective consciousness, the technical descendants of ever more comprehensive medical simulations, live within VR environments after a process of "scanning". Copies are the only objects within VR environments that are completely mathematically internally consistent, everything else being the product of varying levels of generalisation, lossy compression, and hashing at all times.

Copies form the conceptual spine of the story, and much of the plot deals directly with the "lived" experience of Copies, most of whom are the survivors of wealthy billionaires suffering terminal illnesses or fatal accidents, who spend their existences in VR worlds of their creating, usually maintained by trust funds which independently own and operate large computing resources for their sakes, separated physically and economically from most of the rest of the world's computing power, which is privatised as a fungible commodity. In this way, Egan also deals with the socioeconomic realities of life as a Copy (the global economy of the novel is in recession and Copies often lose their vital assets), many of the less wealthy of whom live in "the Slums", a euphemism for the state of being bounced around the globe to the cheapest physical computing available at any given time in order to save money.

Many such lower-and-middle-class Copies exist at considerable "slowdown" relative to "real" time or even optimum Copy time, in order to save further money by allowing themselves to be computed momentarily from place to place and saved in suspension for cheap in the meantime. Through this, the concept of solipsism is examined prominently, with many lower-and-middle-class Copies attending social functions called Slow Clubs, where socialising Copies agree to synchronise with the slowest person present. Many of these lower/middle-class Copies become completely deracinated from their former lives and from world events, or else become Witnesses, who spend their time observing (at considerable time lapse) world events unfold, at the cost of any meaningful relationships with their fellow Copies. A subculture of lower/middle-class Copies, calling themselves "Solipsist Nation" after a philosophical work by their nominal founder, choose to completely repudiate the "real" world and any Copies still attached to it, reprogramming their models-of-brains and their VR environments in order to design themselves into their own personal vision of paradise, of whatever size and detail, disregarding slowdown in the process.

Further Egan novels which deal with these issues from various other perspectives include Diaspora and Schild's Ladder.


The plot of Permutation City follows the lives of several people in a near future reality where the Earth is ravaged by the effects of climate change, the economy and culture are largely globalised (the most commonly used denomination of currency is the ecu, from the word ecumen, a Greek root meaning 'the inhabited world'), and civilisation has accumulated vast amounts of ubiquitous computing power and memory which is distributed internationally and is traded in a public market called the QIPS Exchange (QIPS from MIPS, where the Q is Quadrillions).

Most importantly, from the perspective of the story, this great computing capacity is used to construct physiological models of patients for medical purposes, reducing the need for actual medical experimentation and enabling personalised medical treatments, but also enabling the creation of Copies, whole brain emulations of "scanned" humans which are detailed enough to allow for subjective conscious experience on the part of the emulation. Although not yet in widespread usage, scanning has become safe enough and common enough to allow for a subset of wealthy or dedicated humans to afford to create backups of themselves, generally with the intention of surviving the biological deaths of their bodies.

A minority of Copies exist, though they are largely perceived (with some justification) as being a collection of the thanatophobic eccentric rich. Copies do not yet possess human rights under the laws of any nation or international body, although a subgroup of the wealthiest Copies, those still involved with their own estates or businesses, finance a powerful lobby and public relations effort to advance the Copy rights cause. To this effect, the legal status of Copies is viewed as somewhat farcical even by sceptics of the cause, and many expect full Copy rights to be granted in Europe within two decades.

The plotline travels back and forth between the years of 2045 and 2050, and deals with events surrounding the life of a Sydney man named Paul Durham, who is obsessed with experimenting on Copies of himself (because he believes Copies of himself should be more willing to undergo experimentation). In the latter time frame, Durham is revealed to be, apparently, a con artist of some type, who travels around the world visiting rich Copies and offering them prime real estate in some sort of advanced supercomputer which, according to his pitch, will never be shut down and will be powerful enough to support any number of Copies in VR environments of their own designing at no slowdown whatsoever, no matter how preposterously opulent those environments might be.

He pitches this concept to the Copies, predicated upon the prediction that the Copy rights movement might run into resistance due to devastating climate change. As the world undergoes increasingly extreme and erratic weather, a variety of international bodies, especially the Association of Southeast Asian Nations, which has been particularly hard-hit by tropical storms, have proposed projects to use their vast computing resources to attempt to intervene, utilising chaotic effects to their advantage, in global weather patterns with such precision as to minimise weather-related destruction while also minimising the scale of the efforts necessary to do so. Durham predicts this will clash with the spread of Copy rights, as both Copies and weather simulations will demand increasing QIPS Exchange shares in the future. All that each Copy must do is to make the laughably small investment of two million ecus in order to bring Durham's fantasy computer into existence.

As part of his plot, Durham hires Maria Deluca, a nearly destitute Autoverse enthusiast, recently mildly famous for developing a variety of A. lamberti which evolved the capacity to metabolise an Autoverse toxin, and pays her six hundred thousand dollars to design an Autoverse program which, given a large enough computer, could potentially evolve into a planet bearing Maria's own strain of evolvable Autoverse life. Since no such computer exists, Durham attempts to convince Maria that he is a wealthy Autoverse enthusiast interested in her evolvability results and looking for a proof of concept for a much larger system. He also clandestinely commissions a famous virtual reality architect, Malcolm Carter, to build a full scale, high resolution VR city, Permutation City, the largest VR environment ever conceived, complete with reactive crowds and a staggering variety of full scale, high resolution scenic views.

As computer fraud investigators begin to close in on Durham's scheme, Maria becomes implicated and is pressed into covertly gathering evidence in order to incriminate Durham; however, she comes to doubt her commitments as she learns more about Durham himself, including his time spent in psychiatric care and his callous experimentation on his own Copies, as well as his assiduously reticent Copy backers.

Meanwhile, two Slum-dwelling Solipsist Nation Copies, Peer and Kate, explore their post-human existences as well as their strained but loving relationship, until Kate's long-time friend Malcolm Carter offers to secretly hack them both, along with any moderately-sized software packages they wish, into Permutation City's machine code, guaranteeing them a place in the city were it ever to run, but permanently debarring them from manipulating the city's implementation for fear of being deleted as extraneous cruft by automated software.

At the end of Part 1, Durham reveals his true intentions to Maria: by taking the earlier experiments to their logical end convinced that a thread of subjective consciousness can emerge from anywhere in the universe and continue without a physical computer to process it, Durham is staging a massive buyout of the world's processing power to simulate several seconds of a "Garden of Eden" configuration of an infinitely-expanding cellular automaton universe. He hoped that by his "dust theory", the simulation would subjectively persist independently without computer time, cut off from the known universe. His and his investors' copies would live forever in the simulation, and since the space of the simulation was made of self-reproducing cellular-automata computer processors, the simulation would not possess a mere finite number of states and the passengers wouldn't grow bored.

Durham had a long history of mental illness; he believed that he was a Copy but couldn't be sure. After he was pronounced cured, his condition was compounded by experimentation- by copying and remerging his consciousness until he couldn't tell whether he was real or a simulation. Obsessed with proving who he was, he hoped that even if his "dust theory" was incorrect, in the few seconds of simulation his copy would observe that his universe was in a Garden of Eden configuration that could not possibly have originated on its own, it had to be assumed as part of a simulation, and his copy would finally know who he was.

After a successful launch and simulation of the seed universe, Durham makes love with Maria and later that night disembowels himself with a kitchen knife, satisfied that he had passed on a satisfactory legacy for his Copy.

Part TwoEdit

Maria wakes in Permutation City 7000 years of subjective time after the launch, furious at Durham for being awoken and refusing to believe that the launch was successful. Durham quickly persuades her, however, and she begins to study the history of the Planet Lamberti, the autoverse simulation that she had started and that had been running on Permutation City infrastructure for billions of years of Autoverse time. Intelligent life in the form of complex swarms of insects has evolved on Lamberti from Maria's original Autobacterium hydrophilus.

The citizens of Permutation City were on the verge of making contact with the intelligent life that had evolved on Planet Lamberti. However, a town hall vote restricted the Autoverse scholars from making contact until the insects had independently hypothesized the existence of a creator.

Durham confides in Maria that he doesn't believe the insects will ever seriously consider the concept of a creator and intends to use her slice of the universe's processing power (as a founder of the world she was given de facto control of a continuously-growing zone of the processor network) to make forbidden first contact with the life of Planet Lamberti. He believes this is necessary because he's no longer able to freeze the Autoverse simulation or slow it down past a constant multiple of the size of the processor network. Durham is worried that the rules of their simulated universe are breaking down.

What he doesn't realize is that the intelligence of Planet Lamberti has exceeded the complexity of their own world, and that Lamberti has ceased to be defined as their simulation- Permutation City is now defined in terms of Autoverse physics rather than the other way around. That's why they were unable to interfere with the Autoverse simulation- its laws were inviolate now, not the cellular automata processor-network's laws. Shortly after failing to convince Planet Lamberti of the creator theory, the insects discover a set of field equations with a stable solution for each of their universe's elements; furthermore, initial studies on the equations show that they predict the spontaneous instantiation of matter at high temperatures.

To the citizens' alarm, Permutation City and eventually the entire processor-network begins to collapse into nothingness. Their processor network is no longer necessary to the existence of the Autoverse; there is a better solution that has superseded it, rendering the processor network literally nonexistent. This is a kind of reverse ontological argument: rather than the subjective, conscious necessity of God virtually creating him, his non-necessity destroys him- in this case the citizens of Permutation City. As Permutation City collapses, Durham creates a new Garden of Eden configuration and prepares to launch it in the processor network's last few seconds as a means of escape for Maria and the other founders, though he initially declines to board it himself. In the final moments, Maria convinces him to change his mind (literally reconfiguring it to desire escape) and together they leave, pledging to discover the underlying rules that governed the Autoverse's takeover of Permutation City.

See alsoEdit

External linksEdit

es:Ciudad Permutación fr:La Cité des permutants

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