fantasy book reviews science fiction book reviewsGreg Egan Permutation City science fiction book reviewsPermutation City by Greg Egan

What would you give in exchange for immortality? Greg Egan‘s unabashed answer to that question in Permutation City is simple: Your humanity. Its sounds cliché, but Permutation City is a book that is able to do what only the best science fiction books can: make you think of questions you never knew you had, and imagine futures that seem ever more possible as time passes.

Around the mid-21st century, mind-uploading technology has been perfected, but its use is still limited to those few who can afford it. Moore’s law no longer holds, and computing power is an ever scarcer and costlier commodity, so much so that Copies without the requisite funds to run indefinitely are put on hold until the computing resources become available. Paul Durham has been trying to experiment on Copies of himself to uncover the underlying reality of artificial intelligence, but as soon as his Copies become ‘conscious’ they choose to terminate their own ‘lives’.

Determined to run his experiments, Durham does the unthinkable: He removes from his newest Copy’s software the choice to terminate its own ‘life’. Right away Egan presents us with questions on the issue of granting rights to artificial intelligence. While, as some have argued, Egan doesn’t explicitly dwell on those issues, the fact that we experience the viewpoint of the Copy, which is a perfect computational representation of Durham’s consciousness, gives us the necessary empathy to understand that the difference between a flesh and bone person, and an AI existing in the summation of electron probability clouds inside a computer is only in the materials with which they are made with. In fact that’s one of the themes Egan explores throughout Permutation City, that if human consciousness is capable of being computed, a Copy is as conscious as a person.

In one of the most interesting sequences of the novel, Durham runs the computations of the Copy’s mental states out of temporal order while we see through the Copy’s viewpoint that for itself time continues on as it has always had, illustrating beautifully the idea that subjective experience doesn’t depend on the permutations that give rise to it. It has been 32 years since Egan’s first published novel, so I might just be pointing out what everyone has already found out, but Permutation City has convinced me that Egan possesses immense skill when it comes to translate what would otherwise be abstract subjects into sequences that make clear the underlying complexity. That is not to say that Permutation City won’t sometimes go over your head, as Egan is writing about hard topics and assumes some knowledge of a lot of subject areas, e.g. computational theory, physics, and biology, but it is all presented in a way that is never any harder than it needs to be.

As we jump back and forth in time, we learn that, sometime in the future, Durham is trying to sell to Copies of millionaires who have already died the opportunity to not have to worry about having themselves wiped out from a backlash against Copies. The opportunity to, in essence, live forever. Initially Durham is suspected to be a mere con artist, since what he is selling would require computing power beyond what is currently available on the market, and even the brilliant Maria, whom he hires to work on his project, views Durham as a lunatic.

Incidentally, I found Maria the most interesting character on the whole novel, partly because she shares with the reader the same basic ignorance of what exactly is going on and what Durham’s vision is in a way that allows for our own questions to be asked through her voice. Also, because she is portrayed as an incredibly intelligent person who is normal in every other way, and not a recluse genius incapable of maintaining eye contact and having basic social interactions, which is a trope I’ve grown increasingly tired of.

Maria’s coding contracts have dried up, and her savings have dwindled to a precarious point, yet she can’t keep herself from spending her time and money buying the computational resources to enter the Autoverse, a complex cellular automaton able to simulate crude versions of real world physics and chemistry. Along with a few others, Maria is obsessed with showing that the complex rules of the Autoverse can support natural selection, modifying tiny segments of an artificial lifeform named Autobacterium lamberti in the hopes of obtaining a variation capable of showing signs of adaptation to its outside environment. We see early on Maria succeeding in her efforts, and the excitement her discovery creates inside the tiny circle of people who care about the Autoverse is enough to draw the attention of Durham, who hires Maria to create a seed, a set of initial instructions, which would in time create a world capable of sustaining life, albeit artificial.

Why would Maria agree to undertake such an immense project when both the details surrounding it, and the man who hires her, seem sketchy at best? Here is perhaps the one flaw I could find in the whole novel. Maria’s mother has cancer and refuses to have herself Copied, thinking it unnatural. Refusing to accept her mother’s wishes, Maria decides to earn the money needed to have her mother Copied before it’s too late, and Egan uses this, even though we never see any sort of familial attachment between both characters, to have Maria make decisions that she wouldn’t otherwise have made, advancing the novel’s plot to where it needs to go a bit too conveniently.

Permutation City has become a staple in transhumanistic circles, and it’s easy to see why. While we should be wary of conflating fiction for a serious possibility about the future, it’s hard not to ask oneself, “When are we going to see this coming true?” while reading Permutation City. It’s a serious book playing with interesting concepts, and while some of the questions it raises won’t become relevant for some time, the fact that artificial intelligence is a looming possibility warrants the need to think these questions through. Wholly recommended.

~Joao Eira

Permutation City by Greg EganPermutation City (1994) won the John W. Campbell Award and is probably Greg Egan’s best-known book. It is a very dense, in-depth examination of digital vs. physical consciousness, computer simulations of complex biological systems, virtual reality constructs, and multi-dimensional quantum universes. Yeah, pretty intimidating stuff. In fact, it was so over my head the first time I gave up in defeat. Then it started to bother me — such mind-boggling ideas were worth another attempt. So I listened to the book again and… I think I got some of it. The final third of the book is still beyond my comprehension, but the first two thirds present two carefully-described ideas that are worth examining — Dust Theory and the TVC universe. Piqued your interest? If so, read on.

Permutation City details attempts in the mid-21st century to create an artificial universe based in the Autoverse, a computer-generated environment where digital copies of wealthy people can enjoy a limited form of immortality in virtual reality. Most books would be content to go with that, but Egan is just getting started. Mysterious entrepreneur Paul Durham is pitching to aging millionaires a far-superior and more secure version of the Autoverse, and also hires solo programmer Maria to create a digital simulation of the early conditions on Earth that gave rise to life. He is stingy with the details, but Maria needs the money to help her ailing mother, so she signs on.

The only way for Paul to test the quality of the digital copies of his clients’ consciousnesses is to try it on himself. But each time he makes a copy, they choose to terminate themselves almost immediately. After numerous tries, he decides to remove their bailout option, forcing a copy of himself to remain “alive” and cooperate with him to further the project. This bears a superficial resemblance to Robert J. Sawyer’s The Terminal Experiment, but that book took the cheap Michael Crichton techno-thriller route, whereas Permutation City is exponentially more intelligent and ambitious.

During his experiments with his digital copy, he discovers that even if he rearranges the chronological order of distinct slices of the copies’ consciousness, his copy still experiences events in an internally-consistent way that defies expectation. There’s no was for me to explain it, other than to quote the text:

Now he was…dust. To an outside observer, these ten seconds had been ground up into ten thousand uncorrelated moments and scattered throughout real time – and in model time, the outside world had suffered an equivalent fate. Yet the pattern of his awareness remained perfectly intact: somehow he found himself, “assembled himself” from these scrambled fragments. He’d been taken apart like a jigsaw puzzle — but his dissection and shuffling were transparent to him. Somehow — on their own terms — the pieces remained connected.

Imagine a universe entirely without structure, without shape, without connections. A cloud of microscopic events, like fragments of space-time… except that there is no space or time. What characterizes one point in space, for one instant? Just the values of the fundamental particle fields, just a handful of numbers. Now, take away all notions of position, arrangement, order, and what’s left? A cloud of random numbers.

But if the pattern that is me could pick itself out from all the other events taking place on this planet, why shouldn’t the pattern we think of as ‘the universe’ assemble itself, find itself, in exactly the same way? If I can piece together my own coherent space and time from data scattered so widely that it might as well be part of some giant cloud of random numbers, then what makes you think that you’re not doing the very same thing?

Is your mind completely blown at this point? I had to read this through these passages several times, attempting to process them. Only by transcribing this was I able to grasp the idea. It may be completely outlandish, but I give Egan kudos for sheer daring. It is a variant of quantum mechanics, but goes a full step beyond that by postulating that the universe can and does take shape from pure randomness each and every moment of our subjective existence. What was he taking when he came up with that? I’m pretty sure I haven’t seen that in hard SF of the time, as this was written back in 1994!

He labels this bizarre concept Dust Theory, and this forms the foundations for an even more dazzling idea, that of the Turing-von Neumann-Chiang (TVC) universe. Again, this is subject matter enough for another book itself. The only way to explain this is to quote Egan again at length:

There’s a cellular automaton called TVC. After Turing, von Neumann and Chiang. Chiang’s version was N-dimensional. That leaves plenty of room for data within easy reach. In two dimensions, the original von Neumann machine had to reach further and further — and wait longer and longer — for each successive bit of data. In a six-dimensional TVC automaton, you can have a three-dimensional grid of computers, which keeps on growing indefinitely — each with its own three-dimensional memory, which can also grow without bound.


And when the simulated TVC universe being run on the physical computer is suddenly shut down, the best explanation for what I’ve witnessed will be a continuation of that universe – an extension made out of dust. Maria could almost see it: a vast lattice of computers, a seed of order in a sea of random noise, extending itself from moment to moment by sheer force of internal logic, “accreting” the necessary building blocks from the chaos of non-space-time by the very act of defining space and time.

By this point Egan had either excited computer science and quantum physics geeks into paroxysms of pure ecstasy, or driven liberal arts majors running screaming in the other direction. Initially I just couldn’t get it, but after transcribing it, I find it makes some sense if you accept the initial assumptions (a big if, of course). But believe it or not, this is still the halfway point of Permutation City, and things get EVEN MORE MIND-BOGGLING as it proceeds. The question arises of whether the TVC universe is infinite or will collapse from entropy as most theorists expect of our own universe. Paul Durham’s answer is:

The TVC universe will never collapse. Never. A hundred billion years, a hundred trillion; it makes no difference, it will always be expanding. Entropy is not a problem. Actually, ‘expanding’ is the wrong word; the TVC universe grows like a crystal, it doesn’t stretch like a balloon. Think about it. Stretching ordinary space increases entropy; everything becomes more spread out, more disordered. Building more of a TVC cellular automaton just gives you more room for data, more computing power, more order.


Ordinary matter would eventually decay, but these computers aren’t made out of matter. There’s nothing in the cellular automaton’s rules to prevent them from lasting forever. Durham’s universe – being made of the same “dust” as the real one, merely rearranged itself. The rearrangement was in time as well as space; Durham’s universe could take a point of space-time from just before the Big Crunch, and follow it with another from ten million years BC. And even if there was only a limited amount of “dust” to work with, there was no reason why it couldn’t be reused in different combinations, again and again. The fate of the TVC automaton would only have to make internal sense – and the thing would have no reason, ever, to come to an end.

In Part Two, the story jumps forward in time, to after the TVC universe, now commonly known as Elysium, has been created and six thousand years have passed internally. Moreover, the artificial life that Maria set the initial conditions of, called Autobacterium Lamberti, has gone through billions of years of virtual evolution using the unlimited computing power of the TVC universe, resulting in an entirely new intelligent species. They are insect-like, group-minded, and increasingly inquisitive about their world. However, they are unaware of the creators, humanity, or that their world was created by artificially.

As they start to investigate the founding principles of their world, Paul Durham and Maria become concerned that their experiments will threaten the fundamental principals of the TVC universe, due to a very byzantine thought process that suggests, to the best of my understanding, that it is the understanding of a given universe and its physical laws and properties that determine those laws and properties. So as the Lambertians begin to examine their world more closely, they are undermining the laws set in the Garden-of-Eden configuration. Here are some excerpts:

I think the TVC rules are being undermined — or subsumed into something larger. Do you know why I chose the Autoverse in the first place — instead of real-world physics? Less computation. Easier to seed with life. No nuclear processes. No explanation for the origin of the elements. I thought: in the unlikely event that the planet yielded intelligent life, they’d still only be able to make sense of themselves on our terms. It never occurred to me that they might miss the laws that we know are laws, and circumvent the whole problem. They haven’t settled on any kind of theory, yet. They might still come up with a cellular automaton model — complete with the need for a creator.


We can’t shut them down. I think that proves that they’re already affecting Elysium. If they successfully explain their origins in a way which contradicts the Autoverse rules, then that may distort the TVC rules. Perhaps only in the region where the Autoverse is run – or perhaps everywhere. And if the TVC rules are pulled out from under us…

What a fascinating question — what happens when the artificial life you’ve created starts to investigate its own origins? Will it guess correctly? Or make up its own explanations, religious or otherwise. Flipping the perspective from the created to the creator is just one of the many mind-expanding ideas that Egan seems to have in endless supply.

The end of the book involves Paul and Maria’s efforts to make contact with the Lambertians and convince them that they are indeed creations of humans, and that they should believe in our universe’s laws in order to maintain them. It was pretty difficult to follow this part, even after two listens, but if you could understand Dust Theory and the TVC universe, then perhaps this will make sense to you as well. My mind was somewhat overwhelmed by this point, but I can’t say for sure if it’s the fault the writer so much as my own ability to understand. While many books may have more entertaining characters or plots, Permutation City is one of the most ambitious explorations of digital consciousness, artificial life, and the fundamental assumptions behind our quantum universe that I have ever encountered. It’s not an easy read, but it will expand your mind.

Notes on the Audible version:

Just as he was for Quarantine, narrator Adam Epstein really is hopeless, especially his atrocious Australian, German, Italian, Russian, and Chinese accents. It would be one thing to do all those accents in the most stereotyped and insulting way possible, but he somehow manages to switch accents for the SAME CHARACTER mid-dialogue. It’s like a painful sketch on Saturday Night Live. Sometimes I was reduced to tears of laughter hearing how awful they were. It makes me wonder if he modeled his accents on the bad guys in action movies. He also regularly mispronounced words. Of the many cringe-worthy mistakes he made in this book, I laughed the most at his misreading of “causal structure” as “casual structure.” However, it’s not surprising that his audiobooks are just $1.99 each, but it’s really a disfavor to Greg Egan’s work. In the end, I’m sure I would have appreciated Permutation City much more if I had read the Kindle version (which is only $2.99). I still might not understand it, but at least I can do better accents.

~Stuart Starosta

Publisher: 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.


  • João Eira

    JOÃO EIRA, one of our guests, is a student at the University of Coimbra in Portugal, one of the oldest universities in the world, where he studies Physics and Economics. Having spent his formative years living in the lush vistas of Middle Earth and the barren nothingness in a galaxy far far away, he has grown to love filling his decreasing empty bookshelf space with fantasy and science fiction books. For him a book’s utmost priority should be the story it is trying to tell, though he can forgive some mistakes if its characters are purposeful and the worldbuilding imaginative. A book with no story can have no redeeming quality though. João probably spends more time fantasizing about books than doing productive things.

  • Stuart Starosta

    STUART STAROSTA, on our staff from March 2015 to November 2018, is a lifelong SFF reader who makes his living reviewing English translations of Japanese equity research. Despite growing up in beautiful Hawaii, he spent most of his time reading as many SFF books as possible. After getting an MA in Japanese-English translation in Monterey, CA, he lived in Tokyo, Japan for about 15 years before moving to London in 2017 with his wife, daughter, and dog named Lani. Stuart's reading goal is to read as many classic SF novels and Hugo/Nebula winners as possible, David Pringle's 100 Best SF and 100 Best Fantasy Novels, along with newer books & series that are too highly-praised to be ignored. His favorite authors include Philip K Dick, China Mieville, Iain M. Banks, N.K. Jemisin, J.G. Ballard, Lucius Shepard, Neal Stephenson, Kurt Vonnegut, George R.R. Martin, Neil Gaiman, Robert Silverberg, Roger Zelazny, Ursula K. LeGuin, Guy Gavriel Kay, Arthur C. Clarke, H.G. Wells, Olaf Stapledon, J.R.R. Tolkien, Mervyn Peake, etc.