Permutation City: Review

This is a spoiler-free book review of Permutation City. This book was written in 1994 by the Australian mathematician and writer Greg Egan. He has a very peculiar background, which is that of mathematics and programming. In mathematics, he is known for having solved a combinatorics problem. The problem is very easy to explain, there’s even this Quanta magazine article about it.

What is it about?

It is a fiction based on the theme of uploading one’s consciousness to a computer. In the near future, the technology now permits wealthy individuals to upload a scan of their brain with the initial conditions so that their brain activity can be simulated on the computer. This virtual copy running on the computer is now able to think and behave like the original, however the best computing resources will only be able to run the simulation at one-seventeenth the pace of the real brain.

Many characters in the book purely appear as copies living their life in a virtual environment with little interaction with the real world. The story also follows the plot of an Autoverse hobbyist, Maria. Autoverse is a cellular automata that exists only in simulation and behaves a bit like the real world but whose rules allow the formation of alternate biochemistries. Her life is changed forever when she meets an insurance broker, Paul. That is all I can say right now.

More than reading the story, reading the book is an experience in itself. Often the characters delve a lot on the philosophical implications of their intangibility, and wonder out loud over what they feel is real or not. The book is what is called hard science fiction, that is all technologies and science try to be highly believable and scientifically plausible. Such a detailed description of the scientific ideas involved kept me really hooked to the book. The philosophical quandaries that arise due in this fictional world feel like something that humanity may really have to encounter in the near future.

The book is likely to make one feel uncomfortable or unsure of what the human consciousness itself is. The entire idea of the consciousness seems to be deconstructed in the narration of this bizarre story. For me personally, reading this book created an excellent refuge away from my own personal life. Just like the characters in the book prefer to escape the real world circumstances by uploading their minds on a simulation, I feel that a reader can also benefit from a similar feeling of escapism by getting lost into this book.

Dust theory

An important part of the story is the idea which the author refers to as dust theory. I’ll try to explain it below.

When a person’s consciousness is inside a computer and if his world is completely cut off from the outside, there is no observation or experiment that will be able to tell the virtual mind how fast the computation is happening in the physical universe or how many parallel computations are taking to do it or even in what language or number system the calculations are taking place. At some point, the book points out that for a virtually conscious copy, it makes no difference even if the computations are being done on an abacus for millions of years. Pauses in the computation for any arbitrary duration in the calculations are also imperceivable to a copy unless it interacts with an outside world. It even makes no reason if the computation is actually being done or if the numbers are being read off from some memory parser. This makes the character Paul hypothesize that pausing the computation indefinitely will make no difference to a simulated mind, since the information needed for the computations to continue and the outcomes have already been written somewhere in the dust of the universe when the simulation begins. This idea is called the dust theory in the book.

As somebody pursuing mathematics myself, I do see why Greg Egan arrived at this conclusion. Often, while treating mathematical objects (computer calculations are also those), we start to believe that those things exist in their own universe in which they exist and interact with another like how we do with objects in our own. This third-person viewpoint makes us feel that mathematics is being discovered by us, just like how we might explore a city or poetry. Classically, this idea is known as the Platonic realism, or more specifically mathematical realism. From this point of view, it seems tempting to conclude that a computer program that was never started already has finished computation in some abstract form.

Getting lost in the narration

I really like stories where the commentary and the narration transcends the boundary of the fiction and start to play with perceptions of the audience. Many stories employ a calculated breaking of the fourth wall to achieve this effect, but the real players are those that create this effect in between the lines of the drama, by leaving hints for the careful members of the audience to pick those subtleties up. You will see that often the narration is from the point of view of a character existing virtually. His internal turmoils and ramblings are conveyed to the reader like how the reader might be familiar with reading their own turmoil.

In this sense, the characters feel truly conscious, even though the reader would have no idea where this consciousness is or what is the object that is doing the thinking. While reading the book, I was forced to accept that the narration is not just happening in a fictional timeline, but in some other universe entirely! But then, which narration happens in a timeline that we are familiar with. Like all fiction, we are supposed to waive our objections and believe that the universe presented exists. But to the extent where this liberty was taken in this book really throws the brain in a twirl!

The ending and the story of the book are maybe not as captivating as the thrill of this unique style of narration itself. All fiction is abstract, but this very unsettling feeling of reading a narration that is just mind-boggling and awesome. This book is completely breath-taking! In some sense, this book deconstructs the idea of what narration is.


Find this book and read it! If you have every written a computer program, thought about cellular automata, enjoyed doing and reading mathematics or just enjoyed watching The Matrix, there is a high chance that this book is for you. If nothing else, this book will make you forget the real world in these crazy times!