Permutation City

This is undoubtedly one of the best books I have ever read. One of the knockdown Christian arguments for the existence of god is that of the first mover; as it goes “effect requires cause / since the universe is in motion, it must have had a cause / therefore god.” Of course, this argument merely passes the buck — if the universe can't be started in motion, why can god? What was his mover? Permutation City is what happens when you bite the bullet and take that question seriously.

This book follows a computer-simulated psychonaut in his quest to understand the nature of consciousness and reality. Egan really takes his time exploring the consequences of being able to make simulated copies of humans — for example, what happens if you run their subjective experience backwards? Or if you remove a haunting memory? Are two indistinguishable copies the same person? Amazingly, every result here is both coherent and interesting, and I found myself pausing every few pages to think deeply about the consequences of some aspect of Permutation City's reality. Egan is a mathematician, and it shows.

Go read this book. If you appreciate hard science fiction and remarkably good world-building, you will love it.