Permutation City

Summary

And how a true "metaverse" comes into existence and the problems it faces as another part of the computational universe the people inhabit gathers more complexity, thereby competing for "reality" within that computational simulation.

But the general idea, of a computation that is running, independent of a substrate that it is running in, is truly the best part of this book. It's simply mind bending, in true Greg Egan style. Just like the idea in Blood Music is mindbending and utterly beautiful.