The cover of Permutation City

Permutation City

by Greg Egan

As opposed to other hard sci-fi books (like The Freeze Frame Revolution), Permutation City does an excellent job of bringing the particularities of his world-building to bear on his characters and story. There’s a few nested concepts to explore: what would it feel like to be cloned? Does the infinite expanse of the universe guarantee all possible worlds are equally real? Is there any difference between living in a simulation and running the simulation?

The story of Permutation City took a while to really get going, and there were some concepts (the TVC cellular automata, specifically) that I couldn’t fully grasp. But overall, further proof that Greg Egan has a grasp on what makes hard sci-fi great.