It’s about people who upload their minds into a special simulation that once started from it’s initial state, the garden-of-eden configuration, will create an autonomous computer space, a computational universe disconnected from our own, where the human uploads live forever freed from intervention of the still embodied humans from Earth.
The thing about Egan is, he takes an idea and goes as far as anyone can think you could go with such an idea, and then he goes even farther, exploring all possible consequences, on the human level, the physics level, even the pure philosophical. At a time when you often hear people moan that there’s nothing really new under the sun and everything is just a variation of old themes, Egan comes to conclusions and insights in his novels and stories where you’re hard pressed to say it wasn’t new.
Point in case is Permutation City, it explores the concept of uploaded human minds more exhaustingly than ever before. It’s a breathtaking trip for people who value ideas and concepts, and an honest exploration of them that doesn’t flinch away from any conclusions it might reach. Pure mind expanding stuff, that also has a brilliant twist near the ending.