If I remember correctly, Permutation City is more about the implications of modal realism (or "dust theory" in the book). Consciousness upload is used in the book to enter a simulated reality, but in itself that doesn't explain what happens when the simulation is turned off.
It does actually, and I really like this explanation: So, imagine you model a human mind. Now you can slow this model down, speed it up, the human mind does not know. In the novel states of the mind in time are computed, out of order, while watching reality, the mind observes it is time scambled but the mind itself does not notice. On the basis Egan concludes that the pattern that forms the mind may well be present in the universe somewhere, and the next time pattern, one time instance further may be somewhere completely different. But the mind does not notice. So the mind can just exist without it's physical basis being anywhere specifically... It get's one thinking.
Honestly as the other response says, indeed there is a parallel universe part to it.. For which I didn't really understand it relation to "dust".
I also liked "Quarantine" which made Quantum Mechanics somehow more intuitive to me. Truly a great writer.
> Honestly as the other response says, indeed there is a parallel universe part to it.. For which I didn't really understand it relation to "dust".
The other universes count as part of the "dust".
The characters in the book thought it would be only random 'simulations' that accidentally happen sometime in the universe's infinite future that kept running them -- that is, literal dust.
They were wrong. Simulations in entirely disjoint universes also count, and aren't nearly as predictable.
There's a fairly simple explanation, when you think about it.
They arranged to have the simulation in our universe turned off, but not to have all simulations turned off -- there's no way they could do the latter. So they ended up in a simulation run by someone who'd started off by simulating Earth, and who -- more likely than not -- were especially interested in embedded simulations.
Embedded simulations like theirs, but also like the Autoverse, and whoever it is was interested enough that they'd violate the simulated physics of Earth to keep simulating the cellular automaton despite the physics of Earth saying it should be shut off.
Viewed from that perspective, the ending is... not predictable, exactly, but at least plausible.
I would also recommend Charles Stross' Accelerando for an interesting take on the post-singularity universe where "others" can be in control of the simulated worlds. Sorry for the limited details, but I do not want to spoil the ending for others.
