So, I don't know how these stable time loops are supposed to work. My working model is that they function by trial and error, that time iterates through a universe until it encounters paradox, at which point it returns to pre-paradox, inserts some change into the world through prophecy or whatever, and tries again. This continues until a stable timeline is found, with an unknown number of them being discarded/destroyed. It appears from within that things worked on the first pass, but they did not. Our viewpoint never follows into one of those dead ends, but they exist(ed).
If the world really works that way, Harry would be potentially throwing his victory away by forcing a paradox. Time would have to reset to before the paradox and insert a change into the world to ensure a different outcome. He may or not be victorious in that new timeline. Harry dying was already a high probability and it would certainly resolve things to Time's satisfaction. His best chance of securing his immediate past as part of the real and continuing world would be to make sure this timeline remains self-consistent.
(Plus, he's prophesied to destroy the stars and creating a time-paradox seems like a really obvious possible way to do that.)
The only other possibility I can think of for these apparently stable timelines is that the whole universe is pre-determined and no one has any free will at all. I read something from EY about universes with time travel and he seemed to be in support of this second possibility. Any other possibilities for how this would work?
I think that the trial and error model is implausible; in which "time" are these trials and iterations occurring? The global determination of the whole universe seems much simpler.
I don't think it necessarily conflicts with free will, when free will is understood in a compatibilist way (which is how EY and most LWers understand it). If we agree that one can have free will in a completely deterministic universe with ordinary past-to-future causal chains, then why can't one have it in a universe where some of the chains run future-to-past?
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 116.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)