Harry Potter and the Methods of Rationality discussion thread, part 20, chapter 90

palladias

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 90. The previous thread has passed 750 comments.

There is now 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.)

The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18,19.

Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:

You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).

If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.

Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:

You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).

If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.

I'd be very disappointed if this were actually plot relevant. The only hint that this might be where we're going is in Chapter 14 and that rules it out:

You know right up until this moment I had this awful suppressed thought somewhere in the back of my mind that the only remaining answer was that my whole universe was a computer simulation like in the book Simulacron 3 but now even that is ruled out because this little toy ISN'T TURING COMPUTABLE! A Turing machine could simulate going back into a defined moment of the past and computing a different future from there, an oracle machine could rely on the halting behavior of lower-order machines, but what you're saying is that reality somehow self-consistently computes in one sweep using information that hasn't... happened... yet..."

Ironically Harry is wrong about this. In point of fact his world is a simulation, as are all novels and fictional universes (though I have to consider the possibility that Harry's world is still not Turing computable. We don't yet have an existence proof of a computer program that can write fiction.)

What we see of Harry's world is a simulation and therefore (given a bunch of plausible hypotheses) computable. It doesn't follow that there is any "completion" of Harry's world, filling in all the stuff we don't see, that's computable, still less that there's any "reasonable" completion with that property. So I'd be hesitant to say that Harry's world, simpliciter, is a computable simulation.