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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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.

Whether this method works or not is up to the GM; the as-stated rule is that "information cannot go back more than six hours in time, using any combination of Time-Turners", which would allow this, but it's possible that anything which results in someone having more than 30 hours to a day is also bad. Granted, the hypothesis that 6 hours is the universe simulator's buffer size would suggest that this works.

It's a bit scary that if this scheme fails, there's no clean way for it to fail. In the very simplest case -- you go back in time 6 hours and then try to go back in time 1 more hour -- presumably the Time-Turner just doesn't work and nothing happens. Here, that outcome is not self-consistent: there's only one spin of the Time-Turner, and if it fails then there are no multiple Harry Potters so there is no reason for it to fail.

So if this scheme goes against the Time-Turner constraints, the only consistent outcome is that something unspecified happens to one of the first 6 Harry Potters to prevent them from getting back into the trunk. And summoning unspecified obstacles by the power of Time-Turner consistency seems like a really bad idea.

To fix this, we could have each Harry Potter toss a 100-sided die and leave the loop on a 1 being rolled; then run this algorithm several times. It's likely that spontaneous catastrophic failure has a probability much less than 1%, so the most likely consistent loop assuming this scheme doesn't work is one in which Harry rolls a 1 early on, which is very unlikely to happen assuming this scheme does work. So if several trials of this algorithm consistently keep ending after 1-6 repetitions, then it's almost certain that the universe doesn't like it.