Harry Potter and the Methods of Rationality discussion thread, part 19, chapter 88-89

Vaniver

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 88-89. The previous thread has passed 500 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.

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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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

One of the established rules was that information can't be sent back more than six hours. Would he have broken time within six hours?

Also, there is always a way to head off a paradox. Consider the multiple universes model. What came out of the time machine in one universe is a function of what came out in the last universe. Furthermore, it's a continuous function. Theoretically, you could do something like send back what came out plus a mote of dust, but I think it can be assumed that there's a limit to whatever the time turner can bring back, meaning the domain of the function is bounded. Since every continuous function mapping a bounded set into itself has at least one fixed point, there must be at least one stable time loop.

Addendum: Why would it be a continuous function? Human decisions can be binary. Consider, as a trivial example, "If I see 1 on the paper, I'll write 0 and send it back in time. If I see anything else on the paper, I'll write 1 and send it back in time".

0Alsadius13y

Knowing HJPEV, yes, he would have broken time within six hours. He wouldn't have even had much trouble doing it. And yes, there's a stable time loop. It's the one where he writes "DO NOT MESS WITH TIME".