Somewhat-credible conjecture: It is not possible for one Time-Turner to transport another through time. So when conductor Harry, carrying his trunk supposedly full of passenger Harries (Harrys?), flips his Time-Turner ... something bad happens. Maybe the others get left behind somehow, or the Time-Turner just doesn't work, or the universe ends, or something. Consequence: at least in any consistent branch of the universe, Harry fails to get his army of copies.
Edited for objection: Harry stashes the Time-turner in the Great Hall (for expository reasons).
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: