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 109.
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.)
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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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.
Hypothesis: The mirror (or the whole room) connects universes. More specifically, there is only one mirror, stable in the multiverse (quantum, mathematical, magical or whatever) of compatible universes. A compatible universe is such an universe where the mirror exists, i.e. most probably the one that did not branch off before the end of Atlantis (or boltzmanned into existence a moment ago).
Looking into the reflection, your (magical) brain picks the image from a different universe, the one that matches your CEV most closely.
Nothing can hurt the mirror, unless the measure of the universes the action is performed in is a "significant portion" of the multiverse - otherwise it just dissipates.
The map shows gibberish, because, well, there is everybody and nobody in the last room...
+1 for using 'Boltzmann' as a verb.