Update: Discussion has moved on to a new thread.
The load more comments links are getting annoying (at least if you're not logged in), so it's time for a new Harry Potter and the Methods of Rationality discussion thread. We're also approaching the traditional 500-comment mark, but I think that hidden comments provide more appropriate joints to carve these threads at. So as of chapter 67, this is the place to share your thoughts about Eliezer Yudkowsky's Harry Potter fanfic.
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: one, two, three, four, five, six. The fanfiction.net author page is the central author-controlled HPMOR clearinghouse with links to the RSS feed, pdf version, TV Tropes pages, fan art, and more, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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.
The kind of simulation that Harry is in (that is, a piece of fiction) is admittedly not one where the initial conditions are established and it is calculated forward from there, such that X2 rather than X1 happening at time T1 necessitates Y2 rather than Y1 happening at time T2.
So, agreed, editing the chapter that describes T1 from X1->X2 doesn't necessarily cause evidence (e.g., Harry's memories) of X1 at T2 to change, so in principle he could notice the difference.
Which would in and of itself be a useful piece of information about the nature of the universe, I guess. He'd know that his perceived present is not in fact contingent on his past, but is instead separately created by some sort of external creator, who for whatever reason creates the illusion of such contingency.
As a literary choice, I disagree about its awesomeness... this kind of narrative self-reference is good for a kick-in-the-head, but it's difficult to maintain any kind of worthwhile narrative thereafter.
Then again, EY has already devoted many many words to the idea that a set of values can be both arbitrary and worthwhile, so perhaps he'd relish the challenge of writing a compelling Harry aware of his own fictional nature and constructing a meta-ethics that can survive that awareness.
Perhaps he'd also become aware of himself as a derivative work from a canon character who is less intelligent, rational, less powerful, and less American.
Anyway, like you, I doubt it's going to happen. That said, if anyone in that world has that awareness right now, it's Dumbledore, who is at the very least aware of the power that narrative tropes have in his universe.
I'm reminded of Sophie's World. The notion of writing SW fanfic in which Sophie, at the end of that book, finds herself in some SW fanfic is itself kind of amusing.
Metafiction.