On the other hand, Harry doesn't seem to have said anything on physics that requires having read Barbour. Or have I missed it?
"Quantum mechanics wasn't enough," Harry said. "I had to go all the way down to timeless physics before it took. Had to see the wand as enforcing a relation between separate past and future realities, instead of changing anything over time - but I did it, Hermione, I saw past the illusion of objects, and I bet there's not a single other wizard in the world who could have. Even if some Muggleborn knew about timeless formulations of quantum mechanics, it would just be a weird belief about strange distant quantum stuff, they wouldn't see that it was reality, accept that the world they knew was just a hallucination. I Transfigured part of the eraser without changing the whole thing."
Other than the buzzword "timeless physics", this doesn't go beyond anything that I knew about in 1991 (when I was older than Harry but still in high school and had never heard of Julian Barbour). This is implicit in Minkowski's formulation of special relativity (1908) and Heisenberg's formulation of quantum mechanics (1925); I don't know who made it explicit, but I probably read about it in popular science books.
ETA: The buzzword that I knew then (or perhaps learnt later and immediately connected to what I knew then, I'm no longer sure) is "block universe".
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: