Unlike nukes, antimatter weapons can be made small enough yeild that you don't flatten the whole of hogwarts when you use one.

...but the amount of antimatter you'd use for that is very small indeed; about 0.000023 grams for an explosive yield equivalent to 1 ton of TNT, going by Wikipedia's numbers. I wouldn't put it past Quirrell to figure out a way to transmute quantities that small, but it'd be tricky; everything we've seen transmuted onscreen has been macroscopic.

Also, all the initial yield would be in the form of highly energetic gamma rays, so we'd likely be looking at something more like a hard radiation pulse than a bomb.

Hermione transfigured single walled carbon nanotubes

0skeptical_lurker5yDo wizards generally have a reason to transmute microscopic things? There's also the possibility of transmuting a larger portion of antimatter, levitated within a vacuum (bubble head charm maybe?) and then subdivde it, if that is possible.
0DanielLC5yYou could transmute something into something containing trace amounts of antimatter. Once the gamma rays hit something and get absorbed, they'll turn to heat. The bomb will make the floor explode.

Harry Potter and the Methods of Rationality discussion thread, January 2015, chapter 103

by b_sen 1 min read29th Jan 2015174 comments

7


New chapter, and the end is now in sight!

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 103.

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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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