Harry Potter and the Methods of Rationality discussion thread, part 20, chapter 90

palladias

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:

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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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

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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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

Actually, most nuclear weapons get roughly comparable amounts of their force from fission and fusion, usually a little more from fission. Fission-only bombs are so much less powerful not because fission is but because they have very incomplete fission (around 1% for the Hiroshima bomb design, for example). The fusion reactions used in bombs produce a lot of excess neutrons, by design; all those neutrons flying around mean a lot more fission ends up happening. The only bombs that get most of their power from fusion are neutron bombs (which use a lot less fissionable material, and use the excess neutrons to increase the radiation damage) and clean bombs (which also use a lot less fissionable material, but replace it with lead to absorb the excess neutrons; clean is of course a relative term here).

The biggest difference as regards fission is that fusion bombs use U-238 as a power source, which is capable of releasing energy from fission, but which doesn't produce enough neutrons to sustain a chain reaction. But when fed excess neutrons from a fusion reaction, you get an immense energy release from a very cheap material that's used as the bomb casing.