Harry Potter and the Methods of Rationality discussion thread, part 23, chapter 94

elharo

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 94. The previous thread has passed 200 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, 20, 21, 22.

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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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

was performed on a moving planet

Of course. This suggests that the spell uses something as a reference. If it’s the caster, then casting Aresto Momentum on a tree while riding the TGV will cause the tree to suddenly start moving at a few hundred km/s. If it’s the planet, casting it on an object inside the train will have the same effect. Wizards might not use fast vehicles a lot, but even the Hogwarts train and the flying brooms are fast enough to be very dangerous with heavy objects.

(That said, I don’t think there are any examples, in canon or MoR, of the spell being used for anything other than falling objects. If it only does that, then it’s much less dangerous in normal life, especially in a society without high-speed elevators, and it makes a bit more sense, though the name is even sillier.)

This is a great way of bringing a celestial body, e.g. Venus, on a transfer orbit which will put it in the same orbit as earth, but on the other side of the sun, as you'll only need to move the caster, not the planet itself. Such orbits are fairly stable on a human timescale, and colonization (plus terraforming) may begin then. Aiming the spell might be a little difficult, but is certainly doable (as amassed spell-casting will also do, there's no problem if several spells hit).

0Intrism13y

You could probably make Arresto Momentum relatively safe by having it choose between the caster's frame of reference and the earth's (at the caster's position) based on whichever results in the spell doing less work. It's still dangerous, obviously casting it on someone else's moving vehicle would be a bad move, but it avoids making anything go "zoom" in a privileged frame of reference.