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drethelin comments on Harry Potter and the Methods of Rationality discussion thread, part 17, chapter 86 - Less Wrong Discussion

9 Post author: Alsadius 17 December 2012 07:19AM

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Comment author: drethelin 17 December 2012 09:49:29AM 8 points [-]

What percentage of "facts" Moody exposits to the audience/Harry do we think are false or misdirection? At the least, the comment about Avada needing to find a soul is out of line with Canon where it can be blocked by inanimate objects such as statues.

Also: I look forward to the inevitable Moody/Quirrel showdown/makeouts.

Comment author: FiftyTwo 17 December 2012 11:05:41PM 10 points [-]

Given Moody's CONSTANT VIGILANCE I wouldn't be surprised at him randomly dropping false information into conversations, especially with suspiciously skilled young wizards...

Comment author: J_Taylor 19 December 2012 03:45:40AM *  14 points [-]

Moody drops all sorts of information, true and false, in his conversations and, when meeting that person again, will see if they recall it.

This is one of the ways he tests for Polyjuice users, animagi, and evil twins.

Comment author: wedrifid 19 December 2012 07:58:06AM 7 points [-]

Moody drops all sorts of information, true and false, in his conversations and, when meeting that person again, will see if they recall it.

This is one of the ways he tests for Polyjuice users, animagi, and evil twins.

I hope he also tests for information that is true that he hasn't actually given and wouldn't expect them to have.

Comment author: Eugine_Nier 20 December 2012 02:56:05AM 2 points [-]

This is also a great technique for mapping out social networks, conspiracies, etc.

Comment author: DanArmak 21 December 2012 08:24:43PM -1 points [-]

evil twins.

In the Morverse, twins share a telepathic bond and are sort of the same person. Either both twins are good or both are evil.

Comment author: pedanterrific 22 December 2012 12:52:11AM 2 points [-]

Almost certain they aren't telepathic, they're just the same person. You don't have to be perfect rationalists to always agree, if you're irrational in exactly the same way, and have exactly the same information and priors.

Comment author: gwern 22 December 2012 01:04:06AM 1 point [-]

/not sure if DanArmak and pedanterrific are serious or just joking

Comment author: pedanterrific 22 December 2012 01:20:19AM *  1 point [-]

You don't get the Aumann references in all the Twins' POV sections? I'll go dig up some examples, then.

Edit: Here we are:

The brothers walked on and on and on, mostly in silence. The Weasley twins talked to each other when they were thinking through new pranks, or when one of them knew something the other didn't. Otherwise there wasn't much point. If they already knew the same information, they tended to think the same thoughts and make the same decisions.

(Back in the old days, whenever magical identical twins were born, it had been the custom to kill one of them after birth.)

In time, Fred and George clambered out into a dusty cellar, strewn with barrels and racks of strange ingredients.

Fred and George waited. It wouldn't have been polite to do anything else.

Before too long a thin old man in black pajamas clambered down the steps that led into the cellar, yawning. "Hello, boys," said Ambrosius Flume. "I wasn't expecting you tonight. Out of stock already?"

Fred and George decided that Fred would speak.

"Not exactly, Mr. Flume," said Fred.

Comment author: gwern 22 December 2012 01:34:58AM 1 point [-]

I got the Aumann references, I was questioning the claim that they are telepathic or the same person (both of which possibilities are damaged by that quote), or whether it was just a joke on the Aumanning.

(On a side note, that reminds me that we still haven't found out how the Skeeter prank was done. After pondering it and imagining myself to be Bruce Schneier, I figure it was an attack on the printer as the weakest link, possibly polyjuicing or otherwise impersonating the editor.)

Comment author: pedanterrific 22 December 2012 01:41:27AM *  1 point [-]

Oh well yes, the "same person" bit was a joking reference to that. I thought I made that clear with the second sentence. Oops.

And I always assumed, in the absence of evidence otherwise, that it was some mind manipulation of Rita and/or her editor- False Memory Charms, Confundus or Imperius- perpetrated by either Quirrell or Dumbledore.

Comment author: gjm 17 December 2012 11:56:53PM 9 points [-]

On the other hand, given his preference for not losing the war against Voldemort he might perhaps avoid dropping too much random false information on a suspiciously skilled young wizard who is credibly alleged to be vital for winning that war.

Comment author: MugaSofer 18 December 2012 07:57:12PM 1 point [-]

On the other hand, wouldn't most people already know something like that? It seems like a pretty baldfaced lie, crying out for contradiction.

Comment author: Manfred 17 December 2012 11:17:05AM 5 points [-]

Perhaps Dumbledore simply ensouled the statues.

Comment author: DanArmak 17 December 2012 12:03:08PM 4 points [-]

With the souls of his enemies, muhahaha.

Comment author: Manfred 17 December 2012 12:04:15PM *  13 points [-]

The ritual involves getting right up next to your enemy and making a loud sucking sound.

Comment author: DanArmak 17 December 2012 12:08:50PM 12 points [-]

Pansy now believes she won't be affected by Adava Kedavra, and wants to join the Death Eaters.

Comment author: Eliezer_Yudkowsky 18 December 2012 07:41:19AM 8 points [-]

This would be an awesome prank to play on Pansy using a green light spell.

Comment author: MugaSofer 18 December 2012 08:15:37PM 4 points [-]

That's ... kind of disturbing, actually.

Comment author: Manfred 19 December 2012 03:38:31AM 4 points [-]

Yeah, my mental model of Harry was going "AAAAAAAAH!"

Comment author: ChrisHallquist 17 December 2012 12:19:33PM 9 points [-]

My guess is that this was a deliberate change. I always thought "cannot be blocked, except by inanimate objects!" was kinda lame.

Comment author: Desrtopa 17 December 2012 05:33:14PM *  32 points [-]

Suddenly Quirrell's using it in the duel with Bahry is looking a lot weirder. What happens when he dodges it, does it go straight through the wall and keep on going indefinitely until it hits someone? Isn't that a massive liability since he risks someone seeing it, thereby giving away his presence?

Being able to be blocked by inanimate objects might seem "lame" for an epic forbidden spell, but being able to pass through solid matter like a jet of neutrinos turns it into yet another game-breakingly borkable element like the Bag of Holding. Combined with the Eye of Vance, Moody should mostly be able to avoid dueling in favor of sniping dark wizards through buildings.

This seems like an uncharacteristic failure by EY to think things through.

Comment author: Qiaochu_Yuan 18 December 2012 12:03:29AM 6 points [-]

Maybe it hits a Dementor and that's how they reproduce.

Comment author: TrE 17 December 2012 08:27:27PM *  2 points [-]

Moody would have to take into account the coriolis non-force, at least for very-long-range shots. How fast does a killing curse move? Also, to what amount is a curse affected by curved space? Do they react to gravity at all?

Comment author: DanielLC 18 December 2012 02:16:24AM 15 points [-]

It's not clear what it would mean to not be affected by curved space or gravity, since there's no "straight" besides geodesics and no "non-accelerating" besides freefall, but that doesn't seem to stop much in the HP verse.

Speaking of curved space, I've noticed that there are spells to make things bigger on the inside. If you do this just right, you can create a singularity known as a cone point that ought to send any spell fired at it back in the direction of the caster. Also, you could make a faster-than-light drive, which could be used as a time machine.

Comment author: TrE 18 December 2012 07:38:32AM 2 points [-]

If the inertial mass of a spell is greater than its gravitational mass, it would appear that the spell doesn't react to gravity as much as it should. It is also possible that spells work a bit like brooms.

Comment author: DanielLC 18 December 2012 08:32:32AM 2 points [-]

Gravity doesn't work that way. Something not reacting to gravity under general relativity is like something stopping under special relativity (or even Galilean invariance). However, considering that there's a spell that does just that, this doesn't mean much.

Comment author: Eliezer_Yudkowsky 19 December 2012 05:22:51AM 8 points [-]

I hereby declare Arresto Momentum to match the velocity of a small mass to the velocity of some much larger mass that the wizard thinks is a reference frame.

Comment author: MugaSofer 19 December 2012 12:32:43PM 6 points [-]

Does that mean Harry can't use it (becuse there is no universal reference frame) or he can use it in all sorts of munchkiny ways (I stop the car ... relative to the moon!)

Comment author: Eliezer_Yudkowsky 20 December 2012 12:29:54AM 4 points [-]

Well, for one thing, he's not powerful enough to cast it period, but if he were, I expect it would only work on near / nearest masses.

Comment author: shminux 20 December 2012 12:20:21AM 1 point [-]

munchkiny ways (I stop the car ... relative to the moon!)

That requires original research, like partial transfiguration.

Comment author: Alsadius 19 December 2012 09:37:41AM 2 points [-]

So what would it do with a wizard who had truly internalized the principle of relativity, and who understood that there was no privileged reference frame? Could he use it to de facto impart an arbitrary velocity to an arbitrary object?

Comment author: shminux 20 December 2012 12:28:15AM 0 points [-]

impart an arbitrary velocity to an arbitrary object?

You can equalize velocity of a given small object with that of the caster's reference frame. The excess momentum is transferred to the Earth (or potentially another massive body, though there is no proof that magic works outside the Earth's atmosphere, which incidentally means that the Pioneercrux may have decayed). This way there is no preferred reference frame.

Comment author: Kawoomba 19 December 2012 12:49:59PM 1 point [-]
Comment author: MixedNuts 19 December 2012 11:49:23PM 1 point [-]

You can't use Arresto Momentum for that; you need a much more massive object as a reference, but your reference frame only contains massless objects. I guess you could say that massless objects have much larger mass than other massless objects, and use Arresto Momentum to make photons go in arbitrary directions with negligible losses.

If you can make a surface cast a long-lasting Arresto Momentum, you have a near-perfect mirror for all wavelengths from radio to gamma and all angles. That would be useful. (Of course you can also make the light slower if you wish, but the fun you can have with arbitrary refractive indices with no wavelength dependence and no absorption is redundant here.)

Also, if we figure out the necessary ratio of masses at given magical energy, we can use the spell to measure mass. Assuming your aim is precise enough to Arresto Momentum a neutrino, anyway.

Comment author: TrE 18 December 2012 08:46:31AM 1 point [-]

Magic works like the author of the story wants it to work.

Comment author: Alsadius 18 December 2012 10:42:32AM 0 points [-]

I think it's safe to say that the HPMOR universe still runs on some sort of rules, even if they're not the usual ones Einstein taught us.

Comment author: MugaSofer 18 December 2012 08:11:31PM 3 points [-]

Actually, Eliezer has stated that he deliberately inserts impossible details in all his stories because he's disturbed by the notion that they might be simulated somewhere. I wouldn't expect it to affect the plot, though.

Comment author: ygert 19 December 2012 08:17:13AM 1 point [-]

Probably, but these are not mutually exclusive. If Dumbledore is right, the set of rules that the HPMOR world runs on are the laws of Narrative Causality.

Comment author: MugaSofer 19 December 2012 12:30:09PM -1 points [-]

You know that spell was invented for the film, right?

Comment author: DanielLC 19 December 2012 09:57:06PM 0 points [-]

According to the wiki:

Appearances Harry Potter and the Prisoner of Azkaban (First mentioned) Harry Potter and the Prisoner of Azkaban (film) (First identified as Aresto Momentum)

It looks to me like they established that there is a spell that does that, but it wasn't named until the movie. I suppose without the name there's no real evidence that it doesn't just accelerate the subject in any way the caster pleases.

In any case, in the MoR verse, the brooms act in a manner that involves some sort of rest state. Also, as of Eliezer's reply to this post, that spell canonically exists in the MoR verse.

Comment author: MugaSofer 19 December 2012 10:18:20PM 1 point [-]

Well, it's the name that actually tells us it's "arresting momentum" and not, I don't know, stopping him getting too close to the ground or some sort of anti-gravity spell. The scene is in the book, but the spell itself is not.

(The wiki treats the films a canon when they don't actually contradict the books, instead of a separate canon like most sane people would. They do the same for everything, in fact, from videogames to trading cards, although they draw the line at fanfiction.)

Comment author: MugaSofer 18 December 2012 08:09:56PM -1 points [-]

"Making things bigger on the inside" does not equal "bending space into any damn shape we please."

Comment author: DanielLC 18 December 2012 10:52:06PM 1 point [-]

A cone point only requires being able to make things bigger on the inside. Just make a series of concentric spheres that are the right amount bigger on the inside and outside. If you don't make it smooth, it won't be perfect, but it just has to be good enough.

I don't know much about the faster-than-light stuff. From what I can find, an Alcubierre drive needs at least some negative mass, which, from what I understand, would translate to having to make things smaller on the inside. It seems likely that wizards would be able to make things smaller on the inside too, and they just don't do it much because it's pretty useless, at least for things wizards would think of.

Comment author: MugaSofer 19 December 2012 01:19:54AM 0 points [-]

Good point on the spheres, although I think Extension Charms are tied to enclosed spaces (hell, they might not even bend space. They could tap into another dimension or move you "out of phase" or something.)

Regarding the FTL, Alcubierre drives need a ring (or donut in the latest designs) of negative energy (or matter, I guess.) I can see that translating into "smaller on the inside" constructions, although I doubt there's actually a spell for that (although you never know.) Might be able to transfigure the stuff, though.

Comment author: DanielLC 19 December 2012 02:00:07AM *  3 points [-]

I think Extension Charms are tied to enclosed spaces

Perhaps that's just because no wizard is well-versed in non-euclidean geometry well-enough to understand how it would work in a non-enclosed space.

Besides, enclosed is relative. Maybe light doesn't travel through it, but neutrinos and your enemy's spells do.

(hell, they might not even bend space. They could tap into another dimension or move you "out of phase" or something.)

It doesn't matter. As long as it takes longer to travel through, it works. For example, you could use different kinds of glass to make retroflectors using the same principle, since light will travel at different speeds.

although I doubt there's actually a spell for that (although you never know.)

Perhaps the same spell works. If the same spell could make something two or three times bigger on the inside, then why not one half times bigger?

Comment author: MixedNuts 19 December 2012 02:27:10PM 3 points [-]

What happens if you make it bigger on the inside and then turn it inside out?

Comment author: MugaSofer 19 December 2012 02:47:14PM *  -1 points [-]

Perhaps that's just because no wizard is well-versed in non-euclidean geometry well-enough to understand how it would work in a non-enclosed space.

Could be. Hard to tell without the author telling us.

Besides, enclosed is relative. Maybe light doesn't travel through it, but neutrinos and your enemy's spells do.

I think most spells are disrupted by solid objects. And most offensive spells would risk destroying whatever you charmed. Would be interesting to try it on something made of glass, though.

It doesn't matter. As long as it takes longer to travel through, it works. For example, you could use different kinds of glass to make retroflectors using the same principle, since light will travel at different speeds.

Oh, I see. Cool. I assumed they were purely theoretical.

Perhaps the same spell works. If the same spell could make something two or three times bigger on the inside, then why not one half times bigger?

Interesting point. I doubt it works by specifying the increase as a number, though.

Hmm, there are probably other uses for containers with shrunken insides.

Comment author: DanielLC 18 December 2012 02:12:03AM 0 points [-]

Perhaps it has a range limit.

Comment author: Desrtopa 18 December 2012 02:27:49AM 3 points [-]

It would have to be significantly shorter than a lot of other spells have been shown to be (able to engage in ground-to-air combat against brooms) to be unable to target a person inside a building from outside it, or for a very large building like the castle of Hogwarts, at least from several rooms away.

Ordinary sniping relies on large amounts of distance between the shooter and the target to prevent them from being noticed and avoided or attacked. Moody could just rely on having multiple walls between him and his target.

Comment author: MixedNuts 18 December 2012 12:05:16PM 0 points [-]

Seems pretty obvious that a Killing Curse can't hit anyone but the intended target. You don't want dead that bystander you're not thinking about. Also "I meant to kill someone else" would be a defense if arrested for it.

Given that, it can fade quickly once it's moved past the target.

Comment author: ArisKatsaris 18 December 2012 01:54:35PM 4 points [-]

Seems pretty obvious that a Killing Curse can't hit anyone but the intended target.

Hardly obvious to me.

You don't want dead that bystander you're not thinking about.

Just the mood is required to cast it, the "small crack" at the soul. A killing beam is then launched. The beam keeps going until it reaches a killable target, which it very clearly is then implied to kill.

I always find it strange when people are reading so many implications that clearly aren't there, and are denying the implications that are...

Comment author: [deleted] 18 December 2012 02:28:57PM 9 points [-]

I always find it strange when people are reading so many implications that clearly aren't there, and are denying the implications that are...

No doubt they feel the same way.

Comment author: Gastogh 18 December 2012 01:33:54PM 2 points [-]

I don't remember anything about the spell not being able to hit anything but the intended target, either in canon or the MoRverse. What's your source? Or, if there is no explicit source, what makes it "obvious"?

Comment author: MixedNuts 18 December 2012 01:37:26PM 1 point [-]

I just said. "You have to mean it", so it's odd that you could kill someone you didn't mean to. Even if you interpret it as "You have to want someone dead, not necessarily the same person", "if you're arrested for killing with it, there's no possible defense", and "I meant to kill the Death Eater, but I hit the bystander" is a possible defense. Also nobody ever mentioned collateral damage.

Comment author: Salvius 21 December 2012 07:35:36PM 2 points [-]

FWIW, "You have to want someone dead, not necessarily the same person" is essentially how "intent to kill" works in a legal sense. That is, the distinction between murder and manslaughter is whether, by your actions, you intended to kill someone; under the law, it doesn't matter whether the person actually killed was the person you intended to kill, or not.

Not that the rules of magic are necessarily modeled after modern US jurisprudence, but it might be that they both reflect a deeper moral concept.

Comment author: MixedNuts 21 December 2012 07:58:14PM 1 point [-]

What happens if Alice Attacker tries to kill you, and you try to kill her in self-defense, but end up killing Bob Bystander? The Killing Curse solves that one by having self-defense not count as intent to kill; does law do the same?

Comment author: Salvius 22 December 2012 07:19:05AM 2 points [-]

I think so (it's been quite a few years since my brief foray into law school). Let me do some quick Googling...

Yep, there it is: Looks like it may vary in different jurisdictions, but

a defendant’s right of self-defense "transfers" (just as intent to kill does) from the intended to the actual victim...If the defendant, acting justifiably in self-defense against an aggressor, fires a weapon "wildly or carelessly," thereby jeopardizing the safety of known bystanders, some courts hold the defendant guilty of manslaughter (or of reckless endangerment if no bystander is killed), but not of intentional homicide.

Comment author: Gastogh 18 December 2012 02:36:12PM 2 points [-]

Wanting to kill a specific person may be a requirement for fueling the spell, sure, but I don't see why that necessarily entails everyone else being immune to what is essentially a profoundly lethal effect. Once a bullet is in the air, it doesn't matter what motivated the firing of the gun.

The bit about nobody mentioning collateral damage sounds like an argument from silence. I'll tentatively grant you the point about "no possible defense", but to me it seems like Moody could well have been talking about deliberate, cold-blooded murder rather than all possible circumstances. I mean, by the time of the "no possible defense" line he's already name-dropped the Monroe Act, which is nothing if not a big, fat exception.

Comment author: Desrtopa 18 December 2012 01:53:22PM 1 point [-]

"if you're arrested for killing with it, there's no possible defense", and "I meant to kill the Death Eater, but I hit the bystander" is a possible defense.

Well if you were using it fighting Death Eaters under the Monroe Act, and accidentally killed a bystander, and had fellow aurors to back up your story, you probably wouldn't be arrested.

Comment author: Desrtopa 18 December 2012 02:01:28PM 0 points [-]

Well, in the original canon, Voldemort fires one at Dumbledore, and Fawkes catches it and is reduced to a chick (phoenixes being unkillable.)

Of course, evidence from the original canon doesn't suggest it being able to pass through solid matter either, so that doesn't mean a whole lot with respect to HPMoR, but the spell would have to fade pretty damn quick to not be a liability for being spotted through a wall after missing. If it does it sounds like the best suggestion so far for resolving Quirrell's use of it in Azkaban, but that still leaves Moody able to snipe people through buildings.

Comment author: DanArmak 21 December 2012 08:17:47PM *  1 point [-]

Well, in the original canon, Voldemort fires one at Dumbledore, and Fawkes catches it and is reduced to a chick (phoenixes being unkillable.)

So that's why Dumbledore set a chicken on fire - he was reviving Fawkes!

Comment author: MixedNuts 18 December 2012 02:19:24PM 0 points [-]

Sniper!Moody isn't a huge problem. Any halfway competent Dark wizard would plan for that kind of enemy (is the eye of Vance famous? anyway, anything that can help aim a Killing Curse through walls) and have wards in place to detect approaching and casting. It just makes walls transparent on both sides.

Comment author: Desrtopa 18 December 2012 03:31:06PM 2 points [-]

The Eye of Vance is well known enough that Moody was able to look it up and track it down, but not well known enough that he doesn't bother hiding facts such as its ability to see in a full sphere and through obstacles.

If wards can be put in place to detect approach with that kind of precision (evidence, the Marauder's Map, but that sort of thing may be beyond modern wizards, as it's part of Hogwarts' defense system and there's no other evidence of location scrying magic,) then you get an Avada Kedavra stalemate between Moody and anyone ensconced in a sufficiently well protected stronghold, but a complete mismatch between them and any of the vast majority of people who can't see through walls.

Considering that Moody was already a well known dark wizard hunter by the time he lost his eye, if the wielder can snipe people like this, it raises the question of how he got it from the person who had it in the first place. You'd expect a power hungry dark wizard to be able to use Avada Kedavra, and when you can actually see a full sphere around you through obstacles, it doesn't take a whole lot of creativity to notice that if you can use spells that go through obstacles, you can use it to attack people who can't see you.

Comment author: gwern 20 December 2012 06:27:33PM 4 points [-]

For context, the original backstory:

When Alastor Moody had lost his eye, he had commandeered the services of a most erudite Ravenclaw, Samuel H. Lyall, whom Moody mistrusted slightly less than average because Moody had refrained from reporting him as an unregistered werewolf; and he had paid Lyall to compile a list of every known magical eye, and every known hint to their location. When Moody had gotten the list back, he hadn't bothered reading most of it; because at the top of the list was the Eye of Vance, dating back to an era before Hogwarts, and currently in the possession of a powerful Dark Wizard ruling over some tiny forgotten hellhole that wasn't in Britain or anywhere else he'd have to worry about silly rules. That was how Alastor Moody had lost his left foot and acquired the Eye of Vance, and how the oppressed souls of Urulat had been liberated for a period of around two weeks before another Dark Wizard moved in on the power vacuum.

So, it cost the very experienced Moody a great deal, and that was him going all out ('silly rules'). I don't think we can rule out that the "powerful Dark Wizard" wasn't effectively employing the omniscience of the Eye.

Comment author: Desrtopa 20 December 2012 10:47:12PM 1 point [-]

Shooting someone with Avada Kedavra through a wall isn't going to result in the loss of any body parts though, and can be employed before face to face engagement is even an option, unless Moody had some way of teleporting straight into the wizard's stronghold, which would imply some pretty lousy security.

If the Eye of Vance lets you AK people through buildings, I wouldn't think the added security of having it would be worth enough to Moody to overcome the risk of trying to acquire it, which would probably be phenomenal unless whoever had it before was an idiot.

Comment author: gwern 20 December 2012 10:54:20PM 0 points [-]

Shooting someone with Avada Kedavra through a wall isn't going to result in the loss of any body parts though

It could be used to force other actions, per Quirrel's excuse to Harry, and the forced choices lead to limb loss.

Comment author: loup-vaillant 20 December 2012 06:11:33PM 0 points [-]

Moody can still dodge.

Comment author: MugaSofer 18 December 2012 07:58:40PM 0 points [-]

Seems pretty obvious that a Killing Curse can't hit anyone but the intended target.

That is not obvious at all, at least to me. Or Harry, who seemed to interpret it in terms of risk to bystanders.

Comment author: hairyfigment 18 December 2012 06:22:46AM -1 points [-]

"When" he dodges it? This seems like strong evidence that Q knew he wouldn't.

Combined with the Eye of Vance, Moody should mostly be able to avoid dueling in favor of sniping dark wizards through buildings.

An interesting point. Do we know that he doesn't, in cases where he wants them dead as an end in itself?

Comment author: Desrtopa 18 December 2012 06:50:37AM 1 point [-]

I'd be surprised if Quirrell isn't competent enough to be able to judge effectively if his opponent is going to be able to dodge his attack, and Bahry thought he was going to be able to dodge it. Killing a guard would be a bad idea (if he's still alive he can be obliviated without blowing a hole in their security,) so if the spell travels through walls it seems like a dumb move whether it hits or not.

We don't know for a fact that Moody doesn't snipe dark wizards through buildings, but if he did I'd think it would have been mentioned even with the small amount of stage time Moody's had so far.

Comment author: jsalvatier 22 December 2012 05:59:58AM 0 points [-]

Could be that the bolt just doesn't move that fast. If it's possible to dodge at close range (like Bahry?) then it would have to move fairly slow.

Comment author: Desrtopa 22 December 2012 06:14:31AM *  2 points [-]

Well, we don't know just how close they were, but if it were all that slow people wouldn't even bother using it in combat. I tend to assume that fired spells are somewhere in the ballpark of fastball speed.

A spell that can be dodged with difficulty when fired by an opponent you're dueling should be more than a little more difficult to dodge if it comes without warning out of a wall behind you though.

Comment author: syllogism 17 December 2012 04:44:04PM 6 points [-]

So if you fire it at the ground, can you kill someone on the other side of the Earth? Not being blocked by inanimate objects is kinda lame too.

Comment author: thomblake 17 December 2012 04:48:44PM 18 points [-]

Don't worry, the power drops off with the inverse square of the distance. It's lethal at pretty much any reasonable range, but then drops off quickly after a half mile or so.

I just made that up.

Comment author: Alsadius 18 December 2012 08:31:00PM 12 points [-]

Actually, it spreads as an Airy disc, which gives it a radius of about 300 metres at the far side of the planet, and the effect is divided among all the souls it hits. If you hit a city on the other side of the planet, you just take a couple days off everybody's life. (The technical term is "statistical homicide")

Comment author: FiftyTwo 17 December 2012 11:07:36PM 1 point [-]

That would make sense as a general rule for spells, otherwise why do they bother having duels face-to-face rather than sniping from nearby mountains? (Or an invisible broomstick 2000m up..)

Comment author: RolfAndreassen 18 December 2012 12:31:26AM 6 points [-]

You do have to aim it by hand and eye. You try hitting a human-sized target from a moving platform at 2km.

Comment author: Nornagest 18 December 2012 01:10:59AM *  7 points [-]

Given the descriptions of wandwork we've seen in canon and in MoR so far, I imagine it'd be difficult to reliably hit anything person-sized past thirty feet or so. You can't sight down a wand if you have to swish and flick (though a wizard's staff with a telescopic scope mounted on it is a nice Discworldly image), so it should be about as accurate as throwing a ball -- which is to say not very.

Comment author: FiftyTwo 18 December 2012 04:15:02AM 1 point [-]

We know of at least one spell that aims itself (Flitwick's) and area affect spells are possible (with a massive fireball it doesn't matter how you aim).

Alternatively, take a potion of +10 accuracy or the equivalent.

Comment author: Desrtopa 18 December 2012 07:17:28AM *  4 points [-]

Alternatively, take a potion of +10 accuracy or the equivalent.

Felix Felicis may be the only potion that performs that function, and it's sufficiently broken to be the Potion Not Appearing In This Fic.

Comment author: MugaSofer 18 December 2012 08:12:43PM 3 points [-]

Just find something that was made by using up a lot of accuracy. That should do it.

Comment author: linkhyrule5 22 December 2012 05:37:43AM 0 points [-]

A target with nothing but bulls-eyes will do.

Comment author: faul_sname 17 December 2012 05:15:25PM 4 points [-]

You would have to get extremely (un)lucky to do so. A human, lying down, takes up about 1 m^2 of space. Even if you fired it at a city with a population density of 10000 people/km^2, you'd still only have about a 1% chance of hitting someone (if you could even aim well enough to hit a city from 12000 km away).

Comment author: shminux 19 December 2012 12:17:21AM *  2 points [-]

Like an ordinary muggle missile, KC was designed with a built-in self-destruct mechanism, which is activated when its target is not hit. Thus you die if you block a curse aimed at someone else, but not if the curse misses the target and you happen to be in its path.

Comment author: ygert 17 December 2012 04:13:42PM 2 points [-]

This. If not this, Moody is lying, which is possible, as Moody is the type to keep information like that "in reserve", but I actually doubt that is the case, as sooner or later Harry would witness for himself a killing curse being cast, and would find that Moody had been lying.

Comment author: MugaSofer 18 December 2012 08:15:06PM 2 points [-]

Also, I doubt that everyone else in the room was either clueless or willing to let Harry receive such massively incorrect info.

Comment author: fubarobfusco 18 December 2012 02:00:27AM 7 points [-]

Moody/Quirrel showdown/makeouts

Moody♠Quirrell ... no, just no.

(Harry seems to have been through quadrant vacillation between Hermione and Draco, though. Hermione starts flushed for Harry, who doesn't reciprocate, so she goes pale instead to prevent him from becoming a Dark Lord. Harry♦Hermione seems pretty stable, although Harry has some pale infidelity with Draco — who briefly waxes caliginous before attempting to auspiticize between Harry and Lucius. After Draco drops Hermione, she tries to set up Harry♥Draco, not knowing that Draco has more ashen aspirations ....)

Comment author: Locke 18 December 2012 04:07:17AM 5 points [-]

Some of us are going to need a link explaining this system.

Comment author: fubarobfusco 18 December 2012 04:23:17AM 7 points [-]
Comment author: Alsadius 18 December 2012 05:28:59AM 10 points [-]

That, if anything, makes the system less clear.

Comment author: fubarobfusco 18 December 2012 08:03:49AM 1 point [-]

Okay, some explanation: I took drethelin's "showdown/makeouts" line to be an oblique reference to Homestuck, a long and rambling webcomic saga which prominently features a number of character relationships that might be described in such terms. If this assumption is false, the comment doesn't make much sense.

So I responded in terms of the "quadrants" used by Homestuck's troll characters to describe their romantic lives. There really isn't any simple explanation of these, but this is as good as any.

Comment author: MixedNuts 18 December 2012 12:27:19PM 9 points [-]

Yes there is a simple explanation.

Some relationships (♥ and ♠) involve intense, romantic, sexual passion, whereas others (♦ and ♣) are quieter, more reasonable, and closer to friendships and other platonic relationships. Also, some relationships (♥ and ♦) are based on positive feelings, whereas others (♠ and ♣) are based on negative ones.

♥ (violent positive) is passionate romantic love. ♦ (quiet positive) is deep platonic attachment. ♠ (violent negative) is a love/hate relationship. ♣ (quiet negative) is smoothing things over between a feuding pair.

Comment author: taelor 18 December 2012 08:09:11PM 1 point [-]

Point of order: the caliginous quadrant is not love/hate; it's all hate, but in a sexualized way. You have to genuinely dislike someone to be ♠ for them.

Comment author: MixedNuts 18 December 2012 09:30:31PM 0 points [-]

You mean that the one time I try to rely on how vague English is about feelings and just use "love" for "fascination, sexual tension, importance in one's life" it's not proper usage? That's it, I'm suing the Ingaevones.

Comment author: Alsadius 18 December 2012 08:40:35AM 2 points [-]

I've read that, and I'm no more enlightened. However, I approve of in-jokes, so I've taken away my downvote. Also, now I know that I should never, ever read Homestuck, so that's something.

Comment author: linkhyrule5 22 December 2012 05:26:43AM 0 points [-]

That's a shame. If there's one thing that Homestuck does right, it's time travel (and actually thinking through and writing what a world with casual time travel and timeline enforcement would look like.)

Comment author: Alsadius 22 December 2012 05:32:34AM 0 points [-]

Er, okay? That's not my objection.

Comment author: taelor 18 December 2012 12:33:39PM *  3 points [-]

This is a reference to the webcomic/multimedia series Homestuck by Andrew Hussie, which features a species of timetravelling aliens known as the Trolls due to fact that the first ones that the protagonists meet were actual internet trolls. The Trolls have their own wierd system of romance built around four quadrants: the flushed quadrant (denoted with a ♥) which loosly aproximates what humans think of as romantic love; the pale quadrant (♦) which is sort of an intense platonic friendship wherein one partner serves as a stablizing force on the other, more unstable partner; the ashen quadrent (♣) whereby one partner attempts to mediate between to otherwise violently opposed partners; and the caliginous quadrant (♠), which can be described as "romantic hate", and involve such things as "hatesnogging" and "murderfondling". A more detailed description can be found here.

It should also be noted that this thread already contains at least on reference to a Hussie creation (cousin_it's "HP: Punch AM in snout to establish superiority"), so it's likely that fubarobfusco was primed to interpret things in that light.

Comment author: MixedNuts 18 December 2012 01:03:47PM 6 points [-]

What do you mean, "no, just no"? Here are two extremely competent characters who will inevitably be pitted in full force against each other. They both respect competence in others (and likely relish a bit of a challenge), so they will necessarily admire each other, more and more as they get the measure of their respective power. They're not naive preteens drunk on their first slightly creative idea, they're adults with a lifetime of experience who know exactly how to have a rivalry. They'll never grow tired of playing against each other and they know that perfectly well. You will forgive me for shipping that just a little bit.

It's odd, being reminded that in the mainstream mentioning slash is on the level of potty humor, when in the world I normally inhabit you're supposed, on pain of being called a narrow-minded Philistine, to appreciate a story's literary value whether or not it's angsty porn in a setting based on dogs' social and reproductive habits where men get pregnant.

Comment author: fubarobfusco 18 December 2012 04:00:51PM 2 points [-]

Eh? I've nothing against slash, I just don't see Moody as having the time for that sort of thing. Shoot first and fantasize later, maybe ....

Comment author: MixedNuts 18 December 2012 05:03:07PM 5 points [-]

Moody makes time for every potential threat and for the occasional artifact hunt. You can argue it's not one of his priorities, but he's not exactly pressed for time should he so wish.

A much bigger problem is the inevitable distraction. He can have time-turned selves and possibly allies watching his back, his currently active enemies, and Quirrell's potential plots, but so can Quirrell. And there are probably more dark wizards who would benefit from Moody being distracted than the reverse. And is Moody even an Animagus? If not, or depending on his form, that's another advantage for Quirrell.

They could take an Unbreakable vow to abstain from shenanigans while on dates, but that's way too big a constraint for either to accept, doesn't stop third parties, and is probably full of loopholes.

Comment author: DanArmak 21 December 2012 08:28:45PM 0 points [-]

They could take an Unbreakable vow to abstain from shenanigans while on dates

An Unbreakable vow requires one party to sacrifice the possibility of freely trusting the other party. That's not a healthy relationship.

Comment author: MixedNuts 21 December 2012 09:50:06PM 0 points [-]

Sexual tension based on how fascinatingly brilliant each person is at trying to kill the other is rarely conducive to trust and healthy relationships. People are notoriously more tolerant of fucked up relationship dynamics under stressful conditions; a battle to the death with the world at stake would qualify.

Comment author: Qiaochu_Yuan 17 December 2012 10:15:22AM 2 points [-]

The comment about Avada being unblockable strikes me as Eliezer either not doing his homework or tweaking canon. If it were blockable in-universe Dumbledore would know this in addition to Moody (IIRC Dumbledore does one of the canon blocks) and would have pointed this out during the conversation (unless Dumbledore and Moody conspired beforehand to keep Harry ignorant of this for some reason, which, y'know, penalty for complexity).

Comment author: DanArmak 17 December 2012 12:03:46PM 1 point [-]

Doesn't everyone make a big deal about the Unblockable Curse being blocked by Harry in canon, too? Or is that just in HPMOR?

Comment author: Qiaochu_Yuan 17 December 2012 12:24:45PM 12 points [-]

Hmm. So Harry Potter Wikia seems to suggest that Avada is described as unblockable in canon, but what that seems to mean is that it isn't blockable by a shield spell or anything like that. Harry didn't exactly block it in canon; it hit him and he survived anyway because of the Power of Love. I'm updating mildly in the direction of Eliezer tweaking canon because he decided that the instances of Avada being blocked in canon were Rowling cheating.

Oog, now I'm semantically satiated on "block."

Comment author: MugaSofer 18 December 2012 07:38:04PM -1 points [-]

What percentage of "facts" Moody exposits to the audience/Harry do we think are false or misdirection? At the least, the comment about Avada needing to find a soul is out of line with Canon where it can be blocked by inanimate objects such as statues.

I've gotta say, that one threw me; it seems like the kind of thing that would have changed attitudes and usage of AK.