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.
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?
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.
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.
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.
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.
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!)
Now I come to think, he would probably just conclude it uses Earth as a reference frame, just as broomsticks use Aristotelian physics and transfiguration uses form/substance duality.
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.
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?
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.
Of course there’s no proof, but I don’t think it’s really possible, if only for literary reasons, that the Sphere of Stars spell is just a fancy hologram. I think we can take that as fairly strong evidence it’s working as intended.
So “arbitrary” might be a bit strong, but what’s to prevent him from using the Moon or the Sun as a reference frame? Or even the Earth as a whole, instead of the local part? Even imparting a relative 1000 mph to an object near the equator would be pretty powerful.
Just saying that if the spell is designed to work relative to the rest frame, then no amount of relativistic internalizing will change how it works. Of course it is possible in the HPMOR universe to design new spells, and a competent Wizard with a good grasp of invariance in physics might be able to create a new spell, Attache Momentum.
You are right, he did phrase it this way, which makes this spell unreasonably easy to munchkin. He would have probably thought harder about it were he a DM of an actual DD game.
It seems like a hack of the rules on the level of partial transfiguration. Also, if you house-rule that it requires “magical energy” in proportion to the delta-momentum, it shouldn’t be too overpowered.
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.
Didn’t he say that he mentioned the time-turner because it disproves the simulation hypothesis? It would also guarantee that nobody would simulate it.
He seems to have figured out how to simulate it later, but that requires simulating everything, and there’s no guarantee that there will even be a reality with a stable time loop, unless you have the infinite number of realities necessary to allow connectedness, in which case you can’t possibly simulate all the possibilities.
Actually, there is a guarantee that there will be a stable time loop. Look up the Novicov Consistency Principal some time. And I think that was to stop people speculating that magic was being provided by the Matrix Lords, although sadly it doesn’t. I was referring to the corridor tiled with pentagons (although it never actually says they were regular pentagons) and the spiral staircase that lifts you by rotating.
The Novicov Consistency Principal relies on the Kakutani fixed-point theorem, which relies on convexness, which implies connectedness, which implies an infinite number of realities.
I admit I’ve never seen a proof of the Novikov Consistency Principle. I know that’s how I’d prove something like that, and I know I could easily come up with a case of time travel with no possible stable time loop of I’m given a discrete space, a non-compact space, etc.
Sorry, I cannot find a link, but feel free to ask what does not make sense. As for the stable time loop, I’m not sure that it is always possible to find, given that you apparently want to fix both initial and final conditions of a hyperbolic PDE, unless I misunderstand what is involved in constructing such a loop.
But if you had done such arduous research as, say, reading the Wikipedia page for the NCP, you would see that a sum over histories using only non-paradoxical timelines apparently works. Not that I really understand that in more than a superficial way, but it sure as hell sounds like an answer to your point.
There are only guaranteed to be non-paradoxical timelines if you have an infinite number of realities, which is what I was saying from the beginning.
You could look for all the timelines that are within delta of being a paradox. I think the shadowing theorem guarantees that, for small enough delta, this is epsilon-close to a non-paradoxical history. I don’t think it tells you what delta is, and I don’t think it’s guaranteed that every non-paradoxical history will be shadowed. This would mean that you’re not randomly picking the choice of history. More importantly, it might be that none of the non-paradoxical histories are shadowed, and you’ll have no idea what to look at.
Do random samples until you find enough, then. It wouldn’t be perfect, but it should be close enough that you wouldn’t notice with enough computing power, right?
I can think of ways to simulate those quite easily. It does involve cheating with the environment, but not really cheating with any minds. Mostly the same kinds of tricks mentioned in Eliezers “that’d it take to make me belive 2+2=3” article.
Like, for example, deforming the tiling pattern constantly so that it was always the right type of angles and side lengths where the eyes were looking, and stopping the motion detection from going of on those changes. Or have the stairs tile exactly, just snap people on them up in exact increments of tiles, and again doing clever things with the way motion is detected in the eye.
The pentagons are doable, if you’re willing to cheat, but the spiral staircase is harder; spiral staircases appear to lift things but actually don’t. What would an optical illusion that was true be like? How do you build Penrose steps in 3d?
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.
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.
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.)
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.
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.
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?
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.
Hmm, there are probably other uses for containers with shrunken insides.
Inflatable mattresses (or waterbeds) that can be filled quickly/efficiently.
If rooms can be enchanted in this way (houses can certainly be bigger on the inside) then enchanting a long hallway in this way would allow people to walk longer distances in a short amount of time.
If the container is transparent, it could be used as a magnifying glass for things you placed inside.
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.
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.
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.
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.
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...
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”?
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.
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.
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.
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?
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.
“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.
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.
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.
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.
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.
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.
It’s much harder though, to dodge a bolt that comes straight out of a wall without any warning because you can’t see the person who fired it, who if they have much sense has deliberately moved around so that they’re not only attacking from a point where you can’t see them or fire back, but from an angle where you won’t see the beam either.
All the best ways I can think of to take the magical eye from someone who can do that, and lives in a place without “silly rules” against actually doing it, wouldn’t place me in a position to lose limbs in the encounter. If he’s not as Constantly Vigilant as Moody, he might be poisoned, but assuming it wouldn’t destroy the eye or render it unretrievable, I’d sooner call in an airstrike. Although it’s chronologically too early for transfigured predator drones, which would be my top choice.
Since every time a new magical element like this is posited, the obvious thing to do is ask how someone like Quirrell could abuse it, I’ll note that Canon Voldemort was capable of instantly creating a better-than-new magical prosthetic for Peter Pettigrew after the latter sacrificed his hand for a ritual.
Limb farming his own Death Eaters is thinking too small, particularly since the prosthetics might be identifiable. I’d go with “Imperius innocent civilians into casting the ritual for you and then memory charm them so they don’t notice their limbs have been replaced.” Although maybe you don’t need to replace their arms, since even when they do find out, what are they going to do about it, really?
I know that this is quite old, but it bears mentioning that consent is often a huge issue with magic, for more or less precisely this reason. We also know that it is important in the Potterverse as well, since Pettigrew’s line was:
Flesh of the servant, willingly sacrificed, you will revive your master.
Not to mention:
Blood of the enemy, forcibly taken, you will resurrect your foe.
This shows that consent is important on both ends. Imperius could easily not count as actually giving consent.
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.
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”)
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..)
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.
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.
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).
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.
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.
My guess is that this was a deliberate change. I always thought “cannot be blocked, except by inanimate objects!” was kinda lame.
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.
Maybe it hits a Dementor and that’s how they reproduce.
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?
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.
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.
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.
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.
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!)
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.
That requires original research, like partial transfiguration.
That’s what I had in mind, yes.
Original research is dangerous. This original research in particular seems dangerous.
Now I come to think, he would probably just conclude it uses Earth as a reference frame, just as broomsticks use Aristotelian physics and transfiguration uses form/substance duality.
http://en.wikipedia.org/wiki/The_Billiard_Ball
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.
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?
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.
Of course there’s no proof, but I don’t think it’s really possible, if only for literary reasons, that the Sphere of Stars spell is just a fancy hologram. I think we can take that as fairly strong evidence it’s working as intended.
What is it then? A signal sent from the pioneer horcrux?
So “arbitrary” might be a bit strong, but what’s to prevent him from using the Moon or the Sun as a reference frame? Or even the Earth as a whole, instead of the local part? Even imparting a relative 1000 mph to an object near the equator would be pretty powerful.
“the caster’s rest frame” is relativistically invariant.
But he didn’t say “the caster’s reference frame”, he said “some much larger mass that the wizard thinks is a reference frame”.
Just saying that if the spell is designed to work relative to the rest frame, then no amount of relativistic internalizing will change how it works. Of course it is possible in the HPMOR universe to design new spells, and a competent Wizard with a good grasp of invariance in physics might be able to create a new spell, Attache Momentum.
And I’m just saying, the way Eliezer phrased it above, there’s no singular reference frame—any suitable mass will do.
You are right, he did phrase it this way, which makes this spell unreasonably easy to munchkin. He would have probably thought harder about it were he a DM of an actual DD game.
It seems like a hack of the rules on the level of partial transfiguration. Also, if you house-rule that it requires “magical energy” in proportion to the delta-momentum, it shouldn’t be too overpowered.
Magic works like the author of the story wants it to work.
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.
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.
Didn’t he say that he mentioned the time-turner because it disproves the simulation hypothesis? It would also guarantee that nobody would simulate it.
He seems to have figured out how to simulate it later, but that requires simulating everything, and there’s no guarantee that there will even be a reality with a stable time loop, unless you have the infinite number of realities necessary to allow connectedness, in which case you can’t possibly simulate all the possibilities.
Actually, there is a guarantee that there will be a stable time loop. Look up the Novicov Consistency Principal some time. And I think that was to stop people speculating that magic was being provided by the Matrix Lords, although sadly it doesn’t. I was referring to the corridor tiled with pentagons (although it never actually says they were regular pentagons) and the spiral staircase that lifts you by rotating.
The Novicov Consistency Principal relies on the Kakutani fixed-point theorem, which relies on convexness, which implies connectedness, which implies an infinite number of realities.
It does not.
I admit I’ve never seen a proof of the Novikov Consistency Principle. I know that’s how I’d prove something like that, and I know I could easily come up with a case of time travel with no possible stable time loop of I’m given a discrete space, a non-compact space, etc.
What does it rely on?
Solely on the uniqueness of the metric in GR.
Do you have a link to a better explanation?
Also, can you explain how this could be used to find a stable time loop?
Sorry, I cannot find a link, but feel free to ask what does not make sense. As for the stable time loop, I’m not sure that it is always possible to find, given that you apparently want to fix both initial and final conditions of a hyperbolic PDE, unless I misunderstand what is involved in constructing such a loop.
Couldn’t it be approximated?
The theorem doesn’t tell you how to find a fixed point. It only tells you that one exists.
But if you had done such arduous research as, say, reading the Wikipedia page for the NCP, you would see that a sum over histories using only non-paradoxical timelines apparently works. Not that I really understand that in more than a superficial way, but it sure as hell sounds like an answer to your point.
There are only guaranteed to be non-paradoxical timelines if you have an infinite number of realities, which is what I was saying from the beginning.
You could look for all the timelines that are within delta of being a paradox. I think the shadowing theorem guarantees that, for small enough delta, this is epsilon-close to a non-paradoxical history. I don’t think it tells you what delta is, and I don’t think it’s guaranteed that every non-paradoxical history will be shadowed. This would mean that you’re not randomly picking the choice of history. More importantly, it might be that none of the non-paradoxical histories are shadowed, and you’ll have no idea what to look at.
Do random samples until you find enough, then. It wouldn’t be perfect, but it should be close enough that you wouldn’t notice with enough computing power, right?
I can think of ways to simulate those quite easily. It does involve cheating with the environment, but not really cheating with any minds. Mostly the same kinds of tricks mentioned in Eliezers “that’d it take to make me belive 2+2=3” article.
Like, for example, deforming the tiling pattern constantly so that it was always the right type of angles and side lengths where the eyes were looking, and stopping the motion detection from going of on those changes. Or have the stairs tile exactly, just snap people on them up in exact increments of tiles, and again doing clever things with the way motion is detected in the eye.
The pentagons are doable, if you’re willing to cheat, but the spiral staircase is harder; spiral staircases appear to lift things but actually don’t. What would an optical illusion that was true be like? How do you build Penrose steps in 3d?
Inception sort of almost pulled it of.
Nah, that scene only works from the right angle.
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.
You know that spell was invented for the film, right?
According to the wiki:
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.
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.)
“Making things bigger on the inside” does not equal “bending space into any damn shape we please.”
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.
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.
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.
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.
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?
What happens if you make it bigger on the inside and then turn it inside out?
Could be. Hard to tell without the author telling us.
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.
Oh, I see. Cool. I assumed they were purely theoretical.
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.
Inflatable mattresses (or waterbeds) that can be filled quickly/efficiently.
If rooms can be enchanted in this way (houses can certainly be bigger on the inside) then enchanting a long hallway in this way would allow people to walk longer distances in a short amount of time.
If the container is transparent, it could be used as a magnifying glass for things you placed inside.
Wizards already have shrinking charms for the first one, but well done.
In a sense they are. I’ve never seen anything about anybody actually doing that. I just know it would work in theory.
Lenses and optic fibers and such work on the same principle, but they aren’t cone points.
“When” he dodges it? This seems like strong evidence that Q knew he wouldn’t.
An interesting point. Do we know that he doesn’t, in cases where he wants them dead as an end in itself?
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.
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.
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.
Perhaps it has a range limit.
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.
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.
Hardly obvious to me.
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...
No doubt they feel the same way.
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”?
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.
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.
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.
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?
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
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.
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.
So that’s why Dumbledore set a chicken on fire—he was reviving Fawkes!
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.
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.
For context, the original backstory:
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.
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.
It could be used to force other actions, per Quirrel’s excuse to Harry, and the forced choices lead to limb loss.
It’s much harder though, to dodge a bolt that comes straight out of a wall without any warning because you can’t see the person who fired it, who if they have much sense has deliberately moved around so that they’re not only attacking from a point where you can’t see them or fire back, but from an angle where you won’t see the beam either.
All the best ways I can think of to take the magical eye from someone who can do that, and lives in a place without “silly rules” against actually doing it, wouldn’t place me in a position to lose limbs in the encounter. If he’s not as Constantly Vigilant as Moody, he might be poisoned, but assuming it wouldn’t destroy the eye or render it unretrievable, I’d sooner call in an airstrike. Although it’s chronologically too early for transfigured predator drones, which would be my top choice.
Maybe a dark ritual involving sacrificing a limb to blind someone or something?
Maybe, but I doubt it.
Since every time a new magical element like this is posited, the obvious thing to do is ask how someone like Quirrell could abuse it, I’ll note that Canon Voldemort was capable of instantly creating a better-than-new magical prosthetic for Peter Pettigrew after the latter sacrificed his hand for a ritual.
Limb farming his own Death Eaters is thinking too small, particularly since the prosthetics might be identifiable. I’d go with “Imperius innocent civilians into casting the ritual for you and then memory charm them so they don’t notice their limbs have been replaced.” Although maybe you don’t need to replace their arms, since even when they do find out, what are they going to do about it, really?
I know that this is quite old, but it bears mentioning that consent is often a huge issue with magic, for more or less precisely this reason. We also know that it is important in the Potterverse as well, since Pettigrew’s line was:
Not to mention:
This shows that consent is important on both ends. Imperius could easily not count as actually giving consent.
Moody can still dodge.
That is not obvious at all, at least to me. Or Harry, who seemed to interpret it in terms of risk to bystanders.
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.
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.
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”)
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..)
You do have to aim it by hand and eye. You try hitting a human-sized target from a moving platform at 2km.
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.
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.
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.
Just find something that was made by using up a lot of accuracy. That should do it.
A target with nothing but bulls-eyes will do.
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).
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.
Also, I doubt that everyone else in the room was either clueless or willing to let Harry receive such massively incorrect info.
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.
A killing curse hits a molecule of nitrgen. The molecule bursts. Yep, doesn’t really make sense.