In a fic I'm writing, twice I have people falling through the air and Apparating. The question I've been wrestling with, is what happens to the momentum?

I've came up with three answers, but I'm not sure which one I agree with, if any of them. So:

1. Momentum is carried through to the other side. Apparition is a magical element and thus, outside of physical laws, so whatever is happening is suspended while traveling by Apparition and picks up on the other side.

2. Momentum is carried into Apparition, making the journey a little faster, but since it's controlled mainly by magic, any and all momentum is lost by the time they arrive at their destination.

3. The act of Apparition strips any momentum from the person. Almost like a Petrifying Charm, it stops momentum in place.

4. ???

Any thoughts on this would be appreciated.

 

Magic happens during Apparition.

You can regard or disregard any physical forces as much as you see fit, as long as you use them consistently and try writing it to sound plausible.

 

Don't you have to spin around in place to Apparate? I don't know if you can do that while falling.

Well if I'm wrong (a canon nerd can point that out), I guess it depends. The first option might be good if you want to increase dramatic tension. They couldn't just Apparate in mid-air at terminal velocity without being hurt somehow or even possibly dying on the other side (like getting flung into a wall or into the ground or whatever and breaking your skull open), so they'd have to find another way to save themselves.

I don't know if the second option makes sense. Apparition is supposed to be practically instantaneous, so making it even faster is a bit odd. However, maybe it could increase the chances of splinching?

The third option should be pursued if you don't want to bother with the implications of the first option, and you want a consequence-free way out of danger so you can get on with things.

I can't say whether I prefer any one over the other. Just go with whichever works best for the story.

 

Travel magic seems to include a sense of time and distance being crossed. Apparition twists a person through a metaphorical hosepipe, Portkeys yank from the center of gravity and the Floo sends one spinning. I'd take it from this that the magic nullifies (or at least minimizes) any previous inertia.

This might explain why Hagrid was so skeptical about James and Lily dying in a car crash (aside from the fact that he knew they didn't)- if either one knew a crash was happening, they could apparate to the side of the road before impact, none the worse for wear.

My leftover question about this is 'how do they safely transport people with injuries?' Logic would suggest that a Full Body-Bind was a necessary preparation before transporting the wounded, but you never see it done.

Nauro's right though- there is no canon guidance here, so you can play it however works best for your story, so long as it's consistent.

 

Well, if it didn't conserve momentum the planet's movement would probably fuck you over somewhat. But then again... magic.

So I reckon that if you can make it work, make it work. The question would be whether a person could be composed enough to focus on Apparition whilst falling to their death.

 

I prefer to think of it as that candy bar atomizing scene from Willy Wonka.

And yes, I'm being sarcastic.

Or am I?

 

With you, Anarchy, we can never tell.

 

There's been at least one canon instance of people Apparating in mid-air (the trio, fleeing the Lovegood house in DH), but I can't recall what happens when they reappear off hand. Given that they were falling through a partially collapsing building and partly concealed under the Cloak, I can't see them spinning.

 

For some reason, that just gave me the mental image of a wizard riding a bomb down from a plane, screaming, "YAHOOOO!" with a cowboy hat.

...

And then apparating away a second before it hits the ground.

 

Apparation was taught with the three Ds: Destination, determination and deliberation. In HBP they were told to move with deliberation, and turning on the spot was just the most common way of doing so. So no, you don't need to turn on the spot to apparate, most people do however because that's how they first learn.



On topic, what everyone else says. Pick whichever option best fits your story.

 

Harry and Hermione jump out of Bathilda's second story window and apparate away in midair. Unfortunately, Voldemort's memory of the Potters' deaths cuts in an we don't get to see them land.

Yet another reason to dislike that flashback.

 

I developed something called the Principle of Normal Speed for Alexandra Potter. It's mainly a part of Transfiguration, but it could transfer over to apparition too.

The idea is this: when you Transfigure an object, the speed of the consequent object is decided by the idea of normal speed. So let's say someone shoots a bullet at me and I Transfigure it into a tennis ball. The tennis ball isn't travelling towards me at the speed of a bullet. No - it travels towards me at the normal speed of a tennis ball.

This is then extended by the Principle of Deviation. This states that if the antecedant object deviates from its normal speed, then the consequent object will deviate for its normal speed too - by the same degree and in the same direction. So if someone throws a tennis ball at me really hard and I transfigure it into a bullet, it will be a very fast bullet.

Of course this then leads to the (philosophical) question of what normal speed is. It's not subjective - it doesn't depend on the ideas of the caster. I couldn't change the normal speed of an object for my spells by confunding myself. At the same time, it's not objective - it's not some natural constant (an absurd idea anyway, especially as many of these objects are man-made), nor is it the average speed of all the tokens of that object type in the world.

So it's something in between objective and subjective. What wizards call interjective facts.

ANYWAY, it's kinda obvious how this would answer your question. If I apparate from falling to walking, then my walking speed depends on my falling speed. If I was falling at normal falling speed, then I appear walking at normal walking speed. If my falling speed deviates from the norm, however, then my walking speed when I appear will deviate by the same degree.

 

As a side question to what happens to momentum when apparating, what about what happens to your state of position when apparating? If you are falling towards the ground upside down and you apparate, do you arrive at your destination on top of your head or do you arrive standing up? If you apparate while laying down, do you arrive at your destination laying down or do you arrive standing up? This is just a little extension that the original question got me curious about.

 

My version of the "it's magic" explanation: momentum is not a problem, because of the "Destination" component of the whole process. As Twycross said, "You must concentrate continually upon your destination."

If you are doing this correctly, you are naturally compensating for any difference in local velocity and acceleration, focusing upon the destination as being a stationary target to apparate to. The wizard's magic does the rest. In this way, I hypothesize that it would be perfectly reasonable for a wizard on the ground to Apparate into a moving airplane, if he's focusing on the destination properly.

Same deal. Since you're probably focusing upon the destination as being stationary and "properly orientated," that is how you end up after you apparate.

 

The only reason I thought someone might arrive laying down (on top of their head) if they apparated laying down (falling upside down) is because that is how I believe it works with portkeys. In the Goblet of fire, when Harry portkeys back to Hogwarts after Voldemort's rebirth, he arrives laying on the ground holding Cedric in the same position as when he portkeyed from the graveyard. I know apparation and portkeying are not the same, but they are both a form of magical trasportation and may share similar mechanics.

 

Portkeys are tricky to compare to other things, because when you think of it, there's multiple interesting characteristics to Portkey travel.

Consider the Quidditch World Cup Portkey. We know that the part of your body touching the Portkey remains rigidly attached to it. And at the same time, it feels to Harry like there's a "hook behind his navel." But the rest of your body isn't so rigid - Harry describes himself banging into the shoulders of people next to him. So that's at least two different attach points - the object, and the hook, the latter of which possibly explaining why the travelers don't have an impression of dangling from that single finger.

Hmm. If I were writing a fic that mentioned the history of Portkeys, I think I'd have it be a trial-and-error process. Maybe the first attempt of the Portkey spell didn't have the supporting "hook," resulting in the wizard having his finger or hand ripped off, and the rest of his body remaining where it started.

 

Best answer. Lets go with this one.

 

I'm stuck between Taure's answer, and Blazzano's answer. Either way, it makes sense.

Taure, if I decide to use your methodology, I'll footnote it (and give a link for your story if you'd like). Since you developed it for a story, I'd consider it too much like plagiarism if I didn't give credit.