Teleportation physics

[hongi]

If you could teleport Jumper-style, but that still meant you preserve momentum, how would you get rid of that energy?

For example, you grab a baddie and jump several hundred metres into the air. If you teleport several metres below the surface of the ocean, will you still die?

[Grumman]

If you could teleport Jumper-style, but that still meant you preserve momentum, how would you get rid of that energy?

The simplest answer? Gravity. If you're falling at 100 m/s, teleport such that your direction of movement is away from the Earth - either by teleporting to the other side of the planet or with Portal-style manipulation. Then wait until your relative velocity zeroes out (at the peak of your arc) and then teleport to your destination.

[madd0ct0r]

I'd go with Grumman on this one. Force=mass*acceleration. If you slow down really fast (like being underwater) that means a lot of force.

[Grumman]

Actually now that I've thought about it, my suggestion wouldn't work. Due to the rotation of the Earth, the relative velocity of two points on opposite sides of the earth at the equator is 3,400 kph. For obvious reasons, this makes long distance teleportation a bad thing. You can teleport from the North pole to the South pole without too much trouble, but the closer you get to the equator, the nastier it would be.

[madd0ct0r]

Not to mention the velocity involved in going around the SUN as part of Earth's orbit. Presumably you'd want to get that very precisely lined up.

[Grumman]

Not to mention the velocity involved in going around the SUN as part of Earth's orbit. Presumably you'd want to get that very precisely lined up.

No, that part is fine - since the near side of the Earth is going around the sun in the same direction as the far side of the Earth, the relative velocity of that component is pretty much zero.

[madd0ct0r]

yeah, but if you're using a PORTAL type direction trick...

[Grumman]

yeah, but if you're using a PORTAL type direction trick...

No. Unless you're teleporting to Counter-Earth, the Earth's revolution around the sun is not relevant. The Earth is revolving around the Sun at ~110,000 kph, but if you are just looking at that component of the Earth's velocity, it's all moving in the same direction. If your origin point is moving 110,000 kph rimwise, so is your end point, so the relative velocity cancels out.

[madd0ct0r]

Yup, but if you're using a direction portal (ala Portal) you can take that velocity and come out the portal with it facing a different way.
IE, you are on the side of the planet that's currently at the front of the orbit path and you teleport to the same point, but using a portal that brings you out upside down. Suddenly, that velocity is pointing in the opposite direction to the direction the earth's traveling in. splat.

[Grumman]

If you're using portals, it's your velocity relative to the portal on your way in that defines your velocity relative to the other portal on the way out. In other words, if portal 1 is moving 110,000 kph rimwise and you fall into it at 110,100 kph, that's only a relative velocity of 100 kph, not 110,100 kph. Then, if portal 2 is also moving 110,000 kph rimwise but pointing in the opposite direction, you will come out at a relative velocity at 100 kph, or 109,900 kph.

If portals "stick" to objects like portable holes, you're fine.

If linked pairs of portals must move at the same velocity, regardless of the orientation of the portal itself, you're fine.

The only way you're in danger is if portals must inherently be stationary relative to the centre of the universe, or something like that.

~~~

That also made me think of an easy way to use "sticky" portals to negate your velocity relative to the Earth:

1. Take one portal and stick it to the Earth. Doesn't matter where.
2. Take a second portal and stick it to something you're holding, like the side of a briefcase.
3. Just climb through the hole. Since your velocity relative to the briefcase portal is pretty much zero going in, your velocity relative to the earth portal will also be pretty much zero coming out.