Is momentum conserved when teleporting?

[ceswiedler]

Those consequences only exist if the rules of that world acknowledge Einstein. Newton, on the other hand, has much fewer complications.

Both of the examples (teleporting into lakes, and teleporting small rocks) rely only on Newton's laws conservation of momentum. The difference in velocity is due to the rotation of the earth (things closer to the equator are moving faster than things near the poles), not anything relativistic.

Of course, there's no reason why the rules of that world should acknowledge Newton, either... Furthermore there's no reason why D&D worlds have to be rotating spheres, or spheres at all. (Does any of the official cosmology describe the material planes that way?)

 

[Tale]

The difference in velocity is due to the rotation of the earth (things closer to the equator are moving faster than things near the poles), not anything relativistic.

That is relativistic. The basic premise of relativity is that there are no privaledged frames of reference. Ignoring that, the rotation of the earth is irrelevant because you can accept that the ground is a privaledged frame and all measurements are related to that.

 

[ceswiedler]

That is relativistic. The basic premise of relativity is that there are no privaledged frames of reference. Ignoring that, the rotation of the earth is irrelevant because you can accept that the ground is a privaledged frame and all measurements are related to that.

What I meant is that you can derive the result by using (only) Newton's laws, as long as you know you're on a rotating sphere and not a flat plane. Contrast with the behavior of objects traveling close to the speed of light, where Newton's laws won't give you the correct result.

Also I don't think that a rotating sphere can be considered a (relativistic) privileged frame of reference, since its rotation is a form of acceleration.

 

[malraux]

That is relativistic. The basic premise of relativity is that there are no privaledged frames of reference. Ignoring that, the rotation of the earth is irrelevant because you can accept that the ground is a privaledged frame and all measurements are related to that.

Rotating screws with stuff. But moreover, you can't just go relative to the ground, because your speed changes drastically depending on your latitude. Someone on the equator is going at ~1000mph (1760 squares per round) relative to the ground at the pole.

 

[Tale]

What I meant is that you can derive the result by using (only) Newton's laws, as long as you know you're on a rotating sphere and not a flat plane. Contrast with the behavior of objects traveling close to the speed of light, where Newton's laws won't give you the correct result.

Also I don't think that a rotating sphere can be considered a (relativistic) privileged frame of reference, since its rotation is a form of acceleration.

Sure it can. Look at the ground. Do you look like you're moving compared to it?

Then giving that priveledge, you're really not moving.

 

[WalterKovacs]

One point about the "don't let eladrin get out of falling to their death by teleportation" thing:

Unless the party is made up entirely of eladrin, or some combination of eladrin and other teleporting characters ... you can't save the whole party that way. If one member of the party gets to the bottom of a 1000 foot cliff, or whatever distance they have to fall ... the rest of the party have to get down there too. Not to mention there are quite a few magic items and spells that also involve avoiding fall damage, etc.

EDIT:

Tale - IF you are in a car going around a corner, look at your feet. Are you moving compared to the car? No. The car is a frame of reference, but unless it is going straight at a constant speed, it is accelerating (deceleration is negative acceleration, and turning is accelerating in a different direction, even if your speed is constant) and therefore not a relativistic priviledged frame of reference.

Because of the size of the earth, and the speed it is rotating/going around the sun ... it is much closer to approximating a frame of reference with constant velocity, so it's not as big of an issue to assume that it is one.

However, he D&D "world" may not actually be planets, but instead a sort of "Flat Earth" that operates on slightly different rules, considering the cosmology of planes, etc.

 

[ceswiedler]

Sure it can. Look at the ground. Do you look like you're moving compared to it?

Then giving that priveledge, you're really not moving.

You can perform tests which indicate that you are under rotational acceleration, for example observing the Coriolis effect. "The ground looks like it isn't moving" isn't much of a scientific test; the ground also looks like it's a flat plane.

 

[Charwoman Gene]

Speedy thing goes in, speedy thing comes out.

 

[Tale]

You can perform tests which indicate that you are under rotational acceleration, for example observing the Coriolis effect. "The ground looks like it isn't moving" isn't much of a scientific test; the ground also looks like it's a flat plane.

I'm not seeing the argument. This isn't a scientific test. We're not talking truly about science. We're talking about disregarding particular aspects of science for simplicity and magic.

We can consider the earth a priveledged frame for the purpose of using magic (teleportation, immoveable rods) while still acknowledging momentum. One doesn't discount lead to the other.

 

[Alex319]

Those consequences only exist if the rules of that world acknowledge Einstein. Newton, on the other hand, has much fewer complications.

What do you mean? The Coriolis effect (which is also caused by differing planetary rotation speeds at different latitudes) was known long before Einstein, and has nothing to do with relativity theory.