# Space-Time Distortion and Warp-Drive

• srs101

#### srs101

I have heard many claims about the effects of space-time distortion but not really anything specific as far as matter.

For example: I place two spheres 5 meters apart on the z-axis into empty space-time that is not at all distorted. Then I proceed to evenly stretch all of the space-time in that area by a factor of two along the z-axis. Is the result still two spheres that are 5 meters apart or two ellipsoids that are 10 meters apart?

I ask this to help me understand how warp-drive could possibly function, and what effects it would have on the space that was warped.

I hope this isn't a stupid question.

I place two spheres 5 meters apart on the z-axis into empty space-time that is not at all distorted.

Strictly speaking, you can't do this. The spheres themselves distort spacetime, since they contain some amount of matter and energy. And matter and energy can't just appear from nowhere.

But you could just start with the spheres 5 meters apart and static. Note that, because the spheres would attract each other, you need to also put something in between them to hold them apart.

Then I proceed to evenly stretch all of the space-time in that area by a factor of two along the z-axis.

How would you do this? Spacetime doesn't "stretch" on its own. Note that all of the proposals (which are all highly speculative and probably aren't physically possible) require some kind of "exotic matter" (which nobody knows how to make and which probably isn't physically possible). And the effect of this, even if it were possible, wouldn't be to "evenly stretch spacetime"; it's more complicated than that.

Is the result still two spheres that are 5 meters apart or two ellipsoids that are 10 meters apart?

First, not that it isn't space that stretches; it's spacetime. In relativity, you can't just distort space or time separately; you have to distort both, because they are not separate things.

For a typical speculative "warp drive", the distortion doesn't affect objects inside the "warp bubble"; it only affects the boundary of the "bubble"--in fact the distortion is the boundary of the bubble. The typical effect is to, heuristically speaking, shorten spacetime in front of the bubble and lengthen it behind the bubble, so that the bubble appears to move faster than light. (Again, bear in mind this is highly speculative and probably not physically possible.) So the spheres themselves wouldn't change; only the boundary of the bubble would.

srs101
I am aware that most of the things required for this scenario aren't possible, but all of that aside, would space-time distortion ever effect the dimensions of a object?

I am aware that most of the things required for this scenario aren't possible, but all of that aside, would space-time distortion ever effect the dimensions of a object?

Tidal forces, caused by differences in spacetime curvature, cause stresses in objects, but I'm not sure what happens when the curvature is relatively even.

srs101
would space-time distortion ever effect the dimensions of a object?

In general, the answer is yes, it's possible. See below.

Tidal forces, caused by differences in spacetime curvature

Tidal gravity is not caused by differences in spacetime curvature; tidal gravity is spacetime curvature. If tidal gravity is strong enough, it can indeed distort objects.

srs101
Thank you.

If a warp drive is made some day (despite it's mostly impossible) , can it be used to travel anywhere? like in the atmospheres of the planets...
and also do the environmental conditions affect the ship, when it's traveling at a very high speed, like the air resistance, resistance by the particles in the space?

It seems a warp [ala alqubierre] drive would really mess up matter on the leading 'edge' of its warp bubble. Assuming I understand the basic idea, I foresee it would cause the distance between nucleons to shrink - which sounds like the recipe for a disaster of epic proportions.

It seems a warp [ala alqubierre] drive would really mess up matter on the leading 'edge' of its warp bubble. Assuming I understand the basic idea, I foresee it would cause the distance between nucleons to shrink - which sounds like the recipe for a disaster of epic proportions.
Which means, the shape of the ship affect the speed when it travels in atmospheres? ( like an air craft?) Or , only the warp bubble faces all the matter?
Well I really like to know whether a warp ship can be used to travel anywhere? Even in water?...
Because, if the space time distortion happen in the edge of the bubble, I think the ship has the capability to travel in slightly denser medias than the space... as even in the space there are particles.
I don't know my question is really clear ... and sorry if it isn't!