What makes a warp drive impossible?

[Kojiami]

Why can't you fold spacetime? Everyone says it's impossible, but why? Is it energy required? lack of technology?

[Sisyphus]

I think it's just lack of a theoretical account of how it might actually be accomplished.

[foodchain]

Why can't you fold spacetime? Everyone says it's impossible, but why? Is it energy required? lack of technology?

 

Well, personally from what I know I think the concept of folding spacetime might be a fallacy really, though of course I know so little about what I am talking about. I think its sort of the same as saying at a specific curvature of space knowledge can become matter or something like that, a misinterpretation really.

 

TO fold spacetime, what would that really mean?

[CPL.Luke]

actually you can theoretically create warp drives, its just thatat his time nobody could imagine how to build a device that would accomplish this. For instance the Alcubierre metric shows that it is possible. It is also theoretically possible to fold space time and create worm holes and such, but again nobody knows how to make it happen.

[Sisyphus]

To say that it's "theoretically possible" is sort of misleading, I think. It's not self-contradictory (as far as we know) and we know what the math would look like if it did happen. However, we don't even know if such an event could ever occur, let alone how to actually do it.

[Severian]

There is no physical law that says you can't bend space-time. Indeed, I do it all the time . I have mass (my wife claims too much) so my body warps space-time around it according to Einstein's GR.

 

The reason why this doesn't help with warp drives (a la Star Trek) is that I can't warp them faster than the speed of light. I have to do something to the space in order to warp it and the distance I can reash after deciding to do it is restricted by the speed of light.

[ajb]

22 papers on SPIRES talking about warp drive. I think that is the place to start looking.

 

Generally, space-time engineering requires matter of some sort that is "unphysical". It will have some very odd equation of state or violate some energy conditions or something. trying to come up with "funny" space-times is more a test of our understanding of GR and a way to hint at new physics.