enter image description here

I don't understand how this could work. So lets say the drive is set to go 30,000,000 meters in a straight line to get to a distant planet. Now lets say the ship size is 20 meters. Now let's make the assumption that the warp field in the photo is 30 meters (10 meters bigger than the ship). So the warp bubble is applied. Now the 30 meters of space the ship occupied is cut. But it only could apply the warp bubble to this confined region which means 30 meters are cut instead of 30 million and now 29,999,970 meters are left and the ship is not even close to the planet it wants to go to (barely moves). Are there any solutions to this problem?

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    $\begingroup$ As far as I know the is no proposal for how to accomplish this beyond "get together enough negative energy density material". $\endgroup$ – dmckee Jul 8 '14 at 1:02
  • $\begingroup$ I think that image os of the potential, not of spacetime. The spacecraft has to be moving due to some classical engine. Ideally, one would accelerate to around 0.1c then turn on the drive. The warp bubble contracts all of the space in the pit by some large amount, which means by the time the spacecraft reaches that point in space, there is less proper distance coming out of the pit that it has to travel. Once the spacecraft passes a position, the back of the warp bubble returns it to the correct size. $\endgroup$ – Jim Jul 8 '14 at 13:30
  • $\begingroup$ In this way, the ship travels at 0.1c and crosses the 30 000 000 m in less time than a beam of light because it only sees effectively something like 3 000 m due to the contraction of space in the leading edge of the bubble $\endgroup$ – Jim Jul 8 '14 at 13:31
  • $\begingroup$ I see what your saying. However, most warp drive articles say that the warp bubble warps space-time infront and contracts in the back. So even if the bubble was moving at c it would still take 4 years to warp the distance between it and a star 4 light years away. Am I confused, I think I am mixing something up. $\endgroup$ – user122083 Jul 8 '14 at 20:21

The idea is that the object generating the "pit" in the front is in the center of the flat region in the middle. What happens is that the object in the middle begins to "fall" into the "pit" in front of it, due to gravitational attraction. The "pit", however, moves forward because it is a fixed distance away from the object in the middle. Basically, as the object moves forward, the "pit" moves forward with it.

Imagine a dog with a treat dangling in front of its nose. The treat is hanging from a harness attached to the dog. As the dog moves forward to try to reach the treat, the treat moves forward the same amount, preserving the arrangement of the system, but causing an increase in velocity. The Alcubierre drive works in an analogous manner.

As to how the drive would warp spacetime, I'd consult Wikipedia, which does a much better job explaining this than I could.

  • $\begingroup$ How fast does the pit move though? $\endgroup$ – user122083 Jul 8 '14 at 2:06

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