Science Forums 2

[anonymous]

assuming you're serious...

General relativity permits time travel in the forward direction only. The spatial direction of the traveller is irrelevant, but as the velocity of the traveller approaches c, time slows relative to the 'stationary' reference frame. This means that one way time machines already exist; any astronaut that has flown on a high speed space craft has travelled into the future, albiet by a small fraction of a second.

Of course, there are exceptions to every rule. Kip thorne has popularized an application of General relativity which through the use of a wormhole where one end is stationary and the other in motion, creates a tunnel to the past. I personally disagree with Thorne, primarily because he ignores the necessity of matter moving THROUGH dimensional space to create time dilating effects. His model moves space through space, which should create no net dilation.

In terms of reverse time travel, I think this would much more likely be accomplished by creating a specialized gravitational field that reverses time flow with intensity. Also, there is some promising research in optics that utilize q. mechanics for reverse time travel.