Black holes and worm holes(smaller black holes) distort space and time greatly. *Black holes are holes in space and time. It is a concentration of matter so dense that the gravitational feild created by it cannot be escaped,not even light. Black holes bend gravity until it rips. Einstein and nathan rosen developed an idea, that a black hole might be connected to another rip in another black hole,joining two disparate parts of space-time by way of a narrow channel. It is believed that black holes are short cuts through space and time
One method of time travel is to put an anti-gravity device within the channel of the wormhole in order to allow a space craft to travel safely through it. The channel linking the two worm holes, is smaller than the center of an atom. So the anti-gravity device enlarges the channel enough to allow access for a spacecraft. Also, anti-gravity keeps the space craft form being torn apart by the black holes' vast gravitational power.
Another method incorporates theory of cosmic strings. J. Richard Gott III suggested that these hypothectical objects might permit travel backwards in time. Cosmic strings are extremely dense, infinitely large, and no wider than a single atom. Theory goes that if two comsimic strings that are parallel, whiz by each other at the speed of light, they would greatly distort space-time. If nearby astronauts exploit this at the right time, then they should be able to end up at their starting point before they even left.
