Black Hole Time Travel By Stephen Hawking
A theoretical explanation of how extreme gravity in a black hole can be used for time travel. However the consensus among scientists of late is that black holes are so destructive, spaceships would be torn to subatomic bits if they tried such a thing. But then again latest research raises the possibility that back holes may not annihilate everything and the potential for hypersapce and time travel is still open.
Time travel has been a common plot in science fiction films and novels since the late 19th century, and the theories of special and general relativity allow methods for forms of one-way travel into the future via time dilation, however at present it is not known whether the laws of physics would allow time travel into the past.