Time Travel
Moving
Backward In Time: Kerr Black Holes and Worm Holes
A black hole occurs when a sufficiently large mass is compressed into a sufficiently small space. The gravitational field of a black hole is so massive that it warps both space and time. Any objects in its vicinity will be pulled inside and crushed. While such a black hole would be deadly, a second type of black hole called a Kerr black hole could potentially offer a mode of space/time travel. Because of a Kerr black hole's centripetal motion, a singularity would not be capable of forming. As a result, the contents of the black hole would have to be expelled in some way. Physicists hypothesize that there may be an opposite of black holes, known as "white holes." Rather than pulling matter and light into themselves, white holes would eject light and matter (1).
A black hole occurs when a sufficiently large mass is compressed into a sufficiently small space. The gravitational field of a black hole is so massive that it warps both space and time. Any objects in its vicinity will be pulled inside and crushed. While such a black hole would be deadly, a second type of black hole called a Kerr black hole could potentially offer a mode of space/time travel. Because of a Kerr black hole's centripetal motion, a singularity would not be capable of forming. As a result, the contents of the black hole would have to be expelled in some way. Physicists hypothesize that there may be an opposite of black holes, known as "white holes." Rather than pulling matter and light into themselves, white holes would eject light and matter (1).
 http://www.sipl.technion.ac.il/~avi/horizon/Horizon_heb_files/image001.jpg |
A black and white hole pair could exist at distant regions of both space and time, allowing for travel between the two. Not only would the traveler be able to traverse vast regions of space, they could hypothetically travel to a previous point in time as well. For example, the Doctor could enter a Kerr black hole in the TARDIS near present day earth and emerge in a galaxy far away and some time ago. The problem with such a mode of time travel is that it is non-reversible. Because the traveler emerges through a white hole, it would be impossible for them to force their way in the opposite direction to emerge at their starting point. As a result, the individual would be stranded a long way from home with no way of returning. This is where methods of travel such as worm holes become more attractive options. Einstein-Rosen bridges (worm holes), unlike Kerr black holes, are not unidirectional. Rather, they can be thought of more a corridors between two points in space-time. Worm holes could arise from the distortion of space-time by sufficiently large masses, as allowed by Einstein's theory of general relativity (1). Such a passageway would be far more convenient for time traveling, as one would be able to not only visit a distant place or era, they would be able to return and share their experience. |