(Submitted November 30, 2004)
Can you explain the Kerr Black Hole in detail please? Also, how can it
cause time travel?
Thanks for your question. Kerr black holes were postulated by the
theorist, Roy Kerr in the 1960s. He postulated that a rotating star could
collapse into a black hole with a rotating ring of neutrons at its center
rather than the usual singularity. Kerr believed that since there wasn't a
singularity at the center, one might be able to travel through the black
hole without being crushed by the singularity. Another theoretically
possible scenario is that a person could enter the Kerr black hole and exit
through a white hole on the other side (a white hole would actually push
everything away from it using some form of exotic matter with negative
energy), and, in this way, one could travel through spacetime.
While white holes may be theoretically possible, there is absolutely no
evidence to support their existence. Many theorists do not believe there
is any way to pass through a black hole and that even if it were possible,
one would be torn apart by the enormous tidal forces well before reaching
Hope this helps,
Georgia & Dirk
For "Ask an Astrophysicist"