Kerr black hole
Kerr black holes are probably the commonest in nature, since the massive stars from which they typically form possess rotation (but no overall charge) before they collapse at the end of their lives. By the principle of conservation of angular momentum, much of this spin is then retained by the black hole following the star's terminal collapse.
A Kerr black hole has the following distinct regions:
Inside a Kerr black hole
The Penrose diagram to the right, which shows the internal structure of a Kerr black hole, makes this clear. The dark blue path is of an traveler coming from the past in universe #1, crossing the outer horizon then the inner one, avoiding the singularity, crossing the horizons again, and finally emerging in another universe. The light blue path is of a traveler who crosses the singularity and thereby arrives in a "negative universe".
Warning to travelers!Everything that has been said here is purely theoretical. The Kerr solution is very unstable, corresponding as it does to a black hole in complete isolation. The addition of extraneous matter, such as even the approach of a would-be traveler, could be enough to destabilize the Kerr solution and make travel through the black hole unrealistic. To properly investigate the feasibility of journeys past or through the singularities of black holes we need to be able to take quantum effects into account. However, this will require a quantum theory of gravity – one of the chief goals of contemporary theoretical physics.
Compare with Schwarzschild black hole and Reissner-Nordstrom black hole.
Related categories• BLACK HOLES
• SPACE AND TIME
• GRAVITATIONAL PHYSICS
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