Fast-spinning black holes might reveal all - physics-math - 08 August 2009 - New Scientist
IT IS the ultimate cosmic villain: space and time come to an abrupt end in its presence and the laws of physics break down. Now it seems a "naked" black hole may yet emerge in our universe, after spinning away its event horizon.
In 1969, physicist Roger Penrose postulated that every singularity, or black hole, must be shrouded by an event horizon from which nothing, including light, can escape. His Cosmic Censorship Conjecture has it that singularities are always hidden.
If the conjecture doesn't hold, it would be bad news for cosmologists. If even one location in the universe cannot be described by the laws of physics, the future of the universe - as predicted by those laws - is cast into doubt. Our description of photons, for instance, may be undermined because those photons may have interacted with a naked singularity while zipping across the universe.
In theory, adding matter to a black hole could make it spin fast enough to shed its event horizon, but previously, physicists have calculated that the spin of black holes has an inherent speed limit that prevents such shedding. This limit is partly determined by the swirling tornado of space-time that surrounds a spinning black hole. Past simulations showed that if material was added that made space-time swirl faster, adding yet more material would be increasingly difficult because the increased centrifugal force might fling it outwards before it could reach the black hole's event horizon, spin it up and disrupt it.
Infalling matter can disrupt a black hole's event horizon, exposing a 'naked' singularity
However, these simulations began by adding matter to a black hole spinning at its maximum possible rate, say Ted Jacobson and Thomas Sotiriou at the University of Maryland at College Park. They simulated adding matter orbiting in the same direction to a black hole spinning just below its maximum rate. Their work suggests that the event horizon could then be disrupted and shed (www.arxiv.org/abs/0907.4146).
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