Originally posted on sciy.org by Ron Anastasia on Wed 26 Sep 2007 01:00 AM PDT
Black holes are weird enough. Breaking down known laws of physics to
the point of unimaginable conditions qualifies as genuinely strange.
But a team of Duke University and Cambridge researchers has now outlined a new twist on the theory, in which a fast-spanning black hole might shed some of the natural shields that keep scientists from observing it directly, becoming what they call a “naked†singularity.
The traditional model of black holes posits an object, such as a collapsed star, for which gravity is so strong that not even light can escape. The radius at which this effect begins – the point beyond which the mass of the object twists space so completely that ordinary laws of physics break down – is called the event horizon.
However, in a paper published this week, Duke professor Arlie Petters, working with Cambridge graduate student Marcus Werner, argue that a particular kind of black hole may not be entirely black after all, if certain conditions are met.
Petters studies gravitational lensing, or the ability of massive objects to curve space so that it can split light from distant objects into multiple images. He's previously shown that a non-spinning singularity might have this effect, allowing them to be studied more directly.
However, non-spinning black holes don't seem to exist in nature. So he and Werner applied the analysis to singularities that might actually exist. They calculated that under some conditions – those in which the angular momentum of the object exceeded its mass – the effect could work.
That would translate into rotations of a few thousand times per second for an object weighing 10 times more than the Sun, the researchers say.
Could such a thing actually exist, allowing scientists to probe the internal secrets of a black hole with instruments that exist now or in the near future? Possibly, but it's far from certain, the researchers say.
"If you ask me whether I believe that naked singularities exist, I will tell you that I'm sitting on the fence," said Petters. "In a sense, I hope they are not there. I would prefer to have covered-up black holes. But I'm still open-minded enough to entertain the 'otherwise' possibility."
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