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Put a Fig Leaf on That Singularity!
10/1/2007
To dumb it down for the non-GR physicists in the audience, a black hole is an object whose properties can be characterized using something along the lines of, oh, say ...
which, obviously, means that you wouldn't be able to detect a black hole if it were staring you in the face, except by indirect evidence, such as your face being removed from your head by the black hole's steep and somewhat unforgiving gravitational gradient ("somewhat" in the sense that some theories would allow for your face to reemerge from the black hole's event boundary as particle-antiparticle radiation, so don't give up hope if that happens to you).
As a consequence, the general idea is that it would be impossible to observe the singularities that constitute a black hole as "naked" phenomena (i.e., directly).
According to a report out of Duke's press office, to undress such a singularity "'would shock the foundation of general relativity,' said Arlie Petters, a Duke professor of mathematics and physics who worked with Marcus Werner, Cambridge graduate student in astrophysics, on a report posted online Monday, Sept. 24, for the research journal Physical Review D." The report said that Petters and Werner have devised a way to test for the presence of black holes--or at least to test whether "cosmic censorship" can ever be violated--by applying the idea of gravitational lensing to spinning singularities.
"In work supported by the National Science Foundation in the United States and the Science and Technology Facilities Council in the United Kingdom, the pair employed a finding that a black hole could be shed of its event horizon and become a naked singularity if its angular momentum--an effect of its spin--is greater than its mass," Duke reported. For a singularity massing about 10 times our own sun, that amounts to "a few thousand rotations a second."
And hence: "In the event that the required conditions were met, Petters' and Werner's calculations show that a naked singularity's massive gravitation would split the light of background stars or galaxies in telltale ways that are potentially detectable by astronomers using existing or soon-to-be instruments."
If the possibility of cosmic nudity makes you uncomfortable, you're not alone.
"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 statement released by Duke. "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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About the author: Dave Nagel is the executive editor for 1105 Media's educational technology online publications and electronic newsletters. He can be reached at dnagel@1105media.com.
Have any additional questions? Want to share your story? Want to pass along a news tip? Contact Dave Nagel, executive editor, at dnagel@1105media.com.
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