Black holes are black because matter and energy can fall in, but nothing can come back out. At the ends of their lives, though, they may evaporate with an outburst of energy. And scientists are looking for such outbursts.
Primordial black holes may have been forged in the Big Bang. They're smaller than an atom, but as massive as a mountain.
Because they're so small, we can't see them directly. But Stephen Hawking predicted that black holes should eventually evaporate. The time it takes depends on the black hole's mass. Some of the tiny ones created in the Big Bang could go off at any time, producing flashes of gamma rays.
Astronomers are looking for these flashes with telescopes carried outside Earth's atmosphere, which blocks gamma rays.
One is the Fermi space telescope. Its instruments should be able to detect an evaporating black hole from its gamma-ray "signature," which is different from other objects. Another is a balloon-based telescope that's flown several times. Scientists hope to have results by the end of the year.
And yet another way to find them might be to put your ear to the ground; more about that tomorrow.
If scientists can't find primordial black holes, perhaps they can make some in a particle accelerator in Europe. The black holes would be so tiny that they'd evaporate as soon as they formed -- providing strong evidence that the Big Bang created a passel of black holes.
Script by Damond Benningfield, Copyright 2009
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