Because black holes are impossible to see, one of scientists’ best hopes to study them is to look for the ripples in space-time, called gravitational waves, that they are thought to create.

Gravitational waves¬†would be distortions propagating through space and time caused by violent events such as the collision of two¬†black holes. They were first predicted by Einstein’s general theory of relativity; however, scientists have yet to find one.

That could change when the latest version of a gravitational wave-hunting facility gets up and running. The Laser Interferometer Gravitational Wave Observatory (LIGO) is actually a pair of observatories, in Louisiana and Washington state, that began operating in 2002. Newly sensitized detectors are being added to both.

“The advanced LIGO detectors that are now being installed will see out through a substantial part of the universe,” said California Institute of Technology emeritus professor of physics Kip Thorne, a leading proponent of LIGO. “We expect to see black holes colliding at a rate of perhaps somewhere between once an hour and once a year.”

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