Trio of detectors homes in on black hole sources of gravitational waves

For a fourth time, physicists have spotted

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gravitational waves—ripples in space itself—set off by the merger of two massive black holes. But this time, they detected the waves not only with two detectors in the United States, but also with a third detector in Europe: the Virgo detector near Pisa, Italy. The three-way detection enabled researchers to home in on the location of the black holes on the sky with 10 times greater precision than before, and to probe the polarization of gravitational waves in new ways. The result also independently confirms the blockbuster discovery of gravitational waves made 2 years ago.

"Virgo is in the game and that's very important," says Clifford Will, a gravitational theorist at the University of Florida in Gainesville who was not involved in the work.

Gravitational waves are a spectacular prediction of Albert Einstein's theory of gravity, general relativity. Einstein explained that gravity arises because massive objects warp space and time. When these objects spin around each other like twirling barbells, he predicted, they should produce ripples in spacetime, or gravitational waves, that spread at light-speed.

http://www.sciencemag.org/news/2017/09/trio-detectors-homes-black-hole-sources-gravitational-waves