Gravitational Waves Detected After a Century of Searching

Gravitational Waves, Smithsonian

A supercomputer simulation shows the gravitational waves produced as two black holes merge. (Henze, NASA)
Two merging black holes sent out a signal 1.3 billion years ago that now confirms a key prediction of Einstein’s relativity.  As two black holes spiraled toward each other and merged, they created ripples in the fabric of the cosmos in exactly the form physicists have predicted for a century: gravitational waves. Unveiled today during a suite of international press conferences, the signal paves the way for a whole new understanding of the universe.

“This is the first time the universe has spoken to us through gravitational waves. Up until now we have been deaf,” LIGO Laboratory Director David Reitze, of the University of Florida, said today at a press event in Washington, D.C.

At the root of gravitational waves is Albert Einstein’s theory of gravity, which says that anything with mass warps the very fabric of space-time. When massive objects move, they create distortions in the cosmic fabric, generating gravitational waves. These waves ripple through the universe like sound waves pulsing through the air.

Einstein’s theory predicts that the universe is teeming with gravitational waves, but until now we hadn’t been able to detect them, in part because the waves are exceptionally faint. But even before its upgraded instruments came officially online last year, the Laser Interferometer Gravitational-Wave Observatory (LIGO) picked up a clear signal from the powerful collision of two black holes 1.3 billion light-years away.

“To have a gravitational wave signal detected while LIGO is still not near design sensitivity in the first science run is astonishing, it’s jaw-dropping, in a good way” says Joan Centrella, who headed up the Gravitational Astrophysics Laboratory at NASA’s Goddard Space Flight Center before becoming the deputy director of the Astrophysics Science Division at Goddard.

That exhilaration rippled through LIGO’s Livingston, Louisiana, observatory and through the rest of the world as the team made their announcement. Nearly everything that astronomers have learned about the cosmos has come from different forms of light, such as visible, radio waves and X-rays. But just as seismic waves can reveal hidden structures deep inside Earth, gravitational waves carry with them information about hidden properties of the universe that even light can’t reveal.

“We began with a high-risk job with a very high potential payoff,” Kip Thorne, a LIGO co-founder and a gravitational physicist at the California Institute of Technology, said during the press event. “And we are here today with a great triumph—a whole new way to observe the universe.” …  read more, see video —>


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