Scientists detect gravity ripples Einstein predicted
WASHINGTON — In an announcement that electrified the world of physics, scientists said Thursday that they have finally detected gravitational waves, the ripples in the fabric of space-time that Einstein predicted a century ago.
Astronomers hailed the finding as an achievement of historic proportions, opening the door to a new way of observing the universe and the violent collisions that are constantly shaping it. For them, it’s like turning a silent movie into a talkie because these waves are the soundtrack of the cosmos in action.
“Until this moment, we had our eyes on the sky and we couldn’t hear the music,” said Columbia University astrophysicist Szabolcs Marka, a mem- ber of the discovery team. “The skies will never be the same.”
An all-star international team of astrophysicists used an exquisitely sensitive, $1.1 billion set of twin instruments known as the Laser Interferometer Gravitational-wave Observatory, or LIGO, to detect a gravitational wave generated by the collision of two black holes 1.3 billion lightyears from Earth.
“Einstein would be beaming,” said National Science Foundation director France Cordova.
The LIGO control room is set up so that data comes in in audio form and scientists can listen by headphones. In this case, the evidence consisted of a single, faint chirp — or perhaps more accurately, a thud — that was picked on Sept. 14.
Some physicists said the finding is as big a deal as the 2012 discovery of the subatomic Higgs boson, known as the “God particle.” Some said this is bigger.
“It’s really comparable only to Galileo taking up the telescope and looking at the planets,” said Penn State physics theorist Abhay Ashtekar, who wasn’t part of the discovery team.
Physicist Stephen Hawking congratulated the LIGO team, telling the BBC: “Gravitational waves provide a completely new way of looking at the universe. The ability to detect them has the potential to revolutionize astronomy.”
Gravitational waves, first postulated by Albert Einstein in 1916 as part of his theory of general relativity, are extraordinarily faint ripples in space-time, the continuum that combines both time and threedimensional space. When massive objects like black holes or neutron stars collide, they send gravitational waves across the universe, stretching space-time or causing it to bunch up.
Scientists found indirect proof of gravitational waves in the 1970s by studying the orbits of two colliding stars, and the work was honored as part of the 1993 Nobel Prize in physics. But now scientists can say they have actually detected a gravitational wave.
“It’s one thing to know soundwaves exist, but it’s another to actually hear Beethoven’s Fifth Symphony,” said Marc Kamionkowski, a physicist at Johns Hopkins University who wasn’t part of the team.
In this case, the crashing of the two black holes stretched and squished Earth so that it was “jiggling like Jell-O,” but in a tiny, almost imperceptible way, said David Reitze, LIGO’s executive director.
The dual LIGO detectors went off just before 5 a.m. in Louisiana and emails started f lying. “I went, ‘Holy moly,’ ” Reitze said.
But the finding had to be tested and verified, using even conventional telescopes, before the scientists could say with confidence that it was a gravitational wave. They concluded there was less than a 1-in-3.5million chance they were wrong, he said.
LIGO technically wasn’t even operating in full mode; it was still in the testing phase when the signal came through, Reitze said.
“We were surprised, BOOM, right out of the box, we get one,” Reitze said.
Reitze said that given how quickly they found their first wave, scientists expect to hear more of them, maybe even a few per month.
It’s really comparable only to Galileo taking up the telescope and looking at the planets.”
Abhay Ashtekar,
Penn State physics theorist