WASHINGTON—In an announcement that electrified the world of astronomy, scientists said yesterday they’ve 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—one that opens the door to a new way of observing the universe and the violent collisions that constantly are 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 member of the discovery team.
“The skies will never be the same.”
An all-star international team of astrophysicists used an excruciatingly 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 light-years from Earth.
“Einstein would be beaming,” said National Science Foundation director France Cordova.
To make the finding easier to comprehend, the scientists converted the wave into sound.
At a news conference, they played a recording of a single chirp—the signal they picked up on Sept. 14.
It was barely perceptible even when enhanced.
“That’s the chirp we’ve been looking for,” said Louisiana State University physicist Gabriela Gonzalez, scientific spokeswoman for the LIGO team.
Scientists said they hope to have a greatest hits compilation of the universe in a decade or so.
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.
“Our understanding of the heavens changed dramatically.”
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 three-dimensional 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 like a fishing net.
Scientists found indirect proof of gravitational waves in the 1970s by studying the orbits of two colliding stars, and the work was honoured as part of the 1993 Nobel Prize in physics.
But now scientists can say they’ve 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 Kamionkowsi, a physicist at Johns Hopkins University who wasn’t part of the discovery team.
“In this case, we’re actually getting to hear black holes merging.”
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 e-mails started flying.
“I went, ‘Holy moly,’” Reitze recalled.
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-3.5-million chance they were wrong, he noted.
Detecting gravitational waves is so difficult that when Einstein first theorized about them, he figured scientists would never be able to hear them.
In fact, the greatest scientific mind of the 20th century came to doubt himself in the 1930s and questioned whether such waves really do exist.