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Scientists detect ripples in fabric of spacetime a century after Einstein's prediction

Discovery compared to Galileo

National Science Foundation SOURCE: National Science Foundation
Scientists detect ripples in fabric of spacetime a century after Einstein's prediction
Discovery compared to Galileo


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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 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.




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.






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 honored as part of the 1993 Nobel Prize in physics. But now scientists can say they have actually detected a gravitational wave.




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 said.




Detecting gravitational waves is so difficult that when Einstein theorized 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.




Each LIGO has two giant perpendicular arms more than 2 miles long. A laser beam is split and travels both arms, bouncing off mirrors to return to the arms' intersection. Gravitational waves stretch the arms to create an incredibly tiny mismatch - smaller than a subatomic particle - in the beams' signature wave curves. That mismatch is what LIGO detects.

