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  Sound of gravity, a middle C, vindicates Albert Einstein

Sound of gravity, a middle C, vindicates Albert Einstein

Published : Feb 12, 2016, 2:19 am IST
Updated : Feb 12, 2016, 2:19 am IST

Scientists said on Thursday they have for the first time detected gravitational waves, ripples in space and time hypothesised byphysicist Albert Einstein a century ago, in a landmark discovery that op

Scientists said on Thursday they have for the first time detected gravitational waves, ripples in space and time hypothesised byphysicist Albert Einstein a century ago, in a landmark discovery that opens a new window for studying the cosmos.

The researchers said they detected gravitational waves coming from two black holes — extraordinarily dense objects whose existence also was foreseen by Einstein — that orbited one another, spiraled inward and smashed. They said the waves were the product of a collision between two black holes 30 times as massive as the Sun, located 1.3 billion light years from Earth.

The scientific milestone, announced at a news conference in Washington, was achieved using a pair of giant laser detectors in the United States, located in Louisiana and Washington, capping a long quest to confirm the existence of these waves.

The announcement was made in Washington by scientists from the California Institute of Technology, the Massachusetts Institute of Technology and the LIGO scientific collaboration.

Like light, gravity travels in waves, but instead of radiation, it is space itself that is rippling.

Detecting the gravitational waves required measuring 2.5-mile (4 km) laser beams to a precision 10,000 times smaller than a proton.

[The New York Times quoted a scientist as saying that the cosmic chirp rose to a middle C note.]

The two laser instruments, which work in unison, are known as the Laser Interferometer Gravitational-Wave Observatory(LIGO). They are able to detect remarkably small vibrations from passing gravitational waves. “We’re actually hearing them go thump in the night,” MITphysicist Matthew Evans said. “We’re getting a signal which arrives at Earth, and we can put it on a speaker, and we can hear these black holes go, ‘Whoop.’ There’s a very visceral connection to this observation.”

The scientists said they first detected the gravitational waves last Sept. 14.

“We are really witnessing the opening of a new tool for doing astronomy,” MIT astrophysicist Nergis Mavalvala said in an interview. “We have turned on a new sense. We have been able to see and now we will be able to hear as well.”

The LIGO work is funded by the National Science Foundation,an independent agency of the U.S. Government.

Einstein in 1916 proposed the existence of gravitational waves as an outgrowth of his ground-breaking general theory of relativity, which depicted gravity as a distortion of space and time triggered by the presence of matter. But until now scientists had found only indirect evidence of their existence.