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Listening for gravitational waves from the birth of the universe

作者:楚泞    发布时间:2019-02-27 03:03:07    

AEI/MM/Exozet/NASA/Henze By Richard Webb When the champagne has been on ice for nigh on a century, the corks pop all the louder. So it was last month, when physicists announced the first direct detection of a gravitational wave. That’s just the beginning of the story, however. The existence of gravitational waves was one of the first predictions to emerge from Einstein’s theory of gravity, the general theory of relativity, a century ago – and it was one of the last to be verified. General relativity tells us that gravity results when massive bodies like Earth, the sun and black holes distort space and time around them. When such bodies move and accelerate in each other’s gravitational fields, the result should be a series of tiny distortions, wave-like ripples in the fabric of the universe that radiate out. For the past 40 years we’ve had indirect evidence of gravitational waves from a pair of neutron stars engaged in a death dance. Since the snappily titled PSR B1913+16 binary was sighted in 1974, the distance between the two stars has been slowly contracting, exactly as general relativity predicts if they were losing energy by radiating gravitational waves. Those waves have never been directly detected, perhaps because they are just too slight. But on 15 September last year, Advanced LIGO, a vast facility spread over two sites in Louisiana and Washington state,

 

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