Scientists
say they heard the faint chirp [listen here] of two black holes colliding a billion
light-years away, fulfilling Einstein’s general theory of relativity.
International New York Times | 11 February 2016
[excerpts]
Conveyed by these gravitational waves, power 50 times greater than the output of all the stars in the universe combined vibrated a pair of L-shaped antennas in Washington State and Louisiana known as LIGO on Sept. 14. ...
LIGO’s antennas are L-shaped, with perpendicular arms 2.5 miles long.
Inside each arm, cocooned in layers of steel and concrete, runs the
world’s largest bottle of nothing, a vacuum chamber a couple of feet
wide containing 2.5 million gallons of empty space. At the end of each
arm are mirrors hanging by glass threads, isolated from the bumps and
shrieks of the environment better than any Rolls-Royce ever conceived.
Thus coddled, the lasers in the present incarnation, known as Advanced
LIGO, can detect changes in the length of one of those arms as small as
one ten-thousandth the diameter of a proton — a subatomic particle too
small to be seen by even the most powerful microscopes — as a
gravitational wave sweeps through. ...
“It was waving hello,” he said. “It was amazing. The signal was so big, I didn’t believe it.”
The frequency of the chirp was too low for neutron stars, the
physicists knew. Detailed analysis of its form told a tale of
Brobdingnagian activities in a far corner of the universe: the last
waltz of a pair of black holes shockingly larger than astrophysicists
had been expecting.
One of them was 36 times as massive as the
sun, the other 29. As they approached the end, at half the speed of
light, they were circling each other 250 times a second.
And then
the ringing stopped as the two holes coalesced into a single black
hole, a trapdoor in space with the equivalent mass of 62 suns. All in a
fifth of a second, Earth time. ...
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