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| The gravitational-wave “chirp” observed by Advanced LIGO’s Hanford and Livingston detectors of the chirp from two black holes of 29 and 36 solar masses, respectively, merging 1.3 billion light-years away. Image: LIGO |
iON creates and explains the chirp in the 2016 13 February Payday.
A team of scientists announced that they had heard and recorded the sound of two black holes colliding a billion light-years away, a fleeting chirp (which rose to the note of middle C before abruptly stopping) that fulfilled the last prediction of Einstein’s general theory of relativity.
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 14 September 2015.
When black holes spiral toward each other and merge, they emit a “chirp”: space-time ripples that grow higher in pitch and amplitude before abruptly ending. The chirps that LIGO can detect happen to fall in the audible range, although they are far too quiet to be heard by the unaided ear. You can re-create the sound by running your finger along a piano’s keys. “Start from the lowest note on the piano and go to middle C,” said Rainer Weiss of the Massachusetts Institute of Technology. “That’s what we hear.”
