Third gravitational wave detected

SPIE Classics offers a look at the timeline of LIGO's historic discoveries of gravitational waves.

01 June 2017

The Laser Interferometer Gravitational Wave Observatory (LIGO) announced 1 June 2017 that a gravitational wave had been detected 4 January -- the third time in under two years. 

Gravitational waves are ripples in the fabric of space time arriving at Earth from a cataclysmic event in the distant universe. LIGO made headlines when they announced the first observation of a gravitational wave in September 2015. This confirmed a major prediction of Albert Einstein's 1915 general theory of relativity and opened an unprecedented new window to the cosmos.

LIGO detected a second gravitational wave in December, 2016.

"This signal was detected on the evening of Christmas Day in the Pacific Northwest," said Fred Raab, Head of LIGO Hanford Observatory, "but received the scientific designation GW151226, based on the UTC date and time used for astronomy."

Detecting three waves in less than two years leads astrophysicists to theorize that mergers between black holes in this mass range are so common that when LIGO is operating at full sensitivity, they may detect as many as one a day.

According to LIGO scientist Szabolcs Marka, everything in astronomy is like the eye. For centuries, telescopes have given stargazers increasing access to the electromagnetic spectrum, expanding the ability to see deeper into time and space.

Astronomy has finally "grown ears," Marka said. "We never had ears before."

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