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Third set of gravitational waves detected, Einstein's theory holds

Courtesy Caltech / MIT / LIGO Laboratory

The Laser Interferometer Gravitational-wave Observatory (LIGO) has detected gravitational waves, ripples in space and time, from a third pair of black holes that collided. The merger took place 3 billion light-years away, which is the farthest distance yet, and was observed during LIGO's current run, which started November 30 of last year.

  • The previous two observations occurred in September and December of 2015, and respectively are 1.3 billion and 1.4 billion light-years away.

What we know now:

  • How black holes join in pairs. As black hole pairs spiral around each other they rotate about their own axes, sometimes in the same direction as the orbital motion — but this is the first time at least one of the black holes may not have been aligned with that motion. That implies this black hole pairing could have formed later in their lives. The other theory purports that black holes join in pairs as they are born together, which happens when each star in a pair explodes, thus leaving the black holes spinning in alignment since the original star pair spun in alignment.
  • The scientists tested Albert Einstein's general theory of relativity, and it held. The theory says that as black holes orbit around each other they lose energy through gravitational waves, or more simply, that massive objects cause distortions in space-time, which results in what we experience as gravity.

What's next: The project will likely expand its network of detectors by this summer to better pinpoint the signals, according to a spokesperson from Virgo, one of the collaborators on the program. The LIGO's next run is in 2018 and National Science Foundation director France Córdova predicts the LIGO will one day deliver observations daily.