What is GW150914?
[[File:LIGO measurement of gravitational waves.svg|thumb|254x254px|[[LIGO]] measurement of the gravitational waves.]] GW150914 was the first direct observation of [[Gravitational wave|gravitational waves]] and was made on September 14 2015 and announced on February 11 2016.<ref>{{Cite journal|last=Castelvecchi|first=Davide|last2=Witze|first2=Alexandra|date=2016-02-11|title=Einstein's gravitational waves found at last|url=https://www.nature.com/articles/nature.2016.19361|journal=Nature|language=en|doi=10.1038/nature.2016.19361|issn=1476-4687}}</ref> The waves were caused by the [[Binary black hole|merger]] of two [[Black hole|black holes]]. The [[waveform]] detected by both of the LIGO observatories matched the predictions of [[general relativity]]. The black holes measured around 36 and 29 [[Solar mass|solar masses]]. Efforts to prove that gravitational waves even existed had been ongoing for over fifty years to the point that [[Albert Einstein]] himself didn't think they would ever be detected.<ref>{{Cite web|title=The long road towards evidence|url=https://www.mpg.de/9966773/background|access-date=2024-04-03|website=www.mpg.de|language=en}}</ref> The event confirmed the last remaining directly undetected prediction of general relativity and especially in the context of large scale events.<ref>{{Cite journal|last=Abbott|first=B. P.|last2=Abbott|first2=R.|last3=Abbott|first3=T. D.|last4=Abernathy|first4=M. R.|last5=Acernese|first5=F.|last6=Ackley|first6=K.|last7=Adams|first7=C.|last8=Adams|first8=T.|last9=Addesso|first9=P.|last10=Adhikari|first10=R. X.|last11=Adya|first11=V. B.|date=2016-05-31|title=Tests of general relativity with GW150914|url=https://doi.org/10.1103/PhysRevLett.116.221101|journal=Physical Review Letters|language=en|volume=116|issue=22|issn=1079-7114}}</ref> The amount of [[energy]] released from the event was 50 times greater than the combined power of all the [[light]] from the [[Star|stars]] in the [[observable universe]].<ref>{{Cite web|last=Harwood|first=William|date=2016-02-11|title=Einste