Physics World announced that the 2016 Breakthrough of the Year goes to the LIGO Scientific Collaboration for “their revolutionary, first ever direct observations of gravitational waves”. LIGO stands for the Laser Interferometer Gravitational-wave Observatory.

“What’s been achieved by LIGO, particularly in a relatively short space of time, is truly incredible. The observations it has made are the first direct evidence of the existence of black holes, so LIGO has already changed our view of the universe,” said Physics World editor Hamish Johnston in a release.

LSU Department of Physics and Astronomy Professor Gabriela González, who is the international spokesperson for the 1,000-member LIGO Scientific Collaboration, accepted the recognition on behalf of the LIGO Scientific Collaboration. Physics World announced its top 10 breakthroughs of the year.

“We are very honoured to receive this recognition to not only a milestone discovery that has inspired the scientific community and the general public, but also to the teamwork that made it possible,” González was quoted as saying in a release.

On September 14, 2015, gravitational waves were detected when two black holes, one 36 times the mass of the Sun and the other 29 solar masses, collided and fused together to produce one huge black hole 62 times the mass of the Sun. The gravitational waves were produced 1.3 billion years ago and it happened 1.3 billion light-years away from Earth.

The black holes were 36 times and 29 times the mass of the Sun, but the fused black hole weighed only 62 solar masses and not 65 solar masses.  The three solar masses that went missing were what created the gravitational waves.

The gravitational waves were detected at 11:50 a.m. Central European Time on September 14, 2015. It was a chance discovery made during the experiment’s first observing run.  The upgraded version, Advanced LIGO, was to officially begin collecting data only from September 18, 2015.

Second time

Gravitational waves were detected for the second time on December 26, 2015. This event was also produced by colliding black holes.  But unlike the first one, the black holes were smaller in size — 14 and 8 solar masses. They merged to form a single black hole of 21 solar mass. The one missing solar mass went into creating the gravitational waves. The event happened some 1.4 billion light-years away.

Third time

In October 2015 LIGO recorded a third possible event, dubbed LVT151012. Although not statistically significant enough to be a discovery, the team believes this event also arose from two coalescing black holes.