The first detection of gravitational waves was in November 2015, a century after Albert Einstein’s General Theory of Relativity predicted their existence. It was a discovery of such importance that the Nobel prize for physics was awarded for it soon after in 2017. But since then there have been a flurry of such waves that are caused by the collisions of massive stellar objects.
Scientists have identified four more ghostly signals of massive collisions in outer space, including of the largest to date, bringing their total haul of gravitational-wave detections to 11 in just a few years.
A team of researchers affiliated with the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the U.S. and its European counterpart Virgo unveiled the four new detections on Saturday (Dec. 1) at a scientific meeting.
Gravitational waves are often described as “ripples in space-time” and are produced by pairs of black holes or neutron stars—which are two forms of extremely massive, dense remnants created when a star explodes. Pairs of these objects orbit each other, drawing ever closer to one another and causing gravitational waves to ripple outward as they do so, until they eventually collide.
The newly announced gravitational-wave observations weren’t found in new data—in fact, both LIGO and Virgo have been down for upgrades since August 2017.
Instead, the new detections were found on another look through data gathered during the observing run that took place between Nov. 30 and Aug. 25, 2017. Scientists had already published three black hole mergers observed during that time frame, as well as the sole binary neutron star collision discovered to date.
It is strange to think that such a major discovery has become somewhat routine in just a few years. But that is often how science is. As has been said, yesterday’s major discovery is today’s background.