The journey began about 20 years ago. The Laser Interferometer Gravitational Wave Observatory (LIGO) was built in Handford, Washington, and Livingston, Louisiana, to detect and study the gravitational waves that Albert Einstein predicted in his theory of general relativity. But for nearly two decades, LIGO had nothing significant to show and little attention was given to the project.That was, until September 14, 2015, when American researchers got a call from their partners in Germany asking if the machines were not properly calibrated. A mere two days after firing up the first collaboration data run between LIGO and Virgo, a European interferometer near Pisa, Italy, the machines were gathering data that appeared to show that gravitational waves had been detected. The equipment was working just fine — and the first detection of gravitational waves was confirmed.The detection was announced in February 2016. It was an incredible moment for astrophysicists. But the general population, however, wasn’t sure what this announcement meant.Lisa Barsotti, now at the MIT Kavli Institute, was one of the researchers on this groundbreaking project. “When we first told people about it, pretty much nobody cared,” she says.It’s an understandable sentiment without the proper context.The gravitational wave detection came from a collision of two black holes millions of years ago. Detecting the energetic emission from that event was a revolutionary advance in science. LIGO was no longer an irrelevant project.“Everything changed so fast. It went from nobody really caring about LIGO, to being a part of this huge experiment that everybody wanted to talk about,” Barsotti says.The magnitude of this collision and the precision with which LIGO measured it at is the truly amazing aspect of this discovery. The equivalent of three times the mass of the sun was expelled in one-fifth of a second during the black hole merger. For perspective, in the last five billion years that the Sun has burned, it has lost only 0.03 percent of its mass.That collision pushed out extreme amounts of energy in the form of gravitational waves — like the waves caused when a boulder splashes into a pond — that propagated through space for millions of years.