L is for Laser Interferometer Gravitational-Wave Observatory

First Detection of Gravitational Waves from Neutron-Star Crash Marks New Era of Astronomy
Albert Einstein first predicted the existence of gravitational waves in his theory of general relativity, which was published in 1916. But it took a century for astronomers to detect them directly. That milestone came in September 2015, when LIGO saw gravitational waves emitted by two merging black holes.
https://www.space.com/38469-gravitational-waves-from-neutron-stars-discovery-ligo.html