In 1887, Albert Michelson built an experiment that he hoped would lead to the detection of luminiferous ether. At the time, physicists believed that the ether permeated the universe and served as the medium through which light waves moved, like the way waves traveled across the ocean.*
The experiment turned out to be a failure. The mystical ether didn’t exist. But the instrument that Michelson invented to conduct this research would detect, more than a century later, a very real, very significant astronomical phenomenon: gravitational waves, the ripples in the fabric of space and time, coming from a violent collision between two black holes.
Scientists at the Laser Interferometer Gravitational-Wave Observatory, or LIGO, used Michelson’s invention to make the first-ever direct observation of gravitational waves in September 2015. Albert Einstein predicted the existence of gravitational waves in 1916 as part of his general theory of relativity, but no one had detected them directly. Since their first find, the LIGO scientists have detected the waves three more times. On Tuesday, they were awarded the Nobel prize in physics for their efforts.
The instrument at the heart of Michelson’s research is called an interferometer, which manipulates light inside closed tubes to make tiny measurements of natural phenomena. At LIGO’s twin observatories in Washington state and Louisiana, scientists use laser light.