The Michelson Interferometer

The Theory of Special Relativity

The experiment's results left physicists stunned for many years; and some of them postulated that the ether, while real, simply wasn't observable.

Albert Einstein took a brave step forward with the publication of his theory of special relativity in 1906. In his theory, he argued that if there were no experimental proof of the ether, then the simplest explanation was that it did not exist. He went on to conclude that as there was no ether to slow down light, the speed of light was constant in a vacuum.

In his theory, Einstein developed a new understanding of space and time. He spent the next decade expanding and generalizing his theory and received the Nobel Prize in 1921.

Source: Library of Congress Albert Einstein Albert Einstein

©2012 WGBH Educational Foundation. All Rights Reserved. Adapted from PlanetQuest: "SIM Lite Astrometric Observatory"/NASA/JPL. Images courtesy of Archival Photographic Files, apf6-00086, Special Collections Research Center, University of Chicago Library, and Library of Congress.