Photo from the Nobel Foundation archive.
Albert Abraham Michelson
Born: 19 December 1852, Strelno (now Strzelno), Prussia (now Poland) (now Poland)
Died: 9 May 1931, Pasadena, CA, USA
Affiliation at the time of the award: University of Chicago, Chicago, IL, USA
Prize motivation: "for his optical precision instruments and the spectroscopic and metrological investigations carried out with their aid."
Prize share: 1/1
Interference means that several light waves with the same wavelength can strengthen or cancel out one another, depending on whether they are in phase with one another. In the mid-1880s Albert Michelson developed an interferometer, which uses a semi-transparent mirror to divide up a beam of uniform light waves. After routing the different waves through different channels, the light waves are recombined, and the difference in the distances covered leads to phase displacement, which generates patterns. The instrument is used to measure lengths as well as velocities of light with great precision.