Michelson's interferometer design. Diagram and equations used by US physicist Albert Abraham Michelson (1852-1931) when carrying out his interferometry experiments in the period 1878-9 while an instructor at the US Naval Academy, Annapolis, Maryland, USA. These were among his first interferometry experiments. The interferometer bounced light between mirrors to measure the speed of light (value given at lower right: 186,000 miles per second). Michelson's later work with Morley (Michelson-Morley experiment of 1887) tested Einstein's theory of relativity. Michelson was awarded the 1907 Nobel Prize in Physics for his interferometry work.