Sunday, February 4, 2018

The A A Michelson Speed of Light Experiment

Albert A. Michelson (1852-1931) was known for his experiments for measuring the speed of light. Here is a short summary of what he did from The University of Chicago.
A master at the art of measurement, Michelson devised experiments noted for their simplicity. Thus measurements of the velocity of light used a rapidly rotating, multifaceted mirror to reflect a beam of light. When the speed was correctly adjusted, light reflected from the rotating mirror struck a mirror held in a fixed position and returned to strike the next face on the spinning mirror. The time needed for the next face to rotate into position to precisely reflect the light was the time required for the light to travel the known distance to the stationary mirror and back. His earliest attempts, made with materials costing barely ten dollars, measured the speed of light at 186,508 miles per second, or within two hundred miles of the actual value.
Above is one of the mirrors used by Michelson. Michelson attended the Naval Academy and the apparatus is in the Naval Academy Museum.  Here is a link to a short biography of Michelson from the Wikipedia article about his life.

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