Albert Abraham Michelson was born in the Prussian town of Strelno (now Strzelno, Poland) on Dec. 19, 1852. His parents brought him to the United States in 1854 and settled in San Francisco, Calif.

Michelson’s extraordinary scientific talents were recognized early. In 1878 Michelson began work on what was to be the passion of his life – the accurate measurement of the speed of light. He traveled to Europe in 1880 to study optics and spent two years there. Upon his return to the United States, he determined the velocity of light to be 299,853 kilometers per second, a value that remained the best available until Michelson himself recalculated it shortly before his death.

In Europe, Michelson began constructing an interferometer, a device that splits a beam of light in two, sends the parts along different paths, then brings them back together. If the light waves had, in the interim, fallen out of step, interference fringes, or alternating light and dark bands, would be obtained. From the width and number of those fringes, extremely accurate measurements could be made.

The interferometer was used by Michelson and American chemist and physicist Edward Williams Morley to perform their famous Michelson-Morley experiment, an attempt to measure the Earth’s velocity relative to the ether (a material then thought to occupy all space outside the Earth’s atmosphere). The results, announced in 1887, were negative; there was apparently no motion of the Earth relative to the ether. There was, therefore, no ether. It was perhaps the most significant negative experiment in the history of science. In terms of classical Newtonian physics, the results were paradoxical, and in order to explain them, physics had to be recast on an entirely new foundation. This necessity eventually resulted in Albert Einstein’s formulation of the theory of relativity in 1905.

In 1923 Michelson returned to the problem of the accurate measurement of the velocity of light. He conducted two separate experiments to measure the time required for a beam of light to travel between two fixed points. Michelson died before the results of his final tests could be evaluated, but in 1933 the figure was announced as 299,774 kilometers per second – a value only about 18 kilometers per second lower than the value arrived at in the 1980s: 299,792.46 kilometers per second.

According to Source of photos: internet