MICHELSON, ALBERT ABRAHAM
MICHELSON, ALBERT ABRAHAM (1852–1931), U.S. physicist; the first American to be awarded a Nobel Prize for science. He was born in Strelno, Prussia, and was taken by his family to the United States at the age of two. Michelson graduated from the naval academy at Annapolis in 1873. However, after spending two years at sea he resigned to become an instructor in physics at the naval academy (1875–79). He spent a year in Washington and then two years studying in Germany. He returned to the U.S. in 1883 to become professor at the Case School of Applied Science in Cleveland until 1889. From 1889 to 1892 he was at Clark University and finally he was professor at the University of Chicago (1892–1929). He was awarded the Nobel Prize in physics in 1907. Michelson was a remarkable experimentalist able to secure astonishing accuracies with the simplest apparatus. His lifelong interest was the velocity of light, and this was the subject of his first experiment even in his mid-20s when he was an instructor at the U.S. naval academy at Annapolis. At that time physicists believed in the existence of an ether that filled all space, was at absolute rest, and through which light traveled in waves. There was then no way of measuring the motion of any body relative to the ether and leading scientists doubted whether this could be done. If it could be measured, two beams of light should show interference fringes denoting the difference. By measuring the width of the fringes it should be possible to show the earth's exact velocity when compared with the ether. Not only would the earth's absolute motion be determined, but also that of all bodies in the planetary system whose motions relative to the earth were known. For his experiment Michelson developed the interferometer, an instrument now used to measure wavelengths of light and other wavelengths of the radiation spectrum. He carried out his first experiments in Berlin in 1881 in Helmholtz' laboratory. In 1887, together with Edward Williams Morley, he performed one of the most important experiments in the history of science, which provided a new starting point for the great theoretical developments in 20th-century physics. The conclusion of the experiment indicated that light travels with the same velocity in any direction under any circumstances, and the implication was that the ether did not exist. This became one of the basic concepts which led *Einstein in 1905 to his special theory of relativity. The proving of this revolutionary theory of the absolute speed of light under any conditions has become the underlying principle of modern physics, astronomy, and cosmology and is considered to be, perhaps, the one absolute natural law in the universe. As a great experimentalist, Michelson established in 1892/93 the meter in terms of the wavelength of cadmium. He also determined the diameter of Jupiter's satellites and was the first person to measure the dimension of a star, Alpha Orion. Michelson wrote Velocity of Light (1902), Light Waves and Their Uses (1903), and Studies in Optics (1927).