Michelson, Albert Abraham 1852-1931

MICHELSON, ALBERT ABRAHAM 1852-1931

Physicist and first american nobel prize winner

Background

Albert Abraham Michelson was born in Prussia, in 1852, immigrating with his family at the age of four first to Panama and then to San Francisco, where his father became an itinerant merchant serving the mining camps of the Gold Rush days. He was sent to boarding school where he developed an interest in science and, after an interview in 1869 with President Ulysses Grant, was appointed to the Naval Academy at Annapolis. Upon graduation he was named physics instructor at the academy. He became interested in the speed of light and how to measure it accurately. As a result he was granted a leave of absence, which permitted him to spend 1880 to 1882 in Europe, much of the time in the physics laboratory of Hermann von Helmholtz in Berlin.

The Velocity of Light

The problem of measuring the speed of light had both practical and theoretical aspects. Under the then-current theory, space was filled with an invisible substance known as the ether, through which light waves were thought to be propagated. Michelson's working hypothesis was that inasmuch as the ether is at rest and the earth moves through it, the speed of light on the earth's surface should be affected by the density and flow of the ether. In Helmholtz's laboratory (and with the financial assistance of Alexander Graham Bell) he designed an instrument called the interferential refractometer (later shortened to interferometer), which he could use to test the existence of the ether by comparing beams of light reflected in opposite directions.

The Michelson-Morley Experiment

In 1881 Michelson resigned from active duty in the navy and was appointed professor of physics at the Case Institute of applied Science in Cleveland, Ohio. In 1885 he began a collaboration with physicist Edward W. Morley of Western Reserve University to test for the relative motion of the earth with respect to a presumably stationary ether. The experiment was painstaking because of the problems arising from measuring an extraterrestrial phenomenon under terrestrial conditions. The interferometer had to be carefully mounted on a sandstone slab that rested on a mercury bearing. The results of the experiments were negative: no difference in the velocity of light could be detected no matter how a light beam might be rotated with respect to the ether.

Michelson in Chicago

Having become an internationally recognized expert in precision measurement, Michelson was named chairman of the Department of Physics at the University of Chicago in 1893. There he built new precision instruments and turned to spectroscopy, the measurement and analysis of stellar spectra to determine the chemical components of stars. In 1899 he gave the Lowell Lectures at Harvard in which he stated that the more important fundamental laws and facts of physical science have all been discovered, and these are now so firmly established that the possibility of their ever being supplanted in consequence of new discoveries is exceedingly remote. In retrospect, Michelson's remarks constitute an odd capstone to the Newtonian era, just before the quantum and relativity revolutions broke upon the complacent world of academic physics.

Einstein, Michelson, and Relativity

In 1905 Albert Einstein demonstrated in the special theory of relativity that the speed of light was constant and therefore the ether did not exist. Einstein was later unable to recall whether he had read or heard of the Michelson-Morley experiment before then, but in light of his theory it quickly became apparent that Michelson and his colleague had in fact demonstrated the nonexistence of the ether even though they had not recognized it. Toward the end of his life Michelson spoke fondly of "the beloved old aether" and remained skeptical of Einstein's theory, although open to its possibility. In 1907 he became the first American to win the Nobel Prize, awarded to him for his invention of precision optical instruments and for the various experiments he had conducted with them.

Last Years

Michelson returned to the navy during World War I and contributed to a variety of technical projects, especially the optical range finder. In the 1920s he supervised experiments at Mount Wilson Observatory in California, including an optical determination of the velocity of light between two mountain peaks (Mount Wilson to Mount San Antonio). He died in Pasadena on 9 May 1931.

Source:

Loyd S. Swenson Jr., The Ethereal Aether: A History of the Michelson-Morley-Miller Aether-Drift Experiments, 1880-1930 (Austin: University of Texas Press, 1972).