Albert A. Michelson - Career and Influence

Albert A. Michelson

Career and Influence

Adapted from an article from the

Nimitz Library at the United States Naval Academy

Albert A. Michelson is renowned for his experiments and precise determinations of the:

• velocity of light,
• ether drift,
• length of the standard meter,
• spectral lines,
• diameters of stars, and
• rigidity of the earth.

Additionally, Michelson invented different types of instruments to help carry out these experiments. He is best known for his invention of:

• the interferometer,
• the harmonic analyzer (with S.W. Stratton),
• the echelon spectroscope, and
• ruling engines.

Michelson accomplished his research and inventions in the course of his teaching career as a professor of physics at various institutions of higher education. Michelson’s teaching career:

• 1875, December. Instructor of physics and chemistry at the Naval Academy.
• 1879 aided Simon Newcomb in his experiments with the velocity of light at the Nautical Almanac Office.
• 1880 - 1882. Graduate studies (exchange professor) in Berlin, Heidelberg, and Paris.
• 1882 - 1889. Instructor in physics at the then newly established Case School of Applied Science.
• 1889 - 1892. First Chair of Physics at Clark University in Worcester, Massachusetts.
• 1892 - 1930. Professor and first Head of the Department of Physics at the University of Chicago.

The velocity of light is so enormously greater than anything with which we are accustomed to deal that the mind has some little difficulty in grasping it. we can, perhaps, give a better idea of this velocity by saying that light will travel around the world seven times between two ticks of a clock. -- Albert A. Michelson, Light Waves and their Uses (1903), p.146

At the University of Chicago he was one of the first physicists to occupy the Ryerson Physical Laboratory, which would eventually employ a number of Nobel Laureates and later become known as the home of the "Manhattan Project." He officially retired from teaching in 1930, having received the first "Distinguished Service Professor" award by the University in 1925.

It was during his days as an instructor at the Naval Academy that Michelson conducted his first velocity of light experiments as a part of  a class demonstration in 1877. He made an important modification of Foucault's earlier method for determining the velocity of light. He contributed ten dollars of his own money for a revolving mirror, which enabled him to complete the experiment successfully.

Michelson's measurements of the velocity of light:

• 299,853 +/- 60 (km/sec) in 1882 at Case.
• 299,796 +/-   4 (km/sec) in 1926 at Mount Wilson.
• 299,774 +/- 11 (km/sec) In 1929 at Irvine Ranch in California.

His 1926 measurement is still considered the most accurate result obtained using optical techniques. The final results of the 1929 experiment were determined in 1933, two years after Michelson's death, by his long-time associate Fred Pearson and astronomer F. G. Pease.

Some of Michelson's other significant discoveries include:

• 189x, the length of the standard meter (used as the standard length from 1893-1960),
• 1919, the rigidity and elasticity of the earth, and
• 1920, the first measurement of the angular diameter of a star ("Betelgeuse" of  the constellation Orion).

He also studied the metallic colors in birds and insects.

In everything he  did, whether it was work or play, he was an artist; he took equal delight in finding the cause of the iridescence of the butterfly's wing and in conducting the ether-drift experiments by which laid the experimental foundation for the theory of relativity. To him values were  not measured by the acclaim of the world. To his friends he was like the sea on a summer's day-serene, illimitable, unfathomable. -- Albert Einstein

In addition to his research and teaching, over seventy-five  of Michelson's articles and lectures were published, along with three of his books:

• Determination Experimentale de la Valuer du Metre en Longueurs d'Ondes Lumineuses (1894),
• Light Waves and Their Uses (1903) and
• Studies in Optics (1927).

Michelson's report conveying the results of his experiment at the U. S. Naval Academy in 1879, "Experimental Determination of the Velocity of Light", was also later published in 1880.

Throughout his career, Michelson taught and inspired people who would  themselves become successful teachers, physicists, and inventors. His most indelible sphere of influence existed at the University of Chicago.  Notable scientists collaborated with Michelson on various projects while making a name for themselves in their respective fields.

• S.W. Stratton, who later became Director of the National Bureau of Standards and President of the Massachusetts Institute of Technology, helped Michelson with teaching as  well as with the invention and development of the Michelson-Stratton harmonic analyzer.
• George Ellery Hale, who became a famous astrophysicist noted for his discoveries about the surface of the sun, was a colleague of Michelson's in the Physics Department; while at the University of Chicago he organized the Yerkes Observatory and from 1904-1923 also organized and directed the Mount Wilson Observatory.
• Robert A. Millikan,  a Michelson student and later one of his faculty members, became the second American to win the Novel Prize in Physics in 1923. He was well known for his research of electricity, optics, and molecular physics.
• Arthur Holly Compton, also a faculty member in Michelson's department at  Chicago, became the third American physicist to win the Nobel Prize in Physics in 1927. He was recognized for his work on cosmic rays, atomic energy, and the Compton effect.