Michelson, Albert Abraham

Michelson, Albert Abraham

Michelson, Albert Abraham, 1852-1931, American physicist, b. Strelno, Prussia, grad. Annapolis, 1873, and studied at Berlin, Heidelberg, and Paris. He was professor of physics at Clark Univ. (1889-92) and later was head of the department of physics at the Univ. of Chicago (1892-1931). He is known especially for his determinations of the speed of light; in some of his earliest work he tested the data of Foucault's experiments and, then and later, with apparatus (including the interferometer) that he designed and built himself, measured the speed of light to an unequaled degree of accuracy. He measured (1892-93) the length of the standard meter in Paris in terms of the wave length of the red line of the cadmium spectrum, using his interferometer method. The wave length thus provided an absolute and exactly reproducible standard of length. With E. W. Morley he conducted the Michelson-Morley experiment (1887), which failed to detect any difference in the speed of light caused by the motion of the earth through space. That led to the refutation of the ether hypothesis and contributed to the development of Einstein's theory of relativity. Michelson was the first to measure the diameter of a distant star. He also demonstrated that the earth as a whole is rigid, not molten. Awarded the 1907 Nobel Prize in Physics, he was the first American scientist to receive the honor. His major writings include Velocity of Light (1902) and Studies in Optics (1927).

See biography by his daughter, D. M. Livingston (1973).

(born Dec. 19, 1852, Strelno, Prussia—died May 9, 1931, Pasadena, Calif., U.S.) Prussian-born U.S. physicist. His family immigrated to the U.S. in 1854. He studied at the U.S. Naval Academy and in Europe and later taught principally at the University of Chicago (1892–1931), where he headed the physics department. He invented the interferometer, with which he used light to make extremely precise measurements. He is best remembered for the Michelson-Morley experiment, undertaken with Edward W. Morley (1838–1923), which established that the speed of light is a fundamental constant. Using a more refined interferometer, Michelson measured the diameter of the star Betelgeuse, the first substantially accurate determination of the size of a star. In 1907 he became the first American scientist to receive a Nobel Prize.

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Albert Abraham Michelson (December 19, 1852May 9, 1931) was a Polish-American physicist known for his work on the measurement of the speed of light and especially for the Michelson-Morley experiment. In 1907 he received the Nobel Prize in Physics. He became the first American to receive the Nobel Prize in sciences.

Biography

Michelson, the son of a Polish-Jewish merchant (father) and a Polish mother, was born to a Polish-Jewish family in what is today Strzelno, Poland (then Strelno, Provinz Posen in the Kingdom of Prussia). He moved to the United States with his parents in 1855, when he was two years old. He grew up in the rough mining towns of Murphy's Camp, California and Virginia City, Nevada, where his father was a merchant. He spent his high school years in San Francisco in the home of his aunt, Henriette Levy (née Michelson), who was the mother of author Harriet Lane Levy.

President Ulysses S. Grant awarded Michelson a special appointment to the U.S. Naval Academy in 1869. During his four years as a midshipman at the Academy, Michelson excelled in optics, heat and climatology as well as drawing. After his graduation in 1873 and two years at sea, he returned to the Academy in 1875 to become an instructor in physics and chemistry until 1879. From 1880 to 1882, Michelson undertook postgraduate study at Berlin under Hermann Helmholtz and at Paris.

Michelson was fascinated with the sciences and the problem of measuring the speed of light in particular. While at Annapolis, he conducted his first experiments of the speed of light, as part of a class demonstration in 1877. After two years of studies in Europe, he resigned from the Navy in 1881. In 1883 he accepted a position as professor of physics at the Case School of Applied Science in Cleveland, Ohio and concentrated on developing an improved interferometer. In 1887 he and Edward Morley carried out the famous Michelson-Morley experiment which seemed to rule out the existence of the aether. He later moved on to use astronomical interferometers in the measurement of stellar diameters and in measuring the separations of binary stars.

In 1889 Michelson became a professor at Clark University at Worcester, Massachusetts and in 1892 was appointed professor and the first head of the department of physics at the newly organized University of Chicago.

In 1899, he married Edna Stanton and they raised one son and three daughters.

In 1907, Michelson had the honor of being the first American to receive a Nobel Prize in Physics "for his optical precision instruments and the spectroscopic and metrological investigations carried out with their aid". He also won the Copley Medal in 1907, the Henry Draper Medal in 1916 and the Gold Medal of the Royal Astronomical Society in 1923. A crater on the Moon is named after him.

Michelson died in Pasadena, California at the age of 78. The University of Chicago Residence Halls remembered Michelson and his achievements by dedicating Michelson House in his honor. Case Western Reserve has also dedicated a Michelson House to him, and an academic building at the United States Naval Academy also bears his name. Michelson Laboratory at Naval Air Weapons Station China Lake in Ridgecrest, California is named after him. There is an interesting display in the publicly accessible area of the Lab of Michelson's Nobel Prize medal, the actual prize document, and examples of his diffraction gratings.

Speed of light

Early measurements

As early as 1877, while still serving as an officer in the US Navy, Michelson started planning a refinement of the rotating-mirror method of Léon Foucault for measuring the speed of light, using improved optics and a longer baseline. He conducted some preliminary measurements using largely improvised equipment in 1878 about which time his work came to the attention of Simon Newcomb, director of the Nautical Almanac Office who was already advanced in planning his own study. Michelson published his result of 299,910±50 km/s in 1879 before joining Newcomb in Washington DC to assist with his measurements there. Thus began a long professional collaboration and friendship between the two.

Simon Newcomb, with his more adequately funded project, obtained a value of 299,860±30 km/s, just at the extreme edge of consistency with Michelson's. Michelson continued to "refine" his method and in 1883 published a measurement of 299,853±60 km/s, rather closer to that of his mentor.

Mount Wilson and Lookout Mountain

In 1906, a novel electrical method was used by E. B. Rosa and N. E. Dorsey of the National Bureau of Standards to obtain a value for the speed of light of 299,781±10 km/s. Though this result has subsequently been shown to be severely biased by the poor electrical standards in use at the time, it seems to have set a fashion for rather lower measured values.

From 1920, Michelson started planning a definitive measurement from the Mount Wilson Observatory, using a baseline to Lookout Mountain, a prominent bump on the south ridge of Mount San Antonio (Old Baldy), some 22 miles distant.

In 1922, the U.S. Coast and Geodetic Survey began two years of painstaking measurement of the baseline using the recently available invar tapes. With the baseline length established in 1924, measurements were carried out over the next two years to obtain the published value of 299,796±4 km/s.

"A Geodetic Measurement of Unusually High Accuracy" by Captain C.L. Garner of this baseline survey and measurement can be found at:

http://www.pvaa.us/nightwatch/GeodeticMeasurementOfUnusuallyHighAccuracy.pdf

Famous as the measurement is, it was beset by problems, not least of which was the haze created by the smoke from forest fires which blurred the mirror image. It is also probable that the intensively detailed work of the Geodetic Survey, with an estimated error of less than one part in 1 million, was compromised by a shift in the baseline arising from the Santa Barbara earthquake of 29 June 1925 which was an estimated magnitude of 6.3 on the Richter scale.

Michelson, Pease & Pearson

The period after 1927 marked the advent of new measurements of the speed of light using novel electro-optic devices, all substantially lower than Michelson's 1926 value.

Michelson sought another measurement but this time in an evacuated tube to avoid difficulties in interpreting the image owing to atmospheric effects. In 1930, he began a collaboration with Francis G. Pease and Fred Pearson to perform a measurement in a 1.6 km tube at Pasadena, California. Michelson died with only 36 of the 233 measurement series completed and the experiment was subsequently beset by geological instability and condensation problems before the result of 299,774±11 km/s, consistent with the prevailing electro-optic values, was published posthumously in 1935.

Interferometry

In 1887 he collaborated with colleague Edward Williams Morley in the Michelson-Morley experiment. Their experiment for the expected motion of the Earth relative to the aether, the hypothetical medium in which light was supposed to travel, resulted in a null result. Though it may appear that Albert Einstein did not know of the work, it gave a boost to the acceptance of the theory of relativity.

Astronomical interferometry

From 1920 and into 1921 Michelson and Francis G. Pease became the first individuals to measure the diameter of a star other than the Sun. They used an astronomical interferometer at the Mount Wilson Observatory to measure the diameter of the super-giant star Betelgeuse. A periscope arrangement was used to obtain a densified pupil in the interferometer, a method later investigated in detail by Antoine Émile Henry Labeyrie for use in with "Hypertelescopes". The measurement of stellar diameters and the separations of binary stars took up an increasing amount of Michelson's life after this.

Michelson in popular culture

In an episode of the television series Bonanza (Look to the Stars, broadcast March 18, 1962), Ben Cartwright (Lorne Greene) helps the 16-year-old Albert Abraham Michelson (portrayed by 25-year-old Douglas Lambert (1936-1986)) obtain an appointment to the U.S. Naval Academy, despite the opposition of the anti-semitic town schoolteacher, William Schallert. Bonanza was set in and around Virginia City, Nevada, where Michelson lived with his parents prior to leaving for the Naval Academy. In the postscript to the episode, Greene mentions Michelson's 1907 Nobel Prize.

The home in which Michelson lived as a child in Murphys Camp, California is now a tasting room for Twisted Oak Winery.

Michelson House in Shoreland Hall, an undergraduate dorm at The University of Chicago, is named after him.

Michelson House, an undergraduate residence hall at Case Western Reserve University in Cleveland, Ohio, is named after him.

Honours and awards

See also

Notes

References

External links

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