Albert A. Michelson
|Died||May 9, 1931 (aged 78)|
|Alma mater||United States Naval Academy|
University of Berlin
|Known for||Speed of light|
Michelson stellar interferometer
Margaret Hemingway; 3 children
(m. 1877; div. 1898)
Edna Stanton (m. 1899); 3 children
|Awards||Matteucci Medal (1903)|
Nobel Prize in Physics (1907)
Copley Medal (1907)
Elliott Cresson Medal (1912)
Henry Draper Medal (1916)
Albert Medal (1920)
Franklin Medal (1923)
Duddell Medal and Prize (1929)
|Institutions||Case Western Reserve University|
University of Chicago
|Doctoral advisor||Hermann Helmholtz|
|Other academic advisors||Georg Hermann Quincke|
|Doctoral students||Robert Millikan|
Albert Abraham Michelson FFRS HFRSE (December 19, 1852 – May 9, 1931) was an American physicist known for his work on measuring the speed of light and especially for the Michelson–Morley experiment. In 1907 he received the Nobel Prize in Physics, becoming the first American to win the Nobel Prize in a science. He was the founder and the first head of the physics department of the University of Chicago.
Michelson was born in Strzelno, Province of Posen in now Poland (under German occupation), the son of Samuel Michelson, a Jewish merchant and his wife, Rozalia Przyłubska, a daughter of a Polish merchant. He moved to the US with his parents in 1855, at the age of two. He grew up in the mining towns of Murphy's Camp, California and Virginia City, Nevada, where his father was a merchant. His family was Jewish by birth but non-religious, and Michelson himself was a lifelong agnostic. 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, climatology and drawing. After graduating in 1873 and two years at sea, he returned to the Naval Academy in 1875 to become an instructor in physics and chemistry until 1879. In 1879, he was posted to the Nautical Almanac Office, Washington (part of the United States Naval Observatory), to work with Simon Newcomb. In the following year he obtained leave of absence to continue his studies in Europe. He visited the Universities of Berlin and Heidelberg, and the Collège de France and École Polytechnique in 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 on the speed of light, as part of a class demonstration in 1877. His Annapolis experiment was refined, and in 1879, he measured the speed of light in air to be 299,864 ± 51 kilometres per second, and estimated the speed of light in vacuum as 299,940 km/s, or 186,380 mi/s. 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 failed to detect evidence of the existence of the luminiferous ether. 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 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 dedicated a Michelson House to him, and Michelson Hall (an academic building of science classrooms, laboratories and offices) at the United States Naval Academy also bears his name. Michelson Laboratory at Naval Air Weapons Station China Lake in Ridgecrest, California is named for him. There is a display in the publicly accessible area of the Lab which includes facsimiles of Michelson's Nobel Prize medal, the prize document, and examples of his diffraction gratings.
Numerous awards, lectures, and honors have been created in Albert A. Michelson's name. Some of the current awards and lectures named for Michelson include the following: the Bomem-Michelson Award and Lecture annually presented until 2017 by the Coblentz Society; the Michelson–Morley Award and Lecture, along with the Michelson Lecture Series, and the Michelson Postdoctoral Prize Lectureship, all of which are given annually by Case Western Reserve University; the A.A. Michelson Award presented every year by the Computer Measurement Group; the Albert A. Michelson Award given by the Navy League of the United States; and the Michelson Memorial Lecture Series presented annually by the Division of Mathematics and Science at the U.S. Naval Academy.
In 1899, he married Edna Stanton. They raised three daughters.
Michelson was fascinated by light all his life. Once asked why he studied light, he said, ‘’because it’s so much fun.’’ 
As early as 1869, while serving as an officer in the United States Navy, Michelson started planning a repeat 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 the same time that 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's formal experiments took place in June and July 1879. He constructed a frame building along the north sea wall of the Naval Academy to house the machinery. 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.
In 1906, a novel electrical method was used by E. B. Rosa and 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.
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 June 29, 1925, which was an estimated magnitude of 6.3 on the Richter scale.
The now-famous Michelson–Morley experiment also influenced the affirmation attempts of peer Albert Einstein's theory of general relativity and special relativity, using similar optical instrumentation. These instruments and related collaborations included the participation of fellow physicists Dayton Miller, Hendrik Lorentz, and Robert Shankland.
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 1929, he began a collaboration with Francis G. Pease and Fred Pearson to perform a measurement in a 1.6 km tube 3 feet in diameter at the Irvine Ranch near Santa Ana, California. In multiple reflections the light path was increased to 5 miles. For the first time in history the speed of light was measured in an almost perfect vacuum of 0.5 mm of mercury. 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.
During June and early July 1879, Michelson refined experimental arrangements from those developed by Hippolyte Fizeau and Léon Foucault. The experimental setup was as follows: Light generated from a source is directed towards a rotating mirror through a slit on a fixed plate; the rotating mirror reflects the incoming light and at a certain angle, towards the direction where another fixed flat mirror is placed whose surface is perpendicular to the incoming ray of light; the rotating mirror should have rotated by an angle α by the time the ray of light travels back and is reflected again towards the fixed plate (the distance between the fixed mirror and the rotating one is recorded as D); a displacement from the slit is detected on the plate which measures d; the distance from the rotating mirror to the fixed plate is designated as the radius r while the number of revolutions per second of the mirror is recorded as ω. In this way, tan(2α) = d/r; Δt = (α/2π)/ω; speed of light can be derived as c = 2D/Δt.
While at plain sight, four measured quantities are involved: distance D, radius r, displacement d and rotating mirror revolution per second ω, which seems simple; yet based on the limitation of the measurement technology at that time, great efforts were made by Michelson to reduce systematic errors and apply subsequent corrections. For instance, he adopted a steel measuring tape with a said length of 100 feet and he intended to measure tens of times across the distance; still, he measured its length against a copy of the official standard yard to find out it as 100.006 feet, thus eliminating a systematic error, albeit small.
Aside from the efforts to reduce as much as possible the systematic errors, repeated measurements were performed at multiple levels to obtain more accurate results. As R.J.MacKay and R.W.Oldford remarked in their article, ‘It is clear that Michelson appreciated the power of averaging to reduce variability in measurement’, it is clear that Michelson had in mind the property that averages vary less which should be formally described as: the standard deviation of the average of n independent random variables is less than that of a single random variable by a factor of the square root of n. To realize that, he also strived to have each measurement not influencing each other, thus being mutually independent random variables.
It should also be noted about the statistical model for repeated measurements where the assumption of independence or identical distributions is unrealistic. In the case of light speed study, each measurement is approached as the sum of quantity of interest and measurement error. In the absence of systematic error, the measurement error of speed of light can be modeled by a random sample from a distribution with unknown expectation and finite variance; thus, the speed of light is represented by the expectation of the model distribution and the ultimate goal is to estimate the expectation of the model distribution on the acquired dataset. The law of large numbers suggests to estimate the expectation by the sample mean.
In 1887 he collaborated with colleague Edward Williams Morley of Western Reserve University, now part of Case Western Reserve University, 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. Surprised, Michelson repeated the experiment with greater and greater precision over the next years, but continued to find no ability to measure the aether. The Michelson–Morley results were immensely influential in the physics community, leading Hendrik Lorentz to devise his now-famous Lorentz contraction equations as a means of explaining the null result.
There has been some historical controversy over whether Albert Einstein was aware of the Michelson–Morley results when he developed his theory of special relativity, which pronounced the aether to be "superfluous." In a later interview, Einstein said of the Michelson–Morley experiment, "I was not conscious it had influenced me directly... I guess I just took it for granted that it was true." Regardless of Einstein's specific knowledge, the experiment is today considered the canonical experiment in regards to showing the lack of a detectable aether.
The precision of their equipment allowed Michelson and Morley to be the first to get precise values for the fine structure in the atomic spectral lines for which in 1916 Arnold Sommerfeld gave a theoretical explanation, introducing the fine-structure constant.
In 1920 Michelson and Francis G. Pease made the first measurement of the diameter of a star other than the Sun. Michelson had invented astronomical interferometry and built such an instrument at the Mount Wilson Observatory which was used to measure the diameter of the red giant Betelgeuse. A periscope arrangement was used to direct light from two subpupils, separated by up to 20 feet (6m), into the main pupil of the 100 inch (2.5m) Hooker Telescope, producing interference fringes observed through the eyepiece. The measurement of stellar diameters and the separations of binary stars took up an increasing amount of Michelson's life after this.
Beginning in the 1970s, astronomical interferometry has been revived, with the configuration using two (or more) separate apertures (with diameters small compared to their separation) being often referred to as "Michelson Stellar Interferometry." This was to distinguish it from speckle interferometry, but should not be confused with the Michelson interferometer which is one common laboratory interferometer configuration of which the interferometer used in the Michelson–Morley experiment was an instance. Michelson's concept of interfering light from two relatively small apertures separated by a substantial distance (but with that distance, or baseline, now often as long as hundreds of meters) is employed at modern operational observatories such as VLTI, CHARA and the U.S. Navy's NPOI.
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 Michelson (portrayed by 25-year-old Douglas Lambert (1936–1986)) obtain an appointment to the U.S. Naval Academy, despite the opposition of the bigoted town schoolteacher (played by 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 a voice-over at the end of the episode, Greene mentions Michelson's 1907 Nobel Prize.
New Beast Theater Works in collaboration with High Concept Laboratories produced a 'semi-opera' about Michelson, his obsessive working style and its effect on his family life. The production ran from February 11 to February 26, 2011 in Chicago at The Building Stage. Michelson was portrayed by Jon Stutzman. The play was directed by David Maral with music composed by Joshua Dumas.
Norman Fitzroy Maclean wrote an essay "Billiards is a Good Game"; published in The Norman Maclean Reader (ed. O. Alan Weltzien, 2008), it is an appreciation of Michelson from Maclean's vantage point as a graduate student regularly watching him play billiards.
Michelson was a member of the Royal Society, the National Academy of Sciences, the American Physical Society and the American Association for the Advancement of Science.
Michelson's biographers stress, that our hero was not conspicuous by religiousness. His father was a free-thinker and Michelson grew up in non-religious family and have no opportunity to acknowledge the belief of his forebears. He was agnostic through his whole life and only for the short period he was a member of the 21st lodge in Washington.
Morley was deeply religious. His original training had been in theology and he only turned to chemistry, a self-taught hobby, when he was unable to enter the ministry. Michelson, by contrast, was a religious agnostic.
On the religious question, Michelson disagreed with both these men. He had renounced any belief that moral issues were at stake in ...CS1 maint: numeric names: authors list (link)
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