Albert A. Michelson

His father kept a store in the mining camps. The family was Jewish and came from Strzelno, a town then in Prussia and now in Poland, and they sailed for America in 1855, when Albert was two years old. He grew up among prospectors at Murphy's Camp in California and Virginia City in Nevada, and spent his high school years in San Francisco in the house of an aunt. Passed over for a regular appointment to the Naval Academy in 1869, he took the case to Washington and put it to President Ulysses S. Grant himself. Grant created a special appointment for him. He graduated in 1873, went to sea for two years, and came back to Annapolis to teach physics and chemistry.

Physicists of the 1880s assumed light needed something to travel through, the way sound needs air. They called it the luminiferous ether, and it filled all of space. If it was there, the Earth was moving through it, and a beam of light sent along the direction of that motion should take measurably longer to come back than one sent across it. In 1887, at the Case School of Applied Science in Cleveland, Michelson and the chemist Edward Morley floated a stone slab on mercury, split a beam in two, and looked for the difference. There was none.

The experiment failed by its own terms. Michelson built an instrument to measure something and it measured nothing, and he treated that as a defeat rather than a discovery. He went back to it for decades, certain the ether was there and that he had simply not been precise enough. It is now the most consequential null result in physics: no ether meant no fixed stage against which motion could be measured, which cleared the ground for special relativity. Michelson himself was never at ease with relativity. In 1894 he told an audience in Chicago that the grand principles of physics were firmly established and that future discovery lay in the sixth place of decimals. He was quoting an eminent physicist he left unnamed. The line is routinely credited to Lord Kelvin, who appears never to have said it.

He died in Pasadena on May 9, 1931, with 36 of 233 planned runs of a final speed-of-light measurement completed. The Nobel had come in 1907, the first won by an American in any science, and it rewarded instruments rather than theory. He built the interferometer, measured the speed of light repeatedly across 50 years, fixed the standard metre against the wavelength of cadmium light, and in 1920 took the first measurement of a star's diameter other than the Sun's, Betelgeuse. Historians still argue over whether Einstein knew the 1887 result when he wrote the 1905 paper. Einstein said only that he took it for granted. The interferometer is now the instrument that detects gravitational waves.

Albert A. Michelson's life against the full span of the corpus.

• The Michelson interferometer invention
  Built in Helmholtz's laboratory in Berlin and first tried at Potsdam 1881
• The Michelson-Morley experiment discovery
  The null result that took the ether out of physics 1887
• The metre measured in wavelengths of cadmium light discovery
  Done at the request of the International Committee of Weights and Measures 1894
• Light Waves and Their Uses book
  His Chicago lectures on precision measurement as the future of physics 1903
• The stellar interferometer invention
  Mounted on the Hooker Telescope to size the star Betelgeuse 1920
• Studies in Optics book
  The last account of his own instruments and methods 1927

• December 19, 1852 aged 0 Born in Strzelno, Prussia, in what is now Poland His parents took him to the United States in 1855, when he was two.
• 1869 aged ~17 President Grant gives him a special appointment to the Naval Academy He had been passed over in the regular competition and argued his case in Washington.
• 1879 aged ~27 Publishes a speed of light of 299,910 kilometres per second Measured in a shed built along the sea wall at Annapolis in June and July.
• 1881 aged ~29 Tries his new interferometer in Berlin, then moves it to Potsdam Helmholtz had pointed him at the ether problem. Street traffic shook the fringes, so the apparatus went to the observatory outside the city.
• 1887 aged ~35 He and Edward Morley find no trace of the ether at Cleveland A stone slab floating on mercury, turned slowly while the fringes were read.
• 1892 aged ~40 Becomes the first head of physics at the new University of Chicago He had spent 1890 to 1892 at Clark University in Worcester. He stayed at Chicago until 1929.
• 1907 aged ~55 Awarded the Nobel Prize in Physics The first American to win a Nobel Prize in any science.
• 1920 aged ~68 Measures the diameter of Betelgeuse from Mount Wilson Working with Francis Pease. It was the first credible size for any star other than the Sun.
• May 9, 1931 aged 78 Dies in Pasadena, California His last speed of light experiment, run in a vacuum tube near Santa Ana, was finished by others and published in 1935.

• Ulysses S. Grant 1822–1885
  18th President and Union Army general whose leadership was decisive in winning the Civil War. appointed by
• Albert Einstein 1879–1955
  German-American theoretical physicist whose theory of relativity revolutionized modern physics. influenced
• Edwin Hubble 1889–1953
  Astronomer whose discovery of expanding galaxies provided the foundation for the Big Bang theory. shared Mount Wilson with