| Alexander Friedmann | |
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Alexander Friedmann
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| Born | June 16, 1888 Saint Petersburg |
| Died | September 16, 1925 (aged 37) Leningrad |
| Nationality | Russian |
| Fields | physical cosmology meteorology hydrodynamics |
| Institutions | Perm State University Petrograd Polytechnical Institute Main Geophysical Observatory |
| Doctoral advisor | Vladimir Steklov |
| Doctoral students | George Gamow Nikolai Kochin Pelageya Polubarinova-Kochina |
| Known for | Friedmann equations Friedmann–Lemaître–Robertson–Walker metric Friedmann–Keller chain |
Alexander Alexandrovich Friedmann (also spelled Friedman or Friedman, Russian: Алекса́ндр Алекса́ндрович Фри́дман) (June 16, 1888, Saint Petersburg, Russian Empire – September 16, 1925, Leningrad, USSR) was a Russian and Soviet physicist and mathematician.
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Alexander Friedmann was born to the composer and ballet dancer Alexander Friedmann (who was a son of baptized Jewish cantonist) and the pianist Ludmila Voyachek. He lived much of his life in Saint Petersburg. He fought in World War I (on behalf of Imperial Russia) as a bomber and later lived through the Russian Revolution of 1917.
Friedmann obtained his degree in St. Petersburg State University (1910), became a lecturer in St.-Petersburg State College of Mines, and a professor in Perm State University in 1918.
In June 1925 he was given the job of the director of Main Geophysical Observatory in Leningrad. In July 1925 he participated in a record-setting balloon flight, reaching the elevation of 7,400 m (24,300 ft).
Friedmann died on September 16, 1925, at the age of 37, from typhoid fever that he contracted during a vacation in Crimea.
The moon crater Fridman is named after him.
Friedmann discovered the expanding-universe solution to the general relativity field equations in 1922, which was corroborated by Edwin Hubble's observations in 1929 (Ferguson 1991, p. 67). Friedmann's 1924 papers, including "Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes" (On the possibility of a world with constant negative curvature of space) published by the German physics journal Zeitschrift für Physik (Vol. 21, pp. 326–332), demonstrated that he had command of all three Friedmann models describing positive, zero and negative curvature respectively, a decade before Robertson and Walker published their analysis.
This dynamic cosmological model of general relativity would come to form the standard for the Big Bang and steady state theories. Friedmann's work supports both theories equally, so it was not until the detection of the cosmic microwave background radiation that the steady state theory was abandoned in favor of the current favorite Big Bang paradigm.
The classic solution of the Einstein field equations that describes a homogeneous and isotropic universe is called the Friedmann–Lemaître–Robertson–Walker metric, or FLRW, after Friedmann, and Howard Percy Robertson and Arthur Geoffrey Walker, and Georges Lemaître who worked on the problem in 1920's and 30's independently of Friedmann.
In addition to general relativity, Friedmann's interests included hydrodynamics and meteorology.
George Gamow and Vladimir Fock were among his students.