June 29, 1888|
|Died||September 16, 1925
|Fields||Mathematics and Physics|
|Institutions||Perm State University
Petrograd Polytechnical Institute
Main Geophysical Observatory
|Doctoral advisor||Vladimir Steklov|
|Doctoral students||George Gamow
|Known for||Friedmann equations
Alexander Alexandrovich Friedmann (also spelled Friedman or Fridman, Russian: Алекса́ндр Алекса́ндрович Фри́дман) (June 29 (17 old style) by himself, June 16 (4 old style) by J. O'Conor in 1888, Saint Petersburg, Russian Empire – September 16, 1925, Leningrad, USSR) was a Russian and Soviet physicist and mathematician. He is best known for his pioneering theory that the universe was expanding, governed by a set of equations he developed now known as the Friedmann equations.
Early life 
Alexander Friedmann was born to the composer and ballet dancer Alexander Friedmann (who was a son of a baptized Jewish cantonist) and the pianist Ludmila Ignatievna Voyachek. He lived much of his life in Saint Petersburg.
World War I 
During the war, he served in the Russian army as an aviator, an instructor and eventually, under the revolutionary regime, as the head of an airplane factory.
Friedmann became a professor at 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'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 both 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, Georges Lemaître, Howard Percy Robertson and Arthur Geoffrey Walker, who worked on the problem in 1920's and 30's independently of Friedmann.
Hydrodynamics and meteorology 
Personal life 
He married Natalia Malinina in the last years of his life. They had a religious wedding ceremony, though both were far from religious.
Named after Friedman 
The moon crater Fridman is named after him.
Selected publications 
- Friedman, A. (1922). "Über die Krümmung des Raumes". Zeitschrift für Physik 10 (1): 377–386. Bibcode:1922ZPhy...10..377F. doi:10.1007/BF01332580.. English translation in: Friedman, A. (1999). "On the curvature of space". General Relativity and Gravitation 31 (12): 1991–2000. Bibcode:1999GReGr..31.1991F. doi:10.1023/A:1026751225741. The original Russian manuscript of this paper is preserved in the Ehrenfest archive, together with some letters and unpublished work.
- Friedman, A. (1924). "Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes". Zeitschrift für Physik 21 (1): 326–332. Bibcode:1924ZPhy...21..326F. doi:10.1007/BF01328280.. English translation in: Friedmann, A. (1999). "On the Possibility of a World with Constant Negative Curvature of Space". General Relativity and Gravitation 31 (12): 2001–2008. Bibcode:1999GReGr..31.2001F. doi:10.1023/A:1026755309811.
- Hockey, Thomas (2009). The Biographical Encyclopedia of Astronomers. Springer Publishing. ISBN 978-0-387-31022-0. Retrieved August 22, 2012.
- Pyenson L. Book review. Physics Today [serial online]. September 1994; 47(9):93. Available from: MasterFILE Premier, Ipswich, MA. Accessed October 18, 2012.
- Pyenson L. Book review. Physics Today [serial online]. September 1994;47(9):93. Available from: MasterFILE Premier, Ipswich, MA. Accessed October 18, 2012.
- Daintith J. Dictionary Of Scientists [e-book]. Oxford University Press; 1999. Available from: eBook Collection (EBSCOhost), Ipswich, MA. Accessed October 18, 2012.
- "The final year". Alexander A Friedmann: The Man who Made the Universe Expand. Cambridge University Press. 2006. p. 209. ISBN 9780521025881. "[Alexander Friedmann and Natalia Malinina] even had a religious wedding ceremony in the Crimea, though both were far from religious. “Just to make it stronger,” Friedmann said to his wife (she told this to her sister Sofia)."
- Poluboyarinova-Kochina, P. Ya. (January–February 1964). "Aleksandr Fridman". Soviet Physics Uspekhi (English edition): 467–472.
- Ferguson, Kitty (1991). Stephen Hawking: Quest For A Theory of Everything. New York: Bantam Books. ISBN 0-553-29895-X.
- Frenkel', V.Ya. (1988). "Aleksandr Aleksandrovich Fridman (Friedmann): a biographical essay". Soviet Physics Uspekhi 31 (7): 645–665. Bibcode:1988SvPhU..31..645F. doi:10.1070/PU1988v031n07ABEH003574.
- Alexander A Friedmann: The Man who Made the Universe Expand - Biography written by Eduard A. Tropp, Viktor Ya. Frenkel and Artur D. Chernin
- O'Connor, John J.; Robertson, Edmund F., "Alexander Friedmann", MacTutor History of Mathematics archive, University of St Andrews.
- How Do We Know the Age of the Universe - Mary Lynn Germadnik