Alexander Friedman
Alexander Friedmans
Born	June 16, 1888(1888-06-16) Saint Petersburg
Died	September 16, 1925 (aged 37) Leningrad
Nationality	Russia
Fields	cosmologist
Doctoral students	George Gamow

Alexander Alexandrovich Friedman or Friedmann (Russian: Александр Александрович Фридман) (June 16, 1888, Saint Petersburg, Imperial Russia – September 16, 1925, Leningrad, USSR) was a Russian and Soviet cosmologist and mathematician.

Contents 1 Life and work 2 See also 3 Important works 4 References 5 External links

[edit] Life and work

Alexander Friedman lived much of his life in Leningrad. He fought in World War I (on behalf of Imperial Russia) as a bomber and later lived through the Russian Revolution of 1917.

Friedman 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.

He 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: 67). Friedman'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 Friedman 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. Friedman'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 Friedman, and Robertson, Walker and Georges Lemaître who worked on the problem in 1920's and 30's independently of Friedman.

In addition to general relativity, Friedman's interests included hydrodynamics and meteorology. 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 (24,000 ft).

Friedman died on September 16, 1925, at the age of 37, from typhoid fever that he contracted during a vacation in Crimea.

Another famous physicist, George Gamow, was a student of Friedman.

[edit] See also

• Big Bang nucleosynthesis
• infinity
• energy
• conservation of energy
• Friedmann equations

[edit] Important works

• Friedman, A. (1922). "Über die Krümmung des Raumes". Zeitschrift für Physik 10 (1): 377–386. doi:10.1007/BF01332580. 
• English translation in: Friedman, A. (1999). "On the curvature of space". General Relativity and Gravitation 31: 1991–2000. doi:10.1023/A:1026751225741.  edit
• Friedman, A. (1924). "Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes". Zeitschrift für Physik 21 (1): 326–332. 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: 2001–2008. doi:10.1023/A:1026755309811.  edit

[edit] References

• Poluboyarinova-Kochina, P. Ya. (January-February 1964). "Aleksandr Fridman". Soviet Physics Uspekhi (English edition): 467–472. http://www.iop.org/EJ/article/0038-5670/6/4/E01/PHU_6_4_E01.pdf?request-id=7429cf76-2dd8-4055-87c8-fa001c02acd1. 
• Ferguson, Kitty (1991). Stephen Hawking: Quest For A Theory of Everything. New York: Bantam Books. ISBN 055329895X. 

[edit] External links

• O'Connor, John J.; Robertson, Edmund F., "Alexander Friedmann", MacTutor History of Mathematics archive, http://www-history.mcs.st-andrews.ac.uk/Biographies/Friedmann.html .
• How Do We Know the Age of the Universe - Mary Lynn Germadnik