Russian mathematician and physical scientist.

After graduating from the University of St. Petersburg in 1910, Friedmann joined the Pavlovsk Aerological Observatory and, during World War I, did aerological work for the Russian army. After the war he was on the staff of the University of Perm (1918–20) and then on the staffs of the Main Physical Observatory and other institutions until his death in 1925.

Friedmann was first to formulate (1922) the mathematics of a model universe in which the average mass density is constant and all fundamental parameters are known except the expansion factor, or radius of curvature. His model has been of great significance in the mathematical derivation of cosmological models from Albert Einstein's general theory of relativity. Friedmann was also one of the first to postulate (1922, 1924) a “big bang” model for the evolution of the universe. He was also a founder of the science of dynamic meteorology.