|Friedman, Aleksandr Aleksandrovich (1888-1925)|
Russian mathematician and cosmologist, who made fundamental contributions
to the development of theories regarding the expansion of the universe.
Friedman was born and educated in St Petersburg, where he joined the mathematics faculty. From 1918 to 1920 he was professor of theoretical mechanics at Perm University, but he returned to St Petersburg in 1920 to conduct research at the Academy of Sciences.
Friedman's early research was in the fields of geomagnetism, hydromechanics. and, above all, theoretical meteorology. His work of the greatest relevance to astronomy was his independent and original approach to the solution of Albert Einstein's field equation in the general theory of relativity. Einstein had produced a static solution, which indicated a closed universe. Friedman derived several solutions, all of which suggested that space and time were isotropic (uniform at all points and in every direction), but that the mean density and radius of the universe varied with time - indicating an either expanding or contracting universe.