Alexander Alexandrovich Friedmann (29.06.1888 —16.09.1925) was a Soviet physicist and mathematician. He was born in St Petersburg. He graduated from St Petersburg University (1910) and was kept on there to prepare for a professorship. From 1920 he was a professor at Petrograd University. Shortly before his death he became director of the Main Geophysical Observatory.
His main work was in the field of the mechanics of a compressible fluid, the theory of turbulence, dynamic meteorology, atmospheric physics and relativistic cosmology. In the book “Essay on the Hydromechanics of a Compressible Fluid” (1922) he laid the foundations of theoretical meteorology. He obtained important results on the general problem of turbulence. In particular, in 1924 he proposed, together with L. V. Keller, a general method of describing the structure of turbulence. Together with V. K. Frederiks he was the first to introduce Russian physicists to the general theory of relativity. In 1922 — 23, in the papers “On the Curvature of Space” and “On the Possibility of a World with a Constant Negative Curvature of Space”, he found non-stationary solutions of Einstein's gravitational equation, proving the possibility of a non-stationary (expanding) Universe. This result became the basis of modern cosmology. In 1929 his theory was confirmed by the discovery of the recession of the galaxies.
V. I. Lenin Prize (1931, posthumous). Under Friedmann's influence I. E. Kochin, G. A. Grinberg, B. I. Izvekov, I. A. Kibel, L. G. Loitsyansky, A. I. Lurie, P. Ya. Polubarinova-Kochina and others developed as scientists. The Presidium of the USSR Academy of Sciences established the A. A. Friedmann Prize.