## Friedmann, Aleksandr Aleksandrovich (1888–1925)Friedmann established an early reputation for his work on atmospheric and meteorological physics. However, he is best known for his 1922 paper on the expanding universe. This arose from work of Einstein in 1917 in which he attempted to apply his equations of general relativity to cosmology. Friedmann developed a theoretical model of the universe using Einstein's theory, in which the average mass density is constant and space has a constant curvature. Different cosmological models are possible depending on whether the curvature is zero, negative, or positive. Such models are called Friedmann universes.
## Related categories• PHYSICISTS• ASTRONOMERS AND ASTROPHYSICISTS • MATHEMATICIANS | ||||||

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