Ninety years ago, in 1922, Alexander Friedman (1888-1925) demonstrated for\ud the first time that the General Relativity equations admit non-static solutions\ud and thus the Universe may expand, contract, collapse, and even be born. The\ud fundamental equations he derived still provide the basis for the current\ud cosmological theories of the Big Bang and the Accelerating Universe. Later, in\ud 1924, he was the first to realize that General Relativity allows the Universe\ud to be infinite. Friedman's ideas initially met strong resistance from Einstein,\ud yet from 1931 he became their staunchest supporter. This essay connects\ud Friedman's cosmological ideas with the 1998-2004 results of the astronomical\ud observations that led to the 2011 Nobel Prize in Physics. It also describes\ud Friedman's little known topological ideas of how to check General Relativity in\ud practice and compares his contributions to those of Georges Lemaitre. Recently\ud discovered corpus of Friedman's writings in the Ehrenfest Archives at Leiden\ud University sheds some new light on the circumstances surrounding his 1922 work\ud and his relations with Paul Ehrenfest
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