  Exactly one hundred years ago, in May 1922, Alexander Friedmann discovered
that General Relativity (GR) predicts non-stationary Universe. His equation
describing the evolution of the Universe is now named after him. In this paper
we briefly recall the human and scientific aspects of this revolutionary change
in our picture of the world. We also recall that immediately after finishing
his seminal paper Friedmann wrote a book on GR for a wide audience. In that
book he presented an impressive picture of the expanding Universe created from
nothing.
