[2] Friedmann fought in World War I on behalf of Imperial Russia, as an army aviator, an instructor, and eventually, under the revolutionary regime, as the head of an airplane factory.

Unaware of Friedmann's work, in 1927 Belgian astronomer Georges Lemaître independently formulated an evolving Universe.

[5] Friedmann's 1924 papers, including "Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes" ("On the possibility of a world with constant negative curvature of space") published by the German physics journal Zeitschrift für Physik (Vol.

326–332), demonstrated that he had command of all three Friedmann models describing positive, zero and negative curvature respectively, a decade before Robertson and Walker published their analysis.

[citation needed] This dynamic cosmological model of general relativity would come to form the standard for both the Big Bang and Steady State theories.

He had allegedly contracted the bacteria on return from his honeymoon in Crimea, when he ate an unwashed pear bought at a railway station.