Mathematician and physicist remembered for his Friedmann equations, which sought to explain his theory of the universe's expansion.
After graduating from St. Petersburg State University, he fought for his native Russia in World War I.
He died of typhoid fever at the age of thirty-seven.
He was born in Saint Petersburg, Russia to a ballet dancer father (Alexander Friedmann) and a pianist mother (Ludmila Ignatievna Voyachek). He was married twice: to Ekaterina Dorofeyeva and, later, to Natalia Malinina.
He and astronomer Georges Lemaitre both theorized that the universe was expanding.