[1] Leopold Infeld was born into a family of Polish Jews in Kraków, then part of the Austro-Hungarian Empire (it rejoined an independent Poland in 1918).

The two scientists jointly formulated the equation describing star movements as well as concurrently writing the book The Evolution of Physics.

In the US, despite having worked previously directly with Einstein, who formally invented nuclear weapons with his famous formula, Infeld risked receiving the death penalty like the Rosenbergs if accused of spying for the Soviet Union.

In the staunchly anti-communist climate of the time, many in the Canadian government and media feared that working in a communist country he would betray nuclear weapons secrets.

Infeld is the author of Quest: An Autobiography and the biography Whom the Gods Love: The Story of Évariste Galois.

In New Jersey, on April 12, 1939, he married a mathematician who took the name Helen Infeld and they had two children, both born in Toronto, Joan M. and Eric (sometimes spelled Eryk).