Born in Krzemieniec, Poland (now in Ukraine), I was the son of the first Jew from that city to receive an advanced university degree (and he got two of them).
Studying mathematics at the University of Lwow, I was inspired by the great Hugo Steinhaus, who challenged me to work on hard mathematical problems.
My focus was probability, and I eventually helped put it as a subject on a firm foundation.
In 1938, I assumed a postdoctoral fellowship at John Hopkins University...and it saved my life as my parents, brother, and almost all of my other relatives were killed during the Holocaust.
I remained in the U.S., teaching mathematics and doing research on probability theory at Cornell University, Rockefeller University, and USC.
A believer in the benefits of solving concrete applied problems, I always argued that mathematics "must never be separated from its roots in the real world."
My question, "Can one hear the shape of a drum?" led to considerable research into geometry and spectral theory...and the eventual answer was "no!"
Mark Kac (1914 - 1984)