Mark Kac

Mark Kac (/kɑːts/ KAHTS; Polish: Marek Kac; 3 August 1914 – 26 October 1984) was a Polish American mathematician. He was born to a Polish-Jewish family; their town, Kremenets (Polish: "Krzemieniec"), changed hands from the Russian Empire to Poland when Kac was a child. His main interest was probability theory. His question, "Can one hear the shape of a drum?" set off research into spectral theory, with the idea of understanding the extent to which the spectrum allows one to read back the geometry. (In the end, the answer was "no", in general.)