Stanisław Ulam filled a café notebook with problems, then invented the Monte Carlo method
In 1930s Lwów, mathematicians argued for hours at the Scottish Café and wrote their unsolved puzzles in a thick notebook supplied by Stefan Banach's wife. Stanisław Ulam contributed more problems than almost anyone. A decade later, in New Mexico, he found a way to let computers attack problems no formula could crack.
Ulam was born in 1909 in Lemberg, then in Austria-Hungary and later the Polish city of Lwów, into a well-off Jewish family; his father was a lawyer. He published his first paper at 20 and earned his doctorate in 1933 under Kazimierz Kuratowski. As a member of the Lwów School of Mathematics founded by Banach and Hugo Steinhaus, he wrote 40 of the 193 problems in the Scottish Book on his own and shared many more. Steinhaus later sent him the book, which had survived the war, and Ulam translated it into English.
John von Neumann invited him to Princeton in 1935, and from 1936 he spent academic years at Harvard. On 20 August 1939 his father put Stanisław and his younger brother Adam on a ship to America from Gdynia; eleven days later Germany invaded Poland. His father, his sister and much of the family were killed in the Holocaust. Ulam became a United States citizen in 1941 while teaching in Wisconsin.
In 1943 Hans Bethe invited him to a secret project near Santa Fe; checking out a guidebook to New Mexico, Ulam found the names of Wisconsin colleagues who had mysteriously vanished. At Los Alamos he did calculations for the implosion design and joked that he, a pure mathematician, had sunk so low his latest paper contained decimal points. After the war he showed Edward Teller's original hydrogen bomb design would not work, and in 1951 the two produced the Teller–Ulam design.
His best-known legacy is peaceful: he realised that electronic computers made it practical to estimate answers by running huge numbers of random trials, the Monte Carlo method now standard across science. He also recognised the concept of the cellular automaton, co-studied the Fermi–Pasta–Ulam–Tsingou problem that sparked nonlinear science, and proposed propelling spacecraft with small nuclear blasts, which became Project Orion. He died in 1984.
Source: Stanisław Ulam
