Stanisław Marcin Ulam (April 13, 1909–May 13, 1984) was a Polish-American mathematician who helped develop the key theory behind the hydrogen bomb.

Biography

Ulam was born in Lwów, Poland (then also called Lemberg and part of Galicja, an autonomous province of Austria-Hungary, now L'viv, Ukraine). His master in mathematics was Stefan Banach, a great Polish mathematician, one of the moving spirits of the Lwów School of Mathematics.

Ulam went to the US in 1938 as a Harvard Junior Fellow. When his fellowship was not renewed, he served on the faculty at the University of Wisconsin, and supported his brother, Adam, who had fled from Poland on the eve of World War. While there, in the midst of World War II, his friend John von Neumann invited him to a secret project in New Mexico. To research the invitation, Ulam checked out a book on New Mexico from the University Library, and found, listed on the library check-out card, those who had successively disappeared from the campus at the UW. Ulam then joined the Manhattan Project at Los Alamos.

While there, he suggested the Monte Carlo Method for evaluating complicated mathematical integrals that arise in the theory of nuclear chain reactions (not knowing that Fermi and others had used the method earlier). This suggestion led to the development of Monte Carlo by Von Neumann, Metropolis, and others.

Ulam—in collaboration with C. J. Everett, who did the detailed calculations—showed Edward Teller's early model of the hydrogen bomb to be inadequate. Ulam then went on to suggest a better method himself. He was the first one to realize that one could put all of the H-bomb's components inside one casing, put a fission bomb at one end and thermonuclear material at the other, and use shock waves from the fission bomb to compress and detonate fusion fuel.

Teller resisted this idea at first, then saw its merit and suggested the use of radiation rather than shock waves. "Radiation implosion", as the method came to be called, has been the standard method of creating H-bombs ever since. Ulam and Teller jointly applied for a patent on the hydrogen bomb.

Ulam also invented nuclear pulse propulsion, and at the end of his life, declared it the invention of which he was most proud.

He was an early proponent of the use of computers to perform "mathematical experiments". His most notable contribution in this area may have been his part in the Fermi-Pasta-Ulam experiments, an early numerical study of a dynamical system.

In pure mathematics, he worked in set theory (including measurable cardinals and abstract measures), topology, ergodic theory, and other fields. After World War II he largely turned from rigorous pure mathematics to speculative and imaginative work, posing problems and making conjectures (which had always been specialties of his) that often concerned the application of mathematics to physics and biology. His friend Gian-Carlo Rota ascribed this change to an attack of encephalitis in 1946 that Rota claimed changed Ulam's personality (though detail had never been Ulam's strong point). This suggestion is believed by many but rejected by Ulam's widow, Françoise, among others.

Ulam took a position at the University of Colorado in 1965. As he remained a consultant at Los Alamos, he divided his time between Boulder, Colorado, USA and Santa Fe, New Mexico, from which he commuted to Los Alamos. Later he and his wife spent winters in Gainesville, Florida, where he had a position with the University of Florida. He died in Santa Fe.

Books

• Stanislaw Ulam, The Scottish Book: A Collection of Problems, Los Alamos 1957
• Stanislaw Ulam, A Collection of Mathematical Problems, Interscience Publishers, New York (1960)
• Mark Kac and Stanislaw Ulam: Mathematics and Logic: Retrospect and Prospects, Praeger, New York (1968)
• Stanislaw Ulam, Sets, Numbers and Universes, Cambridge, Massachusetts 1974
• Stanislaw Ulam, Adventures of a Mathematician, Charles Scribner's Sons, New York (1983), his autobiography

See also

• Borsuk-Ulam Theorem
• Lucky number (1955)
• Ulam spiral (1963)
• Scottish Café

External Links

Ulam biography (http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Ulam.html) from the MacTutor history of mathematics (http://www-gap.dcs.st-and.ac.uk/~history/).

Further Reading

Necia Grant Cooper, Roger Eckhardt, Nancy Shera, editors, From Cardinals to Chaos, Cambridge University Press (1989). Reminiscences by people close to Ulam, memorial articles on aspects of his work, and previously unpublished informal work by him.