Stanisław Marcin Ulam

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Stanisław Marcin Ulam (April 13, 1909–May 13, 1984) was a Polish mathematician who helped develop the Teller-Ulam design which powers the hydrogen bomb, as well as a number of other important mathematical tools.

Contents 1 Biography 2 Books 3 See also 4 Bethe's denotation of Ulam 5 External links 6 Further reading

Biography

Stanisław Ulam was born in Lviv (German Lemberg, Polish Lwów) Galicja, Austria-Hungary (now Ukraine). He was part of the city's Polish majority. His mentor 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 the Second World War. While there, in the midst of the war, his friend John von Neumann invited him to a secret project in New Mexico. Ulam researched the invitation by checking out a book on New Mexico from the university library. There he found a list, on the library check-out card, of all 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 a similar method earlier). This suggestion led to the more systematic 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 X-ray radiation 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 a Plutonium "spark plug", located at the center of the fusion fuel, to initiate and enhance the fusion reaction. This design, generally referred to as staged radiation implosion, has been the standard method of creating H-bombs ever since. Although this approach was worked out independently by Soviet physicist Andrei Sakharov, it is often refered to as the "Teller-Ulam design". 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.

In May 1958, while referring to a conversation with von Neumann, Ulam said what would later became a foundation of the technological singularity theory: "One conversation centered on the ever accelerating progress of technology and changes in the mode of human life, which gives the appearance of approaching some essential singularity in the history of the race beyond which human affairs, as we know them, could not continue."

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 on May 13, 1984.

Books

• Stanisław Ulam, The Scottish Book: A Collection of Problems, Los Alamos 1957
• Stanisław Ulam, A Collection of Mathematical Problems, Interscience Publishers, New York (1960)
• Mark Kac and Stanisław Ulam: Mathematics and Logic: Retrospect and Prospects, Praeger, New York (1968)
• Stanisław Ulam, Sets, Numbers and Universes, Cambridge, Massachusetts 1974
• Stanisław 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

Bethe's denotation of Ulam

• "After the H-bomb was made, reporters started to call Teller the father of the H-bomb. For the sake of history, I think it is more precise to say that Ulam is the father, because he provided the seed, and Teller is the mother, because he remained with the child. As for me, I guess I am the midwife." - 1968 (Hans Bethe, as quoted by Schweber, p.166)

External links

Biography at the MacTutor archive

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.