**Irving Segal** was an American mathematician known for work on theoretical quantum mechanics.

- Segal submitted his thesis Ring Properties of Certain Classes of Functions to Yale in 1940 and was awarded a Ph.D. in June of that year.
- During this latter period Segal worked as a researcher in the United States Army.
- This war work meant that Segal did not publish the detailed results of his thesis until 1947 when they appeared in the paper The group algebra of a locally compact group.
- One of Segal's main goals in the study of his group ring was to provide an appropriately general setting for the Wiener Tauberian theory, the theory of almost periodic functions, and harmonic analysis on locally compact groups.
- After the war ended in 1945, Segal was appointed as Oswald Veblen's assistant at the Institute for Advanced Study at Princeton.
- In 1957 Segal became a full professor at the University of Chicago and, three years later, he moved to the Massachusetts Institute of Technology where he was appointed as a Professor of Mathematics.
- During the winter of 1946-47 while at Princeton, Segal gave talks on his paper Postulates for general quantum mechanics.
- In fact, although Segal went on to contribute to several different areas of mathematics, all these had as their motivation the mathematical needs of quantum theory.
- Leonard Gross was one of Segal's Ph.D. students being awarded his doctorate in 1958.
- Although much of his work may seem to many mathematicians to be motivated simply by the usual aesthetic considerations - and is certainly justified by the intrinsic beauty of his ideas - Irving told me a few years ago that all of his work was aimed in one way or another at understanding quantum physics.
- Hence Segal's approach to M is quite unlike that of Einstein.
- Segal's theory, which is a variant of special relativity, is based on the idea that there are two kinds of time.
- Segal's theory is opposed to the big bang theory and Hubble's law for the expansion of the universe does not hold in Segal's theory.
- Segal continued to argue for his model of the universe after he retired as Professor of Mathematics at Massachusetts Institute of Technology in 1989.
- Segal's office was a cozy, lived-in place, cluttered with decades of accumulated papers.
- Everyone who knows Segal will recall his inability to do things any way other than his own.
- Let us look briefly at some of the books Segal published in addition to Mathematical Cosmology and Extragalactic Astronomy (1976) which we mentioned above.
- Finally we mention Introduction to algebraic and constructive quantum field theory (1992) which Segal wrote in collaboration with John Baez and Zheng-Fang Zhou.
- Segal received many honours for his contributions.

Born 13 September 1918, Bronx, New York, USA. Died 30 August 1998, Lexington, Middlesex, Massachusetts, USA.

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Astronomy, Origin Usa

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive