Mathematician and Polymath.

John von Neumann (December 28, 1903 – February 8, 1957) was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including mathematics (set theory, functional analysis, ergodic theory, geometry, numerical analysis, and many other mathematical fields), physics (quantum mechanics, hydrodynamics, and fluid dynamics), economics (game theory), computer science (linear programming, computer architecture, self-replicating machines, stochastic computing), and statistics. He is generally regarded as one of the greatest mathematicians in modern history.

The mathematician Jean Dieudonné called von Neumann "the last of the great mathematicians", while Peter Lax described him as possessing the most "fearsome technical prowess" and "scintillating intellect" of the century, and Hans Bethe stated "I have sometimes wondered whether a brain like von Neumann's does not indicate a species superior to that of man". He was born in Budapest around the same time as Theodore von Kármán (b. 1881), George de Hevesy (b. 1885), Leó Szilárd (b. 1898), Eugene Wigner (b. 1902), Edward Teller (b. 1908), and Paul Erdős (b. 1913).

Von Neumann was a pioneer of the application of operator theory to quantum mechanics, in the development of functional analysis, a principal member of the Manhattan Project and the Institute for Advanced Study in Princeton (as one of the few originally appointed), and a key figure in the development of game theory and the concepts of cellular automata, the universal constructor, and the digital computer. Von Neumann's mathematical analysis of the structure of self-replication preceded the discovery of the structure of DNA. In a short list of facts about his life he submitted to the National Academy of Sciences, he stated "The part of my work I consider most essential is that on quantum mechanics, which developed in Göttingen in 1926, and subsequently in Berlin in 1927–1929. Also, my work on various forms of operator theory, Berlin 1930 and Princeton 1935–1939; on the ergodic theorem, Princeton, 1931–1932." Along with Teller and Stanisław Ulam, von Neumann worked out key steps in the nuclear physics involved in thermonuclear reactions and the hydrogen bomb.

Von Neumann's ability to instantaneously perform complex operations in his head stunned other mathematicians. Eugene Wigner wrote that, seeing von Neumann's mind at work, "one had the impression of a perfect instrument whose gears were machined to mesh accurately to a thousandth of an inch." Paul Halmos states that "von Neumann's speed was awe-inspiring." Israel Halperin said: "Keeping up with him was... impossible. The feeling was you were on a tricycle chasing a racing car."[Edward Teller wrote that von Neumann effortlessly outdid anybody he ever met, and said "I never could keep up with him". Lothar Wolfgang Nordheim described von Neumann as the "fastest mind I ever met", and Jacob Bronowski wrote "He was the cleverest man I ever knew, without exception. He was a genius." George Pólya, whose lectures at ETH Zurich von Neumann attended as a student, said "Johnny was the only student I was ever afraid of. If in the course of a lecture I stated an unsolved problem. He'd come to me at the end of the lecture with the complete solution scribbled on a slip of paper."

In 1955, von Neumann was diagnosed with what was either bone or pancreatic cancer. While at Walter Reed, he invited a Roman Catholic priest, Father Anselm Strittmatter, O.S.B., to visit him for consultation. Von Neumann is reported to have said in explanation that Pascal had a point, referring to Pascal's wager. He is said to have been an 'agnostic Catholic' due to his agreement with Pascal's wager. Father Strittmatter administered the last sacraments to him. Some of Von Neumann's friends believed that his religious conversion was not genuine since it did not reflect his attitudes and thoughts when he was healthy. Even after his conversion, Strittmatter recalled that Von Neumann did not receive much peace or comfort from it as he still remained terrified of death.

Sources:

1.) Norman MacRae (1992). John Von Neumann: The Scientific Genius Who Pioneered the Modern Computer, Game Theory, Nuclear Deterrence, and Much More (2 ed.). American Mathematical Soc.. p. 379. ISBN 9780821826768. "But Johnny had earlier said to his mother, "There probably is a God. Many things are easier to explain if there is than if there isn't." He also admitted jovially to Pascal's point: so long as there is the possibility of eternal damnation for nonbelievers it is more logical to be a believer at the end."

2.) William Poundstone (1993). Prisoner's Dilemma. Random House Digital, Inc.. ISBN 9780385415804. "Of this deathbed conversion, Morgenstern told Heims, “He was of course completely agnostic all his life, and then he suddenly turned Catholic—it doesn't agree with anything whatsoever in his attitude, outlook and thinking when he was healthy.” The conversion did not give von Neumann much peace. Until the end he remained terrified of death, Strittmatter recalled."

3.) Abraham Pais (2006). J. Robert Oppenheimer: A Life. Oxford University Press. p. 109. ISBN 9780195166736. "He had been completely agnostic for as long as I had known him. As far as I could see this act did not agree with the attitudes and thoughts he had harbored for nearly all his life. On February 8, 1957, Johnny died in the Hospital, at age 53."

4.) Key Ideas in Economics. Nelson Thornes. 2003. p. 124. ISBN 9780748770816. "He was brought up in a Hungary in which anti-Semitism was commonplace, but the family were not overly religious, and for most of his adult years von Neumann held agnostic beliefs."