## John von Neumann

**Article abstract:** A brilliant mathematician who laid the mathematical foundations of modern physics and computer science, von Neumann affirmed the importance of autonomous scientific research during the anti-Communist McCarthy era.

**Early Life**

The eldest of three boys, John von Neumann was born in Budapest on December 28, 1903. In the United States, he came to be known universally as Johnny, perhaps because he was already known by the Hungarian Jancsi. Von Neumann belonged to the group of Hungarian mathematicians and physicists including Eugene Wigner, Edward Teller, Leo Szilard, and Dennis Gabor, who have substantially contributed to twentieth century science. In addition to knowing one another, some of them even attended the same high school, Budapest Lutheran.

Von Neumann’s father, Max von Neumann, was a successful banker who had been elevated to the nobility. The Hungarian honorific “Margittai” was later Germanized to “von.” The family was Jewish and bilingual in Hungarian and German. When John entered the gymnasium at age ten, he came into contact with Lászlo Rátz, a teacher who perceived his mathematical talents and arranged with his father for special tutoring. Von Neumann worked concurrently on a degree in chemical engineering, awarded by the Eidgenössische Technische Hochschule of Zurich in 1926, and a doctorate in mathematics, which was awarded by the University of Budapest, also in 1926.

Although von Neumann then held positions at the University of Berlin and at the University of Hamburg, he also visited Göttingen, where there was an amazing group of physicists and mathematicians, including David Hilbert, Werner Heisenberg, Max Born, and Erwin Schrödinger. The visitors included Albert Einstein, Wolfgang Pauli, Linus Pauling, J. Robert Oppenheimer, and Norbert Wiener.

After coming to the United States as a visiting professor at Princeton University in 1930, he accepted a permanent position in 1931. In 1933, he was invited to join the permanent faculty of the Institute for Advanced Study, also located at Princeton University, and became the youngest faculty member at the institute. He married Marietta Kövesi in 1930; she was Catholic, and he at least nominally became a Catholic during his first marriage. His daughter, Marina, was born in Princeton in 1935. The marriage ended in divorce in 1937. In 1938, he visited Hungary and married Klára Dán, who joined him in Princeton.

Von Neumann was one of the rare men of extraordinary scientific genius who was as engaging personally as he was brilliant mentally. Colleagues relate anecdotes concerning his foibles, but all with a touch of nostalgia because his charm as well as his intelligence endeared him to those who knew him best. Von Neumann was of medium size, slender as a young man, plump as he grew older. His colleagues teased him about dressing like a banker—perhaps because he was the son of a banker; he habitually wore three-piece suits with a neatly buttoned coat and a handkerchief in his pocket. Cheerful and gregarious, he was a great raconteur. Not at all athletic, he had to watch his appetite for rich gravies, sauces, and desserts. He drove erratically, regularly acquiring speeding tickets and wearing out approximately a car a year. According to his friends, he was not mechanical enough to change a tire on his car, but his wife attributed to him a great skill at releasing zippers.

Because of his powers of concentration, he could appear absentminded. He would sometimes start out on a trip and then have to call home to find out with whom he had an appointment and where it was to be. He loved off-color limericks and repeated them at parties. Especially fond of children, he enjoyed their toys so much that friends would give him toys as gifts on special occasions. Von Neumann’s associates described him as sociable, witty, and party-loving.

History intrigued von Neumann. He had systematically read and learned most of the names and facts in the twenty-one volumes of the *Cambridge Ancient History* (1923-1939). During World War II, his colleagues were amazed at how frequently his forecasts were borne out by later events. Once asked by his colleague Herman Goldstine to recite Charles Dickens’ *A Tale of Two Cities* (1859), von Neumann continued for so long that it was clear that he was prepared to recite from memory the entire book, even though he had read it twenty years before. While he had a photographic memory of books he had read decades earlier, he was quite capable of forgetting what his luncheon menu had been. When his wife once asked him to get her a glass of water, he came back and asked her where the glasses were—even though they had lived in the same house for seventeen years.

**Life’s Work**

Von Neumann’s first group of mathematical papers involved presenting an axiomatic treatment of set theory. Related to this concern with set theory was the problem of the freedom of contradiction of mathematics. Bertrand Russell and Alfred North Whitehead, in *Principia Mathematica* (1910-1913), contended that all mathematics derives from logic and is without contradiction. In 1927, following David Hilbert, who wanted to separate number from experiential logic, where seven is related to seven objects, von Neumann argued that all analysis could be proved to be without contradiction. Three years later, the German mathematician Kurt Gödel upset these theories by showing that “in any sufficiently powerful logical system, statements can be formulated which are neither provable nor unprovable within that system unless the system is logically inconsistent.” Von Neumann was entirely comfortable with theoretical issues of this kind.

In a series of important papers, culminating in his book entitled *The Mathematical Foundations of Quantum Mechanics* (1944), von Neumann...

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