A separate article treats of Saint John Neumann, unrelated to this John von Neumann.

John von Neumann (December 28, 1903 - February 8, 1957) was a Hungarian-American mathematician who made important contributions in quantum physics, set theory, computer science, economics and virtually all mathematical fields.

The oldest of three children, von Neumann was born Neumann JŠnos in Budapest to Neumann Miksa (Max Neumann), a banker, and Kann Margit (Margaret Kann). Growing up in a non-practicing Jewish family, von Neumann, nicknamed "Jancsi", showed incredible memory at an early age, being able to divide eight-digit numbers in his head at the age of six. He entered the Lutheran Gymnasium in 1911. In 1913, his father purchased a title, and Neumann JŠnos acquired the German name von, becoming JŠnos von Neumann.

He received his Ph.D. in mathematics from the University of Budapest at the age of 23. Between 1926 and 1930 he was private lecturer in Berlin.

He was one of four people selected for first faculty of the Institute for Advanced Study. He worked on the Manhattan Project.

He was the father of game theory and published the classic book Theory of Games and Economic Behavior with Oskar Morgenstern in 1944. He conceived the concept of "MAD" (mutually assured destruction), which dominated American nuclear strategy in the Cold_War.

Von Neumann dashed all hope of developing a deterministic quantum mechanics until his work was overturned by David Bohm, J.S. Bell, and others. He held a strong belief in the role of the observer in creating the collapse of the quantum wave function.

Von Neumann devised the von Neumann architecture used in most non-parallel-processing computers. Virtually every commercially available home computer, microcomputer and supercomputer is a von Neumann machine. He created the field of cellular automata without computers, constructing the first examples of self-replicating automata with pencil and graph paper. The term von Neumann machine also refers to self-replicating machines. Von Neumann proved that the most effective way large-scale mining operations such as mining an entire moon or asteroid belt can be accomplished is through the use of self-replicating machines, to take advantage of the exponential growth of such mechanisms.

He also engaged in exploration of problems in these fields:

Von Neumann had a mind of great ingenuity and near total recall. He was an extrovert who loved drinking, dancing and having a good time. He had a fun-loving nature with a great love of jokes and humor. He died in Washington D.C.