John von Neumann
A Hungarian-American mathematician (1903–1957) who helped build the atomic age, designed the computer you are reading this on, and showed how a machine could copy itself.
A boy who did math in his head
Johnny von Neumann was born into a well-off banking family in Budapest. As a child, the stories go, he could divide eight-digit numbers in his head and recite pages of a phone book from memory. He earned a degree in chemical engineering in Zurich and, at the same time, a doctorate in mathematics in Budapest, both by age 23.
He came to America in 1930 to teach at Princeton, and in 1933 became one of the first professors at the new Institute for Advanced Study, alongside Albert Einstein. He became a U.S. citizen in 1937.
The atomic age
During World War II he joined the Manhattan Project at Los Alamos. He worked out the math of implosion: squeezing a ball of plutonium evenly with explosives so it would go critical. That was the design of the plutonium bomb. After the war he advised the government on nuclear weapons and served on the Atomic Energy Commission from 1955. In 1956 he received the Medal of Freedom and the first Enrico Fermi Award.
The computer
In 1945 he wrote a report on a new machine called EDVAC. In it he laid out a simple plan: keep the program and the data in the same memory, and have one processor fetch instructions one at a time. Engineers still call it the von Neumann architecture, and nearly every computer and phone uses it today. He went on to build his own computer at Princeton and used early computers for weather forecasting.
Game theory
With economist Oskar Morgenstern he wrote Theory of Games and Economic Behavior (1944), which founded game theory: the math of choices when other people are choosing too. It is still used in economics, business and military strategy.
The machine that copies itself
Starting with lectures in 1948, von Neumann asked a question nobody had answered: can a machine build a copy of itself? He showed that it can, if it has three parts:
Remarkably, he worked this out before scientists discovered the structure of DNA in 1953, and it is exactly how living cells copy themselves. He called the builder a universal constructor. His notes were finished by a colleague after his death and published in 1966 as Theory of Self-Reproducing Automata.
From machines to spaceships: the von Neumann probe
Later scientists put his idea on a spaceship. A von Neumann probe is a robot spacecraft that:
- flies to another planet, moon or asteroid,
- mines metal, ice and rock from it,
- builds copies of itself in a small factory,
- and launches those copies to the next worlds, where they do the same.
In 1980 engineer Robert Freitas published the first engineering study of such a probe. Scientists estimate that probes cruising at a tenth of the speed of light could spread across our whole Milky Way galaxy in about half a million years, a blink in the age of the galaxy.
Why he is in the news in 2026
On October 12, 2026, Microsoft's AI chief Mustafa Suleyman told an audience that Google co-founder Larry Page once told him he expected to be exploring the galaxy at the head of a von Neumann probe by the end of the century. On October 29, Elon Musk posted that exploring the galaxy with von Neumann probes by 2100 would be a great result for civilization. See how Musk's rockets and robots fit the idea.
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