John von Neumann (1903–1957) was, by the account of nearly everyone who met him, the fastest mind of the 20th century — a Hungarian prodigy who could divide eight-digit numbers in his head at six, joke in classical Greek, and reshape half a dozen fields before lunch. Colleagues at Princeton, surrounded by geniuses including Einstein, quietly agreed that von Neumann was on another level entirely.

The blueprint of every computer

In 1945 he wrote down the design that essentially every computer still follows: a single memory that holds both the data and the program, with a processor that fetches and executes instructions one after another. That von Neumann architecture is why your laptop, phone and games console all work the same way under the hood. Along the way he also invented merge sort, co-founded game theory, worked on the atom bomb, and laid mathematical foundations for quantum mechanics — any one of which would headline a normal career.

The fly, the two trains, and an infinite series