What Turing had already built

By 1950, Turing had already left his mark.

At Bletchley Park, during the Second World War, he became one of the central figures in breaking Enigma, work widely credited with giving the Allies a crucial advantage.

Before the war, he had imagined something stranger still: an abstract machine, now called the Turing machine, that could describe the limits of computation itself. It was only a thought experiment, but it became one of the great foundations of modern computing.

Turing wasn't just a dreamer. He built things, and insisted on understanding what he was building.