Alan Turing, the great British mathematician who cracked Nazi codes, set the stage for our digital age and later killed himself after the government chemically castrated him for being gay, received a posthumous royal pardon last week, 61 years after his conviction on the "gross indecency" laws of the time. 

Turing's life will soon be the basis for the film The Imitation Game, starring Benedict Cumberbatch. Last year I spoke with technology historian George Dyson about his book Turing's Cathedral: The Origins of the Digital Universe.

My conversation with George Dyson: