Alan Turing

"Alan Turing was born exactly 100 years ago, [editor’s note: this interview was done in 2012] and died aged 41. In those 41 years he led an amazing life that is covered with extraordinary grace, complexity and completeness by Andrew Hodges in this biography. It was first published in 1983 and remains in print. No one could do a better job than Andrew Hodges, who is himself a mathematician – it is truly a masterpiece. Although it’s not a book about the history of computing per se , it’s a must read if you want to understand how we got to our modern world of computing, and gives you a great picture of the life and times of Alan Turing at this critical period. Turing was convicted of gross indecency in 1952 [for homosexual relations, then illegal in Britain] and sentenced to either imprisonment or oestrogen injections [to reduce libido]. He chose the oestrogen injections, which have an effect on personality and were a brutal treatment. He died in 1954 in what people assume was a suicide, although we don’t know for sure. This book is also very good on the details of what Alan Turing did, and what happened more generally, at Bletchley Park. Although when Hodges wrote the book, in 1983, much of the Bletchley Park material was still secret. During the Second World War, the Germans were using a machine called Enigma. The British, thanks to work by Turing and his innumerable colleagues, broke the Enigma cipher at Bletchley Park through a series of clever mathematical and human tricks. It’s unbelievable how much they did with so few computational resources, largely with human ingenuity. “It’s unbelievable how much they did with so few computational resources, largely with human ingenuity.” The Germans broke the rule of secrecy of not repeating yourself, and occasionally began messages with the same string of code. The other amazing thing is why this story was kept secret for so long, and not released after the war. It was one of the great achievements of the 20th century, and is finally out in the open. Yes. It was all happening during the war, but in secret. The group at Bletchley Park was moving very far ahead in code breaking. And in America [in the late 1940s] we had a computer called the ENIAC which made huge progress, but also in secret. After the war, the secrecy was lifted to some extent, so suddenly these developments that had been incubating came out into the open. I would be the first to say that Great Britain was ahead. In a way, the British invented digital computing and the Americans took the credit. Indeed! There’s a very direct connection. The push that allowed von Neumann build his universal machine was to solve hydrodynamic questions to decide whether a hydrogen bomb was possible or not. So to an extent it was a story of cryptography on the British side and nuclear weapons design on the American side, with of course some overlap."