Alan Turing, 29 March 1951 © NPL Archive, Science Museum
Turing was amiable, athletic and open about his homosexuality, despite the repressive moral landscape of the 1950s. But he paid a high price for his candour and the manner of his passing was equally striking. Turing died of cyanide poisoning, aged only 41. The coroner's official verdict was suicide, although not everyone agrees.
This year, to mark the 100th anniversary of his birth on 23 June, 1912, Turing will be celebrated in works of fiction and art, in stamps and with a major biographical exhibition at the Science Museum in London, which examines his inspirational influence.
The exhibition’s curator, David Rooney, explained that: “Turing’s scientific creations and wartime heroics are beyond question but we are showing a more complete portrait of the man who, far from being the cold, insular lone genius of popular belief, was a convivial character with many endearing qualities.”
Here are some fascinating facets of Turing’s remarkable life:
Supreme code-breaker. During the Second World War, Turing was engaged in cracking the German enciphering machine, Enigma, and other cryptological challenges at Bletchley Park, the government's wartime communications headquarters. He took the lead in a team that designed a machine known as a ‘bombe’ that successfully decoded German messages. Eventually, over 200 were built, each weighing a ton. Turing became the chief scientific figure, nicknamed ‘Prof’, with a particular responsibility for reading U-boat communications. The breaking of the Enigma was vital, partly because it meant that the Allies could intercept messages to the U-boats that were attacking convoys, sinking merchant ships and threatening to isolate Britain altogether. It's even been claimed that the war might have been lost had not Turing outwitted Enigma.
Giant of computer science. After Turing was elected a Fellow of King's College, Cambridge University came his début in an area where he was an unknown figure: mathematical logic. This concept, also known as the ‘Turing machine’, is the basis for the modern theory of computation. His paper “On Computable Numbers...” gave a definition of computation and explored what it could achieve (automatic computation cannot solve all mathematical problems), which makes it the founding work of modern computer science.
Father of the computer. Combining his ideas from mathematical logic, his experience in cryptology, and his electronic knowledge, Turing’s ambition was to create a computer in the full modern sense. He joined the National Physical Laboratory in Teddington in 1945 where his detailed plan for an electronic computer, with a visionary prospectus, was accepted in March 1946 and led the world. But he laboured under the disadvantage that his remarkable wartime achievements were a state secret. Frustrated, Turing resigned in 1948 but eventually, in 1950, his ideas came to life at NPL in the form of the Pilot ACE computer, which forms the heart of the Science Museum’s Turing exhibition, the fastest at that time and the first capable of doing more than one thing at a time: the forerunner of today’s machines.
Athlete. Turing was a member of the Walton Athletic Club in Surrey, not far from the NPL. He was invited to join the amateur club after he was spotted running in the local area and a local remarked: "He made a terrible grunting noise when he was running, but before we could say anything to him, he was past us like a shot out of a gun." He would become their best runner. When asked why he trained so hard his frustration with the NPL became apparent: "I have such a stressful job that the only way I can get it out of my mind is by running hard." In a 1948 cross-country race he finished ahead of Tom Richards who was to win the silver medal in the 1948 Olympics. He almost qualified for the British team that same year.
Pioneer of artificial intelligence. Turing soon returned to the theoretical limitations of computation, contrasting the power of the human brain. On Midsummer Day 1948, the first prototype general-purpose computer, a true Universal Turing Machine, was working at Manchester. At Manchester University, Turing was Deputy Director of the computing laboratory and wrote his highly influential 1950 paper, 'Computing Machinery and Intelligence'. How could the intelligent arise from operations which were themselves routine and in a sense mindless, or ‘entirely without intelligence’? In the paper he came up with the Turing Test: if a computer could fool a person into thinking that he were interacting with another person, rather than a machine, then it could be classified as having artificial intelligence. As part of the 2012 celebrations Bletchley Park Museum will host the annual competition, known as the Loebner Prize, to find the world’s best conversational computer program.
Nature's patterns. In 1951 Turing was elected a Fellow of the Royal Society, the national academy of science, as he struck out into new territory. He became interested in furnishing a chemical basis for the means by which shape, structure and function arise in living things. It is known in biology as morphogenesis. Turing asked himself a simple question. How does an organism marshal a chemical soup into a biological structure or turn a spherical (symmetrical) bundle of identical cells into an (asymmetrical) organism? And why are there Fibonacci numbers (where each number is the sum of the previous two) in the leaf patterns of plants such as the close-packed spirals of sunflower heads and fir cones. Turing's ideas have led to some impressive descriptions of pattern formation in Nature, from snail shells to snake skins.
Gay before his time. Turing was still at the University of Manchester when he was arrested in February 1952 for his sexual affair with a young man, and tried for homosexuality, then a criminal offence. Turing was convicted of “gross indecency” and, to avoid prison, accepted treatment with the female sex hormone oestrogen: ‘chemical castration’ intended to neutralise his libido. In that era, homosexuals were considered a security risk as they were open to blackmail. Turing's security clearance was withdrawn, so that he could no longer work for GCHQ, the post-war successor to Bletchley Park. (In 2009 Gordon Brown, the then Prime Minister, issued a public apology and stated: "It is no exaggeration to say that, without his outstanding contribution, the history of the Second World War could have been very different.")
Death. On a Whit Monday in Wilmslow, Cheshire, the coldest and wettest for 50 years, Turing died at home of cyanide poisoning. The circumstances surrounding his demise on 7 June, 1954 are sufficiently murky that some suggest that assassination should not be ruled out. But Turing had himself spoken of suicide, and perhaps he wanted those who wished to do so to believe his death was the result of his penchant for chemistry experiments.
Next to his body was an apple, partly eaten (it was not tested for cyanide). Years before, Turing had gone to see Snow White and the Seven Dwarfs in Cambridge and was particularly taken with the scene where the Wicked Witch dangled an apple into a boiling cauldron of poison, muttering: "Dip the apple in the brew. Let the Sleeping Death seep through.” One biographer, David Leavitt, put it this way: Turing decided "to camp it up a bit - to invest his departure from a world that had treated him shabbily with some of the gothic, eerie, colourful brilliance of a Disney film."
Today, a statue of Turing can be found in the Sackville Park in Manchester. He sits there on a bench - on his left is the university and on his right is the city’s gay village. A plaque at Turing’s feet says: "Father of computer science, mathematician, logician, wartime codebreaker, victim of prejudice".
Roger Highfield is the director of external affairs at the National Museum of Science and Industry. Codebreaker – Alan Turing’s life and legacy opens at the Science Museum on June 21, 2012, for more info visit www.sciencemuseum.org.uk