Computer scientist, mathematician, logician, cryptanalyst and theoretical biologist; quite a list of credentials finds itself attached to the polymath Alan Turing. His work changed the course of not only the Second World War but of the world — and Turing also stands as a stark reminder of a time hostile to difference.
Turing’s name is embedded in popular culture. His life has been celebrated through numerous films and books and since 2014’s The Imitation Game, where he was played by the ever popular Benedict Cumberbatch, his story is more widely known than ever — including his treatment as a gay man in mid-20th century Britain. Turing was sentenced to chemical castration in 1952 for ‘gross indecency by engaging in homosexual acts’. Gordon Brown's 2009 apology for his treatment brought him to yet wider attention, and today Turing is remembered not only for the astounding impact of his pioneering work, but as a reminder of the cruelty and senselessness of discrimination.
Turing’s work
The concept of Turing Machines and the Turing test lie in his most famous paper, On Computable Numbers, with an Application to the Entscheidungsproblem, published in 1936. This paper was highly influential in the development of theoretical computer science, providing a formalisation of the concepts of the algorithm and computation with the Turing machine, which can be considered a model of a general purpose computer.
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Famously, some of his ideas were given practical application. During the Second World War, the Germans thought that they had unbreakable ciphers produced by their Enigma machines. Alan Turing’s pioneering work refining the design of the polish device ‘bomba’ into the Bombe, an electro-mechanical cryptographic computer, definitively cracked the code. The first British Bombe, codenamed Victory, was in use by March 1940.
Bletchley Park's cryptographers were able to decode over 3,000 enemy messages a day and turn the course of the war, providing intelligence on German troop movements and military strategy critical to the Allied war effort; many experts believe that cracking the Enigma code could have shortened the war by several years. Amongst other critical points, the intelligence provided by Turing’s machine was indispensable to the success of the D-Day landings, the 80th anniversary of which we celebrate this year.
Turing as a gay man
In 1952, Turing was burgled by a man known to his then lover, Andrew Murray; on reporting the crime, Turing acknowledged having a sexual relationship with Murray and both men were charged with ‘gross indecency’. Given the choice of imprisonment or probation conditional on undergoing chemical castration, Turing chose the latter — imprisonment would have resulted in his losing his post at Manchester University which gave him access to one of the world’s only computers. Some of the side effects of chemical castration included impotence and physical changes.
Turing died as a result of cyanide poisoning in 1954. Though it is now unclear whether he committed suicide or whether his death was accidental, what we do know is that he was an eccentric, passionate, and exceptional man with a formidable mind. Homosexuality was officially decriminalised in 1967, and Alan Turing was posthumously pardoned in 2013.
Find out more about Turing
- From cryptanalysis to cognitive neuroscience - a hidden legacy of Alan Turing, Professor Ray Dolan, 2012 – from The Turing Lecture Series, part of the IET Prestige Lecture Series
- A biography of Alan Turing – Encyclopaedia Britannica
- Alan Turing: British mathematician, logician, cryptanalyst and computer scientist, Institute of Engineering and Technology
- The Turing Scheme
