Alan Turing
Alan Turing once chained his tea mug to a radiator at Bletchley Park, and cracked codes that shortened the Second World War. His story is odder, and sadder, than the legend.
Published
Quick Facts
- Born
- 23 June 1912, Maida Vale, London
- Died
- 7 June 1954, Wilmslow, Cheshire
- Known for
- Codebreaking at Bletchley Park and founding computer science
- Landmark paper
- "On Computable Numbers" (1936), which described the idea of the Turing machine
- Education
- Sherborne School, King's College Cambridge and Princeton University
- Honours
- OBE (1946) and Fellow of the Royal Society (1951)
- Posthumous recognition
- Royal pardon in 2013; appears on the Bank of England £50 note, issued 2021
- Hobby
- Serious long-distance running, with a marathon-standard personal best
The man who chained his mug to the radiator
Colleagues at Bletchley Park remembered Turing as brilliant and unmistakably odd. He kept his tea mug chained to a radiator pipe so nobody could borrow it. He sometimes cycled to work wearing a gas mask, which he said kept his hay fever at bay. There is another famous bicycle story: its chain kept slipping off at regular intervals. Rather than repair it, Turing counted the pedal turns and hopped off to fix it just before it failed. Born in Maida Vale in 1912, he was a boy who preferred experiments to Latin, a habit that did not always delight his teachers at Sherborne School.
The idea that became every computer
In May 1936, aged 23, Turing submitted a paper that asked what it really means to calculate something. His answer was an imaginary machine that reads and writes symbols on an endless tape, following simple rules. The Turing machine was never built as a gadget. It was a thought experiment, and it proved that a single machine could in principle carry out any calculation that can be described step by step. That is the seed of the modern programmable computer. The paper also showed that some questions can never be answered by any algorithm. Few people at the time realised how far those ideas would travel.
Hut 8 and the war against Enigma
When war came, Turing joined the Government Code and Cypher School at Bletchley Park in Buckinghamshire. He led work in Hut 8 on the German naval Enigma, the cipher that guided U-boats hunting Atlantic convoys. Building on Polish codebreaking work, he helped design the electromechanical Bombe, a machine that tested possible Enigma settings at speed. His methods let Bletchley read naval traffic that had been closed to the Allies. Secrecy meant the public knew nothing for decades. Bletchley's codebreakers were forbidden to speak of their work, so Turing never saw his wartime achievements celebrated in his lifetime.
Can machines think? He asked in 1950
After the war Turing worked on early computer designs, including the Automatic Computing Engine at the National Physical Laboratory, and later at the University of Manchester, where the Manchester computers were taking shape. In 1950 he published a paper asking whether machines can think, and proposed what we now call the Turing test: if a person chatting by text cannot tell a machine from a human, the machine has shown something like intelligence. Every debate about artificial intelligence still brushes against it. He then turned to biology. His 1952 paper on morphogenesis suggested that chemical reactions could produce patterns such as spots and stripes, an idea biologists still test today.
Prosecution, pardon and a belated thank you
In 1952 Turing was prosecuted for homosexual acts, which were then criminal in Britain. He accepted hormone treatment rather than prison. His security clearance was removed, ending his work with codebreaking agencies. He died at his home in Wilmslow in June 1954, aged 41. The inquest recorded suicide. In 2009 prime minister Gordon Brown issued a public apology on behalf of the British government. Turing received a royal pardon in 2013, and in 2017 the so-called Turing law pardoned many other men convicted under the same legislation.
Where you can still see his mark
Bletchley Park is now a museum where you can walk through the huts. The separate National Museum of Computing, on the same site, houses a working Bombe reconstruction. In Manchester, a statue of Turing sits on a bench in Sackville Gardens, near the Canal Street area. The city also has a bridge and a university building named in his honour. His face appears on the Bank of England £50 note, released in 2021, alongside a table of numbers and a mathematical formula. Computer science's top prize, the Turing Award, carries his name too.
Notable people
- Alan Turing
- Gordon Welchman
- Joan Clarke
- Marian Rejewski
- Max Newman
- Christopher Morcom
- Gordon Brown
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