Alan Turing

Lore & Background

Turing was born in Maida Vale, London, while his father was on leave from the Indian Civil Service. He was raised in southern England and attended Sherborne School, where he formed a significant friendship with Christopher Collan Morcom, described as his first love. Morcom died in 1930 from bovine tuberculosis, causing Turing great sorrow. Turing graduated from King's College, Cambridge, and earned a doctorate from Princeton University in 1938.

During World War II, Turing worked for the Government Code and Cypher School at Bletchley Park, leading Hut 8, the section responsible for German naval cryptanalysis. He devised techniques for speeding the breaking of German ciphers, including improvements to the pre-war Polish bomba method, an electromechanical machine that could find settings for the Enigma machine. He played a crucial role in cracking intercepted messages that enabled the Allies to defeat the Axis powers in the Battle of the Atlantic.

After the war, Turing worked at the National Physical Laboratory, designing the Automatic Computing Engine, one of the first designs for a stored-program computer. In 1948, he joined Max Newman's Computing Machine Laboratory at the University of Manchester, contributing to early Manchester computers and becoming interested in mathematical biology. He wrote on the chemical basis of morphogenesis and predicted oscillating chemical reactions such as the Belousov–Zhabotinsky reaction. In 1952, he was prosecuted for homosexual acts and accepted hormone treatment as an alternative to prison. He died from cyanide poisoning; an inquest determined his death as suicide, but the evidence is also consistent with accidental poisoning.

Reader's Guide

Alan Turing left an extensive legacy in mathematics and computing, which has become widely recognised with statues and many things named after him, including an annual award for computing innovation. His portrait appears on the Bank of England £50 note, first released on 23 June 2021. The audience vote in a 2019 BBC series named Turing the greatest scientist of the 20th century. Despite his accomplishments, he was never fully recognised during his lifetime because much of his work was covered by the Official Secrets Act. Following a campaign in 2009, British prime minister Gordon Brown made an official public apology for 'the appalling way [Turing] was treated'. Queen Elizabeth II granted a pardon in 2013. The term 'Alan Turing law' is used informally to refer to a 2017 law in the UK that retroactively pardoned men cautioned or convicted under historical legislation that outlawed homosexual acts. The cognitive scientist Douglas Hofstadter wrote that Turing was in large part responsible not only for the concept of computers, incisive theorems about their powers, and a clear vision of the possibility of computer minds, but also for the cracking of German ciphers during the Second World War, stating 'It is fair to say we owe much to Alan Turing for the fact that we are not under Nazi rule today.'

Did You Know?

• Turing rode his bicycle unaccompanied 60 miles from Southampton to Sherborne to attend school on the first day of the 1926 General Strike.
• He predicted oscillating chemical reactions such as the Belousov–Zhabotinsky reaction, first observed in the 1960s.
• His portrait appears on the Bank of England £50 note, first released on 23 June 2021.
• The term 'Alan Turing law' refers to a 2017 UK law that retroactively pardoned men convicted under historical legislation that outlawed homosexual acts.

Notable Quotes (Wikiquote)

"A man provided with paper, pencil, and rubber, and subject to strict discipline, is in effect a universal machine." — Alan Turing "Intelligent Machinery." This passage was one of the epigraphs to Cryptonomicon, the influential novel by Neal Stephenson, in which Turing was a fictionalized character. It shared a page with a quote from Imelda Marcos." — Alan Turing "'The Mechanical Brain. Answer Found to 300 Year Old Problem' The Times newspaper, 11 June 1949 page 4 column 5." — Alan Turing "The sentence in bold appears on the latest British £50 bank note featuring Alan Turing which was released on 23 June 2021 on what would have been his 109th birthday." — Alan Turing