The renowned mathematician, considered to be the father of the modern computer and credited by Winston Churchill for making “the single biggest contribution to the allied victory”, will adorn the latest version of the UK’s highest-denomination banknote, which is expected to enter circulation in 2021.
Bank of England (BoE) governor Mark Carney chose Turing from a shortlist of 12 after more than 227,000 suggestions of famous British figures were made by the public. The BoE had called for suggestions of British scientists to replace the famous figures on the current £50 note – currently, entrepreneur Matthew Boulton and engineer James Watt, whose steam engine helped power the industrial revolution.
“Alan Turing was an outstanding mathematician whose work has had an enormous impact on how we live today,” Mr Carney said. “As the father of computer science and artificial intelligence, as well as war hero, Alan Turing’s contributions were far-ranging and path-breaking. Turing is a giant on whose shoulders so many now stand.”
Turing played a pivotal role in the development of early computers with his work cracking the Enigma code, and he laid the foundations for artificial intelligence. Despite his enormous achievements, he faced persecution during his life because he was gay. Turing was prosecuted in 1952 for homosexual acts after it was revealed he was in a same-sex relationship.
Faced with the prospect of imprisonment, he accepted the alternative of “chemical castration” – hormone treatment supposed to suppress his sexual desire. He died of cyanide poisoning in 1954 at the age of 41. The mathematician’s housekeeper found him in his bed with a half-eaten apple on a table. His death was recorded as suicide but experts have since questioned the evidence presented during the inquest at the time.
In 2009, then prime minister Gordon Brown made an official apology for the “appalling way” Turing was treated, and in 2013 he was granted a posthumous pardon by the Queen. In 2016 the government unveiled an “Alan Turing law” that posthumously pardoned thousands of gay and bisexual men convicted under outdated gross indecency laws.
The law effectively acted as an apology to those convicted for consensual same-sex relationships before homosexuality was decriminalised in England and Wales in 1967. It came after decades of campaigning from the LGBT+ community and after the family of the Enigma codebreaker delivered a petition to Downing Street before the 2015 general election.
The new note will feature a 1951 photo of Turing, a table and mathematical formulae from one of his most influential scientific papers. It will also feature a picture of the British Bombe code-breaking machine built at Bletchley Park, as well as a quote Turing gave in an interview on 11 June 1949: “This is only a foretaste of what is to come and only the shadow of what is going to be.”
The full note design, including all the security features, will be unveiled closer to it entering circulation. The shortlisted characters, or pairs of characters, considered for the new note were Mary Anning, Paul Dirac, Rosalind Franklin, William Herschel and Caroline Herschel, Dorothy Hodgkin, Ada Lovelace and Charles Babbage, Stephen Hawking, James Clerk Maxwell, Srinivasa Ramanujan, Ernest Rutherford, Frederick Sanger and Alan Turing.
Sarah John, the BoE’s chief cashier, said: “The strength of the shortlist is testament to the UK’s incredible scientific contribution. The breadth of individuals and achievements reflects the huge range of nominations we received for this note and I thank the public for all their suggestions of scientists we could celebrate.”
The new note will be printed on plastic rather than paper as is the current version.
At the outbreak of the Second World War, Turing moved to the Government Code and Cypher School at Bletchley Park where he designed the British Bombe cryptographic machine. Turing’s team played a pivotal role in cracking the German Enigma code, previously seen as unbreakable. They decoded naval and U-boat messages, which revealed information about German positions and helped to shift advantage to the allies during the battle for the Atlantic. Turing was awarded an OBE for his code-breaking work.
After the war Turing worked on designs for pioneering early computers including the Automatic Computing Engine, one of the first electronic stored-programme computers, which was built in 1950 at the National Physical Laboratory in London. At Manchester University’s computing laboratory he developed programming for the Ferranti Mark 1 computer, the world’s first commercially available electronic computer.
While at Manchester he explored artificial intelligence, proposing an experiment which became known as the Turing Test. A machine could be considered able to “think” if a human interrogator was unable to distinguish a machine’s response from that of another human being. He also worked on morphogenetic theory, looking at the mysteries of patterns in nature, for example trying to explain the existence of Fibonacci numbers in plant structures. His paper, “The chemical basis of morphogenesis”, has since been recognised as pioneering work.
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