Personal life and substantial works of face of new £50 note have only recently been properly appreciated
Alan Turing, the face of the new £50 note, is recognised as a key figure in
Britain’s codebreaking efforts at Bletchley Park during the second world war, a mathematical genius and even the father of modern computing and artificial intelligence.
The note, expected to enter circulation by the end of 2021, will carry a photo of Turing and feature details relating to his work, including technical drawings for the British Bombe, a device designed by Turing and used during the war to help break German messages encoded using Enigma machines.
It will also reference one of Turing’s academic papers, On computable numbers with an application to the Entscheidungsproblem, in which he essentially envisaged computing machines and showed there are unsolvable problems – propositions that can not be said to be provable or not based only on rules and statements of fact.
Turing’s words will appear in the form of a quote given to the Times in 1949: “This is only a foretaste of what is to come, and only the shadow of what is going to be.”
But Turing’s achievements go beyond what will appear on the note: his work spanned many disciplines including biology and chemistry. Indeed, later in his career Turing wrote a seminal paper explaining how patterns such as spots and stripes can appear during chemical reactions.
While the importance of Turing’s work and the foundations he laid have become increasingly apparent with time, so too have his personal struggles. These have been highlighted in a biography and a number of plays in the 1980s, as well as the 2014 film The Imitation Game, in which Turing was played by Benedict Cumberbatch.
Born in London in 1912, Turing joined Sherborne school at 13. His reports suggest his abilities were mixed, but hint at his imagination and originality. “He must remember that Cambridge will want sound knowledge rather than vague ideas,” his physics teacher wrote.
Turing joined King’s College, Cambridge, in 1931 and became a fellow there in 1935. What followed were a number of seminal ideas, including his vision of a universal computing machine, which can be fed an algorithm for a particular computation and then apply it. It was an idea that was to be pivotal in the development of the computers we use today.
After a stint at Princeton University in America, Turing returned to the UK, where he worked in code-breaking. With the outbreak of war, he joined Bletchley Park.
As a gay man in the early 1950s, at a time when homosexual acts were illegal, Turing faced a demeaning choice when a burglary at his home brought Turing’s relationship with a man to police attention.
He was found guilty of gross indecency and had to decide between going to prison or undergoing chemical castration. He chose the latter, a horrifying treatment that involved hormonal injections.
Turing died in June 1954, aged 41, at his home in Wilmslow, near Manchester, in an apparent suicide. On Christmas Eve in 2013, the Queen signed a posthumous pardon for him.
Turing’s legacy lives on in the machines we take for granted every day, with his name also linked to burgeoning advances. The best known of these is the benchmark Turing test for whether a machine that can think like a human, which hinges on whether human judges can distinguish a computer’s text answers from those given by a person.