/ 9 January 2014

10 Things about Alan Turing

Alan Turing at school in Dorset
Alan Turing at school in Dorset

1 The British scientist, who was a key figure in the invention of the computer as well as a vital code breaker during World War II, was convicted of "gross indecency" 61 years ago, for homosexual activities. Late last year, the queen pardoned him under the royal prerogative of mercy, following a request from Justice Secretary Chris Grayling.

2 Alan Turing's work at the Bletchley Park code-breaking facility was ground-breaking, "arguably shortening the Second World War by at least two years", wrote the Yorkshire Post. He was awarded the Order of the British Empire in 1945.

3 Turing, "often described as the father of modern computing", was "chemically castrated following his conviction in 1952". Such "castration" meant injections of the female hormone oestrogen, which was supposed to suppress the libido.

4 Turing committed suicide two years later by eating some of an apple he had apparently injected with cyanide. He was 41.

5 A campaign to clear the mathematician's name led, most recently, to a petition that gathered more than 37 000 signatures and was supported by Stephen Hawking, among other leading scientists.

6 "In September 2009," writes the Yorkshire Post, "then-Prime Minister Gordon Brown apologised to Dr Turing for [the government's] prosecuting him as a homosexual."

7 Turing was arrested and brought to trial in 1952, writes his bio-grapher, Andrew Hodges, "after the police learned of his sexual relationship with a young Manchester man". Turing "made no serious denial or defence, instead telling everyone that he saw no wrong [in] his actions". 

8 In the 1930s, Turing came up with a solution to what had been called the "Entscheidungsproblem" or "decision problem" since Gottfried Wilhelm von Leibniz made one of the earliest mechanical calculators in the 1670s. Leibniz was trying to teach it direct multiplication when he encountered the problem. The problem was revived and restated in 1928 by the mathematician David Hibbert. It was to this challenge that Turing rose.

9 Turing came up with a conceptual device – the "universal Turing machine" – that would be able to solve a series of problems by means of algorithms. These were dependent on the development of a standard formal language to state the problems and the engineering to make such a machine. The language was found and within a few years engineering began to make such a device possible; hence the birth of the computer.

10 The universal Turing machine, writes Hodges, "embodies the essential principle of the computer: a single machine which can be turned to any well-defined task by being supplied with the appropriate program … [It] embodies the crucial … insight that symbols representing instructions are no different in kind from symbols representing numbers." And from there to Facebook is not such a long way.