Alan Turing


July 6, 2022

Alan Mathison Turing (23 June 1912 – 7 June 1954) was a British mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. Turing was highly influential in the development of modern theoretical computer science, providing a formalization of the concepts of algorithm and computation with the Turing machine, which can be considered a model of a general-purpose computer. He is widely considered the father of theoretical computer science and artificial intelligence. Despite these accomplishments he was never fully recognized in his home country during his lifetime for being homosexual and because much of his work was covered by the Official Secrets Act. During World War II Turing worked for the Government Code and Cipher School (GC&CS) at Bletchley Park, the British cryptanalysis center that produced ultra intelligence. For a time he led Hut 8, the section responsible for German naval cryptanalysis. There he developed several techniques to speed up the breaking of German ciphers, including improvements to the pre-war Polish bombing method, as well as an electromechanical machine that could find settings for the Enigma machine. Turing played a crucial role in breaking intercepted coded messages that enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic, and in doing so helped them win the war. Due to the problems of counterfactual history, it is difficult to estimate the precise effect that ultra intelligence had on warfare, but it has been estimated that this work shortened the war in Europe by more than two years and saved over 14 million lives. After the war Turing worked at the National Physics Laboratory, where he designed the Automatic Computing Engine, one of the first projects for a stored-program computer. In 1948 Turing joined Max Newman's Laboratory of Computing Machines at Victoria University of Manchester, where he helped develop Manchester computers and became interested in mathematical biology. He wrote a paper on the chemical basis of morphogenesis and predicted oscillating chemical reactions, such as the Belousov–Zhabotinsky reaction, first observed in the 1960s. Turing was prosecuted in 1952 for homosexual acts: the Labouchere Amendment of 1885 ruled that "gross indecency" was a criminal offense in the United Kingdom. He accepted chemical castration treatment, with diethylstilbestrol, as an alternative to imprisonment. Turing died in 1954, 16 days short of his 42nd birthday, of cyanide poisoning. An inquest determined his death to be a suicide, but it was noted that the known evidence is also consistent with accidental poisoning. In 2009, following an internet campaign, British Prime Minister Gordon Brown issued a public and official apology to Turing on behalf of the British government for the "terrible way he was treated". Queen Elizabeth II granted Turing a posthumous pardon in 2013. The "Alan Turing Act" is now an informal term for a 2017 British law that retroactively pardoned men warned or convicted under historic legislation that prohibited homosexual acts.

Childhood and education


Turing was born in Maida Vale, London, while his father, Julius Mathison Turing (1873-1947), was on leave from his post with the Indian Civil Service (ICS) in Chatrapur, present-day Odisha, India. Turing's father was the son of a clergyman, the Rev. John Robert Turing, from a Scottish merchant family based in the Netherlands and including a baronet. Turing's mother, Julius' wife, was Ethel Sara Turing (1881–1976), daughter of Edward Waller Stoney, chief engineer of the Madras Railways. The Stoneys were a family of