Alan Turing
Alan Turing
Alan Mathison Turing (23 June 1912 – 7 June 1954) was a British mathematician, logician, cryptanalyst and computer scientist. He is widely considered to be the father of theoretical computer science and artificial intelligence. During the Second World War, Turing played a crucial role in breaking the ciphers generated by the German Enigma machine at Bletchley Park, using innovative electromechanical devices such as the bombe to decrypt German messages. His work shortened the war and saved countless lives.
After the war, Turing designed the Automatic Computing Engine (ACE), one of the first stored-program computer designs. He also made foundational contributions to the theory of computation through his 1936 paper "On Computable Numbers", which introduced the concept of the Turing machine as an abstract model of computation. In 1950, he published a landmark paper "Computing Machinery and Intelligence", which proposed the Turing test as a criterion for machine intelligence, sparking the modern field of artificial intelligence.
Early life and education
Turing was born in Maida Vale, London, to Julius Mathison Turing and Ethel Sara Stoney. From an early age he showed signs of high intelligence, though his nonconformist nature often frustrated his teachers. He studied at Sherborne School and later at King's College, Cambridge, where he graduated with a first-class degree in mathematics. In 1935, at age 22, he was elected a Fellow of King's College for a dissertation on the central limit theorem. He then studied at Princeton University under Alonzo Church, earning a Ph.D. in 1938 for his work on ordinal logic.
Career and contributions
Cryptanalysis at Bletchley Park
During World War II, Turing worked at the Government Code and Cypher School (GC&CS) at Bletchley Park, where he led Hut 8, the section responsible for German naval cryptanalysis. He developed the bombe, an electromechanical device that helped decode Enigma messages far more rapidly than manual methods. His statistical approach, which he called "Banburismus", allowed effective decryption of naval Enigma traffic, a critical factor in the Battle of the Atlantic.
Contributions to computing
Turing's 1936 paper defined the universal Turing machine, a concept that forms the basis of modern computer architecture. He later worked at the National Physical Laboratory on the ACE, which influenced early computer designs. However, his independence and unorthodox methods sometimes caused friction, leading to a move to the University of Manchester. At Manchester, he contributed to the software for the Manchester Mark 1 and wrote a landmark paper on morphogenesis.
Artificial intelligence and the Turing test
In 1950, Turing proposed a test for machine intelligence, now known as the Turing test. He argued that if a machine could carry on a conversation indistinguishable from a human, it should be considered intelligent. This paper remains a central reference in debates about artificial intelligence and philosophy of mind.
Personal life and prosecution
Turing was an openly gay man at a time when homosexual acts were illegal in the United Kingdom. In 1952, he was convicted of "gross indecency" following an affair with a 19-year-old man. Given the choice between imprisonment and hormonal treatment, he chose chemical castration. He lost his security clearance and was forced to abandon his wartime cryptanalytic work. Turing died of cyanide poisoning in 1954; an inquest ruled it suicide, though the cause remains debated.
Legacy
Turing's contributions were largely unrecognised during his lifetime due to secrecy surrounding his wartime work. In the decades after his death, his importance grew. In 2009, British Prime Minister Gordon Brown issued a formal government apology for Turing's treatment. In 2013, Turing received a posthumous royal pardon under the Royal Prerogative of Mercy. He is commemorated by the Turing Award (the "Nobel Prize of computing") and numerous statues, buildings, and academic programs. His life story inspired the 2014 film The Imitation Game.