Alan Turing

Early life and education: Alan Mathison Turing was born in London in 1912 and educated at private schools before entering King’s College, Cambridge, in 1931 to read mathematics; he was elected to a fellowship at King’s College in 1935 in recognition of his work in probability theory. In 1936 he published “On Computable Numbers, with an Application to the Entscheidungsproblem,” which introduced the abstract “universal machine” (now called the Turing machine) that formalized computation and had profound implications for what can be computed. Academic development and Princeton: After his 1936 work, Turing travelled to Princeton University for doctoral study under Alonzo Church and completed his Ph.D. in mathematical logic in 1938, further solidifying his reputation in theoretical mathematics and logic. His early research established key concepts in computability that later formed the core of theoretical computer science and the Church–Turing thesis. Wartime service at Bletchley Park: At the outbreak of World War II Turing joined the Government Code and Cypher School and in 1939 moved to the wartime codebreaking center at Bletchley Park, where he developed techniques and machines (notably the Bombe, developed with others) to attack the German Enigma cipher; his cryptanalytic work also extended to the German teleprinter cipher (Tunny). His wartime achievements were recognized with an OBE in 1945 for his services to cryptanalysis, though the full scope of his contributions remained secret for decades after the war. Postwar computing and AI work: After the war Turing worked at the National Physical Laboratory, publishing a design for an Automatic Computing Engine (ACE) and later moved to the University of Manchester where he worked on early stored-program computers and wrote the first programming manuals. In 1950 he published “Computing Machinery and Intelligence,” proposing what became known as the Turing Test as an operational criterion for machine intelligence and contributing seminal ideas to the emerging field of artificial intelligence and cognitive science. Personal life, prosecution, and legacy: Turing was prosecuted in 1952 for homosexual acts (then a criminal offence in the UK); he accepted chemical castration as an alternative to prison, and his conviction led to loss of security clearance and curtailed work opportunities. He died in 1954 from cyanide poisoning in circumstances that the coroner recorded as probable suicide; Turing’s contributions were later publicly acknowledged, and he has since been widely honored, pardoned posthumously, and memorialized for both scientific achievements and the injustice he suffered.