Alan Mathison Turing entered the world in Maida Vale, London, to a father in the Indian civil service. He would grow up to publish the 1936 paper defining the theoretical basis of computation, break the German Enigma cipher at Bletchley Park during World War II, and pioneer questions of machine intelligence, before his 1954 death made him one of science's most mourned tragic figures.
Alan Turing arrived awkwardly early, born prematurely while his parents were between postings in British India, timing his mother had engineered by returning to London specifically so her son would be raised as an Englishman. Nobody watching the delivery could have guessed the boy would eventually reshape what a 'computer' even meant.
At Cambridge and later Princeton, Turing developed the concept of an abstract 'universal machine' that could compute anything computable, a thought experiment now recognized as the theoretical seed of every modern computer. During World War II he applied that same relentless logic at Bletchley Park, leading the team that cracked the German Navy's Enigma code, work later credited with shortening the war and saving countless lives.
His reward from the country he'd helped save was cruelty: prosecuted in 1952 for homosexuality, then a crime in Britain, he was chemically castrated rather than imprisoned. He died in 1954 of cyanide poisoning, ruled a suicide, beside a half-eaten apple. Britain didn't formally apologize until 2009, and only pardoned him in 2013. His birthday is now marked worldwide by computer scientists as a quiet, pointed tribute to how badly a genius can be repaid.
Key people: Alan Turing