Alan Turing

Life and legacy

Alan Mathison Turing was born in 1912 in Maida Vale, London, while his father served in the Indian Civil Service. A solitary, brilliant child, he showed early genius in mathematics and science. At King's College, Cambridge, he was elected a Fellow at just twenty-two. In 1936, he published "On Computable Numbers, with an Application to the Entscheidungsproblem," a paper that introduced the concept of the Turing machine - a theoretical device that could simulate any mathematical computation. This paper, written when Turing was twenty-three, is considered the founding document of computer science and established the theoretical limits of what machines can compute.

When war broke out in 1939, Turing was recruited to the Government Code and Cypher School at Bletchley Park. The German military's Enigma machine produced codes that were considered unbreakable - the number of possible settings ran into the billions. Turing designed the Bombe, an electromechanical device that systematically tested Enigma settings to find the day's key. His work, building on earlier Polish cryptanalytic breakthroughs, enabled the Allies to read German naval communications, which was critical to winning the Battle of the Atlantic against U-boats threatening Britain's supply lines. Historians estimate that the intelligence from Bletchley Park shortened the war by at least two years and saved millions of lives.

After the war, Turing worked on the design of early electronic computers at the National Physical Laboratory and then at the University of Manchester, contributing to the development of the Manchester Mark 1, one of the world's first stored-program computers. In 1950, he published "Computing Machinery and Intelligence," which posed the question "Can machines think?" and proposed the Turing test - a measure of machine intelligence based on whether a computer could hold a conversation indistinguishable from a human's. This paper is considered the founding document of artificial intelligence.

In January 1952, Turing was prosecuted for "gross indecency" under British law criminalizing homosexuality. Rather than face imprisonment, he accepted chemical castration through injections of synthetic estrogen. The treatment caused him physical changes and may have affected his mental state. On June 7, 1954, Turing was found dead at his home in Wilmslow, Cheshire, from cyanide poisoning. A half-eaten apple was found beside him. The inquest ruled it suicide, though some, including his mother, believed it was accidental.

Turing received a formal royal pardon in 2013, and in 2017, the "Alan Turing law" retroactively pardoned men convicted under historical anti-homosexuality legislation. His face now appears on the Bank of England £50 note. He is recognized as one of the most important scientists of the twentieth century - a man whose ideas about computation and intelligence shaped the digital world we now inhabit.

Key accomplishments

• Published the foundational paper on computability (1936), introducing the Turing machine concept that defines modern computer science
• Led the team at Bletchley Park that cracked the German Enigma cipher, helping shorten World War II
• Proposed the Turing test for machine intelligence (1950), founding the field of artificial intelligence
• Contributed to the design of early electronic computers including the Manchester Mark 1
• Made pioneering contributions to mathematical biology with his work on morphogenesis

Quotes

We can only see a short distance ahead, but we can see plenty there that needs to be done.

"Computing Machinery and Intelligence," Mind, 1950

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