# Alan Turing ![[50 Resources/51 Attachments/51.03 Public/2026-02-03 Alan Turing.jpg|400]] Alan Turing (1912–1954) was a British mathematician, logician, and cryptanalyst who laid the theoretical foundations for computer science and [[Artificial Intelligence (AI)]]. His 1936 paper "On Computable Numbers" introduced the Turing machine—a theoretical model of computation that defines what can be computed. During World War II, he was instrumental in breaking the German Enigma code at Bletchley Park, helping shorten the war. Turing's 1950 paper "Computing Machinery and Intelligence" proposed the [[Turing Test]] as a criterion for machine intelligence, asking "Can machines think?" His work on morphogenesis (biological pattern formation) was ahead of its time. Despite his contributions, Turing was prosecuted for homosexuality in 1952 and died in 1954, likely by suicide. He received a posthumous royal pardon in 2013, and the ACM Turing Award—computing's highest honor—bears his name. ## Key Contributions | Contribution | Year | Description | |--------------|------|-------------| | **Turing Machine** | 1936 | Theoretical model of computation | | **Halting Problem** | 1936 | Proved some problems are undecidable | | **Enigma Decryption** | 1939-45 | Broke German codes at Bletchley Park | | **Bombe** | 1940 | Electromechanical code-breaking device | | **Turing Test** | 1950 | Test for machine intelligence | | **Morphogenesis** | 1952 | Mathematical biology of pattern formation | | **ACE** | 1945 | Early computer design | ## The Turing Machine A theoretical device that defines computation: - Infinite tape divided into cells - Head that reads/writes symbols - State register controlling behavior - Transition rules determining actions **Church-Turing Thesis**: Anything computable can be computed by a Turing machine. ## Computing Machinery and Intelligence (1950) Turing's seminal AI paper introduced: - **The Imitation Game**: Can a computer fool a human? - **Turing Test**: If a machine's responses are indistinguishable from human, it's intelligent - Anticipated and refuted objections to machine intelligence - Predicted machines would pass the test by 2000 ## World War II Codebreaking At Bletchley Park, Turing: - Led efforts to break Enigma naval codes - Designed the Bombe decryption machine - Helped crack the more complex Lorenz cipher - Estimated to have shortened the war by 2+ years ## Career Timeline - **1912**: Born in London - **1936**: Published "On Computable Numbers" - **1938**: Ph.D. at Princeton under Alonzo Church - **1939**: Joined Bletchley Park - **1945**: Designed ACE computer - **1948**: Joined University of Manchester - **1950**: Published "Computing Machinery and Intelligence" - **1952**: Convicted of "gross indecency" - **1954**: Died in Wilmslow, England - **2013**: Posthumous royal pardon ## Legacy - **Turing Award**: "Nobel Prize of computing" named after him - **Turing completeness**: Measure of computational power - **Turing Test**: Standard reference in AI discussions - **£50 note**: Appears on British currency (2021) ## Quotes <!-- QueryToSerialize: LIST FROM #type/quote AND [[Alan Turing]] WHERE public_note = true SORT file.name ASC --> ## Books <!-- QueryToSerialize: LIST FROM #type/book AND [[Alan Turing]] WHERE public_note = true SORT file.name ASC --> ## References - https://en.wikipedia.org/wiki/Alan_Turing - https://www.turing.org.uk - https://www.britannica.com/biography/Alan-Turing ## Related - [[Turing Test]] - [[Artificial Intelligence (AI)]]