Alan Turing
Born 1912 · Age 113
English mathematician, logician, cryptanalyst and pioneer of computer science and mathematical biology; key figure at Bletchley Park and originator of the Turing machine and Turing test.
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Life & Career Timeline
Birth in Maida Vale, London
Alan Mathison Turing was born in Maida Vale (Paddington), London. Parents Julius Mathison Turing and Ethel Sara Turing were in the Indian Civil Service family.
Reads Natural Wonders Every Child Should Know
At age ~10 he discovered Edwin Tenney Brewster's book, which Turing credited with opening his eyes to science.
St Michael's primary school attendance
Attended St Michael's primary school in St Leonards-on-Sea from age six to nine.
Hazelhurst Preparatory School
Between January 1922 and 1926 he was educated at Hazelhurst Preparatory School in Frant, Sussex.
Enters Sherborne School (boarding)
At 13 Turing started at Sherborne School in Dorset; famously cycled ~60 miles to attend the first day during the 1926 General Strike.
Studies Einstein's work
By age 15–16 he had grasped Einstein's work and extrapolated aspects of relativity from texts.
Death of Christopher Morcom
Turing's close friend Christopher Morcom died of bovine tuberculosis; the event deeply affected Turing intellectually and personally.
Enters King's College, Cambridge (scholarship)
Won an £80-per-year scholarship to King's College, Cambridge, to study mathematics (Schedule B course).
Undergraduate dissertation delivered (Gaussian error function)
Delivered dissertation 'On the Gaussian error function' proving a version of the central limit theorem; dissertation finally accepted 16 March 1935.
First journal paper published (almost-periodicity)
Published a one-page article 'Equivalence of left and right almost periodicity' in the Journal of the London Mathematical Society (sent 23 April 1935).
Dissertation accepted; elected Fellow of King's College
Dissertation accepted (16 March 1935) and Turing was elected a Fellow of King's College, Cambridge on the strength of his dissertation; he also served as a lecturer.
Smith's Prize awarded
Awarded the Smith's Prize (noted in his honours), recognising his outstanding mathematical work.
Completes 'On Computable Numbers' paper
Finished manuscript 'On Computable Numbers, with an Application to the Entscheidungsproblem' introducing Turing machines and the universal machine concept.
Goes to Princeton University (graduate study)
Spent most of Sep 1936–July 1938 at Princeton under Alonzo Church as a Jane Eliza Procter Visiting Fellow; worked on computability and built electro-mechanical stages of a binary multiplier.
Publishes first part of 'On Computable Numbers'
First part of the landmark paper published in Proceedings of the London Mathematical Society (part 1 on 30 Nov; part 2 on 23 Dec).
Awarded PhD (Systems of Logic Based on Ordinals)
Received PhD from Princeton (June 1938); dissertation introduced ordinal logic and oracle machines (relative computing).
Begins part-time work at Government Code and Cypher School
From Sep 1938 Turing worked part-time for GC&CS (the British codebreaking service), focusing on Enigma cryptanalysis with Dilly Knox.
Specifies the Bombe
Within weeks at Bletchley he specified an electromechanical machine (the bombe) designed to automate Enigma decryption (building on Polish Bomba ideas).
Reports to Bletchley Park full-time
On 4 Sep 1939 (day after UK declared war) Turing reported to Bletchley Park to work full-time on wartime cryptanalysis; signed Official Secrets Act.
Prototype Bombe 'Victory' installed (spring 1940)
Bletchley Park installed an early bombe machine (often referenced as Victory prototype) in spring 1940; bombes subsequently used at scale.
German navy changes operating procedures
In May 1940 Germans changed Enigma indicator procedures (Polish method rendered less effective); Turing's broader bombe approach remained applicable.
Engagement to Joan Clarke; discloses homosexuality
Turing proposed to fellow codebreaker Joan Clarke; he later withdrew the engagement after disclosing he was homosexual.
Hut 8 breaks German naval Enigma
Hut 8 (led by Turing) mastered German naval communication decryption, crucial for Battle of the Atlantic.
Deploys Banburismus statistical method and Tunny techniques
Developed Banburismus for efficient bombe use and Turingery for breaking Lorenz (Tunny) traffic; contributed to large-scale signals intelligence.
Decoding volume milestone at Bletchley Park
By early 1942 Bletchley decoded about 39,000 intercepted messages per month; later rose to over 84,000 per month (two messages per minute).
Travel to United States to liaise (Nov 1942–Mar 1943)
Turing spent Nov 1942–Mar 1943 in the U.S. sharing Enigma knowledge and inspecting Allied speech encryption efforts.
Appointed Officer of the Order of the British Empire (OBE)
Turing was appointed OBE in recognition of his wartime services (officially recorded 1945/1946).
Joins National Physical Laboratory (NPL)
Recruited by NPL to design a stored-program electronic computer; work led to the Automatic Computing Engine (ACE) design.
Submits detailed ACE report (Automatic Computing Engine)
In March 1946 Turing produced a detailed design and report for ACE, a powerful stored-program computer; NPL later judged it over-ambitious.
Returns to Cambridge sabbatical; Pilot ACE built in his absence
Turing took a sabbatical year in 1947; the Pilot ACE was constructed and later executed its first program on 10 May 1950.
Leaves NPL; joins University of Manchester (Newman lab)
In 1948 Turing left NPL and joined Max Newman's Computing Machine Laboratory at the University of Manchester to work on early Manchester computers.
Deputy Director, Computing Laboratory, Manchester
Turing became deputy director (or senior researcher) at Manchester's Computing Machine Laboratory, contributing to software and program design for the Mark 1.
Publishes 'Computing Machinery and Intelligence' (Turing test)
Published the influential paper proposing the imitation game (now the Turing Test), foundational to AI discussions.
Elected Fellow of the Royal Society (FRS)
Elected FRS in recognition primarily of his theoretical work, including the 1936 Turing machine paper.
Begins work on mathematical biology (morphogenesis)
At Manchester he began applying mathematics to biological pattern formation; completed theoretical work predicting chemical oscillations.
Publishes 'The Chemical Basis of Morphogenesis'
Published seminal paper on morphogenesis (pattern formation in biological organisms), predicting reaction-diffusion chemical patterns.
Meets Arnold Murray (relationship leads to later prosecution)
Turing met Arnold Murray and had a relationship; a later burglary and Murray's statements led to police involvement.
Accepts chemical castration (hormone treatment)
To avoid prison he accepted oestrogen hormone injections (chemical castration), which affected his health and career; security clearance revoked.
Tried and convicted for gross indecency
Turing was tried (31 Mar 1952), convicted of gross indecency under UK law for homosexual acts; offered prison or hormonal treatment.
Harassment and security restrictions
After conviction, his GCHQ security clearance was withdrawn; he was investigated and subject to police surveillance; barred from cryptographic work.
Death from cyanide poisoning; inquest suicide verdict
Turing died on 7 June 1954 (found 8 June) from cyanide poisoning; coroner returned a verdict of suicide though accidental poisoning remains plausible.
Statue unveiled in Manchester
A statue honoring Turing was unveiled in Manchester on 23 June 2001 (anniversary of his birthday).
British Prime Minister apologises
Following a campaign, PM Gordon Brown issued an official public apology in 2009 for the 'appalling' way Turing was treated after the war.
Release of wartime mathematical papers
GCHQ-restricted wartime papers by Turing ('The Applications of Probability to Cryptography' and 'Paper on Statistics of Repetitions') were released to the public in April 2012.
Centenary blue plaque and global recognition
Centenary of Turing's birth with events including blue-plaque unveilings (e.g., St Leonards-on-Sea plaque) and wide media coverage.
Posthumous royal pardon granted
Queen Elizabeth II granted Alan Turing a royal pardon in 2013 for his 1952 conviction.
Film 'The Imitation Game' released
Biographical film starring Benedict Cumberbatch as Turing (2014) brought renewed public attention to his life and work.
Alan Turing law (informal usage) and pardons extended
The term 'Alan Turing law' refers to 2017 UK legislation retroactively pardoning men convicted under historic anti-homosexuality laws.
BBC audience names Turing greatest 20th-century scientist
A 2019 BBC public vote named Alan Turing the greatest scientist of the 20th century in an audience poll.
Portrait on Bank of England £50 note released
Turing's portrait was placed on the Bank of England £50 polymer note first released on 23 June 2021 (his birthday).
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