Alan Turing: Difference between revisions

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* [[Princeton University]] ([[Doctor of Philosophy|PhD]])

'''Alan Mathison Turing''' {{post-nominals|country=GBR|size=100%|OBE|FRS}} ({{IPAc-en|ˈ|tj|ʊər|ɪ|ŋ}}; 23 June 1912&nbsp;– 7 June 1954) was an English mathematician, [[computer scientist]], [[logic]]ian, [[cryptanalysis|cryptanalyst]], [[philosophy|philosopher]] and [[mathematical and theoretical biology|theoretical biologist]].<ref>{{cite web |title=Alan Turing |url=https://www.bl.uk/people/alan-turing |url-status= |archive-url=https://web.archive.org/web/20190723191531/https://www.bl.uk/people/alan-turing |archive-date=23 July 2019 |access-date=29 July 2019 |publisher=The British Library}}</ref> TuringHe was highly influential in the development of [[theoretical computer science]], providing a formalisation of the concepts of [[algorithm]] and [[computation]] with the [[Turing machine]], which can be considered a model of a general-purpose [[computer]].<ref name="frs">{{Cite journal

|issn = 0080-4606}}</ref><ref name="AFP">{{cite news |last=Gray |first=Paul |date=29 March 1999 |title=Computer Scientist: Alan Turing |magazine=Time |url=http://www.time.com/time/magazine/article/0,9171,990624,00.html |url-status=dead |access-date=10 January 2011 |archive-url=https://web.archive.org/web/20110119181237/http://www.time.com/time/magazine/article/0,9171,990624,00.html |archive-date=19 January 2011 |quote=Providing a blueprint for the electronic digital computer. The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine.}}</ref><ref>{{Harvnb|Sipser|2006|p=137}}</ref> HeTuring is widely considered to be the father of theoretical computer science.<ref>{{Harvnb|Beavers|2013|p=481}}</ref>

Born in London, Turing was raised in [[southern England]]. He graduated in maths from [[University of Cambridge|King's College, Cambridge]], and in 1938, earned a mathsdoctorate PhDdegree from [[Princeton University]]. During the Second [[World War II]], Turing worked for the [[Government Code and Cypher School]] at [[Bletchley Park]], Britain's [[codebreaking]] centre that produced [[Ultra (cryptography)|Ultra]] intelligence. He led [[Hut 8]], the section responsible for German naval cryptanalysis. HeTuring devised techniques for speeding the breaking of German [[cipher]]s, including improvements to the pre-war Polish [[Bomba (cryptography)|bomba]] method, an [[electromechanics|electromechanical]] machine that could find settings for the [[Enigma machine]]. TuringHe played a crucial role in cracking intercepted messages that enabled the Allies to defeat the [[Axis powers]] in many crucial engagements, including the [[Battle of the Atlantic]].<ref name="bbc-copeland">{{cite news|last=Copeland|first=Jack|author-link=Jack Copeland|date=18 June 2012|title=Alan Turing: The codebreaker who saved 'millions of lives'|publisher=BBC News Technology|url=https://www.bbc.com/news/technology-18419691|url-status=live|access-date=26 October 2014|archive-url=https://web.archive.org/web/20141011045451/http://www.bbc.com/news/technology-18419691|archive-date=11 October 2014}}</ref><ref>A number of sources state that Winston Churchill said that Turing made the single biggest contribution to Allied victory in the war against Nazi Germany. HoweverWhilst it may be a defensible claim, both the [[Churchill Centre]] and Turing's biographer [[Andrew Hodges]] have stated they know of no documentary evidence to support this claimit, nor of the date or context in which Churchill supposedly saidmade it, and the Churchill Centre lists it among their Churchill 'Myths', see {{cite web |last=Schilling |first=Jonathan |date=8 January 2015 |title=Myths > Churchill Said Turing Made the Single Biggest Contribution to Allied Victory |url=http://www.winstonchurchill.org/resources/myths/churchill-said-turing-made-the-single-biggest-contribution-to-allied-victory |url-status= |archive-url=https://web.archive.org/web/20150217170510/http://www.winstonchurchill.org/resources/myths/churchill-said-turing-made-the-single-biggest-contribution-to-allied-victory |archive-date=17 February 2015 |access-date=9 January 2015 |publisher=The Churchill Centre }} and {{cite web |last=Hodges |first=Andrew |author-link=Andrew Hodges |title=Part 4: The Relay Race |url=http://www.turing.org.uk/book/update/part4.html |url-status=live |archive-url=https://web.archive.org/web/20150120190931/http://www.turing.org.uk/book/update/part4.html |archive-date=20 January 2015 |access-date=9 January 2015 |publisher=Update to [[Alan Turing: The Enigma]] }} A [[BBC News]] profile piece that repeated the Churchill claim has subsequently been amended to say there is no evidence for it. See {{cite news |last=Spencer |first=Clare |date=11 September 2009 |title=Profile: Alan Turing |work=BBC News |url=http://news.bbc.co.uk/2/hi/uk_news/8250592.stm |url-status=live |access-date=17 February 2015 |archive-url=https://web.archive.org/web/20171213095303/http://www.bbc.com/news/technology-18419691 |archive-date=13 December 2017 |quote=Update 13 February 2015 }} Official war historian [[Harry Hinsley]] estimated that this work shortened the war in Europe by more than two years but added the caveat that this did not account for the [[Manhattan Project|use of the atomic bomb]] and other eventualities. {{citation |last=Hinsley |first=Harry |title=The Influence of ULTRA in the Second World War |url=http://www.cix.co.uk/~klockstone/hinsley.htm |year=1996 |publisher=Keith Lockstone's home page |author-link=Harry Hinsley |origyear=1993 |access-date=26 August 2024 |archive-date=15 October 2022 |archive-url=https://web.archive.org/web/20221015210957/https://www.cix.co.uk/~klockstone/hinsley.htm |url-status=live }} Transcript of a lecture given on Tuesday 19 October 1993 at Cambridge University</ref>

After the war, Turing worked at the [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]], where he designed the [[Automatic Computing Engine]], one of the first designs for a stored-program computer. In 1948, Turing joined [[Max Newman]]'s [[Computing Machine Laboratory]] at the [[Victoria University of Manchester]], where he helped develop the [[Manchester computers]]<ref>{{Harvnb|Leavitt|2007|pp=231–233}}</ref> and became interested in [[Mathematical and theoretical biology|mathematical biology]]. HeTuring wrote on the chemical basis of [[morphogenesis]]<ref name="Milinkovitch">{{cite journal |last1=Milinkovitch |first1=Michel C. |last2=Jahanbakhsh |first2=Ebrahim |last3=Zakany |first3=Szabolcs |title=The Unreasonable Effectiveness of Reaction Diffusion in Vertebrate Skin Color Patterning |journal=Annual Review of Cell and Developmental Biology |date=16 October 2023 |volume=39 |issue=1 |pages=145–174 |doi=10.1146/annurev-cellbio-120319-024414 |language=en |issn=1081-0706|doi-access=free |pmid=37843926 }}</ref><ref name="googlescholar" /> and predicted [[Chemical oscillator|oscillating chemical reactions]] such as the [[Belousov–Zhabotinsky reaction]], first observed in the 1960s. Despite these accomplishments, Turinghe was never fully recognised during his lifetime because much of his work was covered by the [[Official Secrets Act 1939|Official Secrets Act]].<ref>{{Cite book |last=Olinick |first=Michael |year=2021 |title=Simply Turing |location=United States |publisher=Simply Charly |chapter=Chapter 15}}</ref>

In 1952, Turing was prosecuted in 1952 for [[Gross indecency|homosexual acts]]. He accepted hormone treatment, a procedure commonly referred to as [[chemical castration]], as an alternative to prison. Turing died on 7 June 1954, aged 41, from [[cyanide poisoning]]. An inquest determined [[List of LGBT-related suicides|his death as suicide]], but the evidence is also consistent with accidental poisoning.<ref name = "Copeland" />

Turing hasleft an [[Legacy of Alan Turing|extensive legacy]] in mathematics and computing which today is recognised more widely, with statues and [[List of things named after Alan Turing|many things named after him]], including an [[Turing Award|annual award]] for computercomputing science innovationsinnovation. HeHis portrait appears on the current [[Bank of England £50 note]], which wasfirst released on 23 June 2021 to coincide with his birthday. AThe audience vote in a, [[Icons: The Greatest Person of the 20th Century|2019 BBC series]], as voted by the audience, named himTuring the greatest person of the 20th century.

Turing was born in [[Maida Vale]], London, while his father, Julius Mathison Turing, was on leave from his position with the [[Indian Civil Service]] (ICS) of the [[British Raj|British Raj government]] at [[Chatrapur]], then in the [[Madras Presidency]] and presently in [[Odisha]] state, in [[India]].<ref name = "Hodges1983P5">{{Harvnb|Hodges|1983|p=5}}</ref><ref>{{cite web |url=http://www.turing.org.uk/turing/scrapbook/early.html |title=The Alan Turing Internet Scrapbook |publisher=[[Alan Turing: The Enigma]] |access-date=2 January 2012 |archive-url=https://web.archive.org/web/20120614051614/http://www.turing.org.uk/turing/scrapbook/early.html |archive-date=14 June 2012 |url-status=live }}</ref> Turing's father was the son of a clergyman, the Rev.&nbsp;John Robert Turing, from a Scottish family of merchants that had been based in the Netherlands and included a [[baronet]]. Turing's mother, Julius's wife, was Ethel Sara Turing ({{nee|Stoney}}), daughter of Edward Waller Stoney, chief engineer of the [[Madras and Southern Mahratta Railway|Madras Railways]]. The Stoneys were a [[Protestantism in Ireland|Protestant]] [[Anglo-Irish people|Anglo-Irish]] [[gentry]] family from both [[County Tipperary]] and [[County Longford]], while Ethel herself had spent much of her childhood in [[County Clare]].<ref>{{Cite news |first=Phil |last=Maguire |title=An Irishman's Diary |page=5 |newspaper=[[The Irish Times]] |date=23 June 2012}}</ref> Julius and Ethel married on 1 October 1907 at the Church of Ireland [[St Bartholomew's Church, Dublin|St. Bartholomew's Church]] on [[Clyde Road]] in [[Ballsbridge]], [[Dublin]].<ref>Irish Marriages 1845–1958 / Dublin South, Dublin, Ireland / Group Registration ID 1990366, SR District/Reg Area, Dublin South</ref>

Very early in life, Turing showed signs of the genius that he was later to display prominently.<ref name=toolbox>{{cite web |title=Alan Turing&nbsp;– Towards a Digital Mind: Part 1 |first=G. James |last=Jones |date=11 December 2001 |url=http://www.systemtoolbox.com/article.php?history_id=3 |access-date=27 July 2007 |work=System Toolbox |archive-url=https://web.archive.org/web/20070803163318/http://www.systemtoolbox.com/article.php?history_id=3 |archive-date=3 August 2007 |url-status=dead}}</ref> His's parents purchased a house in [[Guildford]] in 1927, and Turing lived there during school holidays. The location is also marked with a blue plaque.<ref>{{cite web |url=http://www.guildford-dragon.com/2012/11/29/founder-of-computer-science-alan-turings-guildford-stargazing/ |title=Guildford Dragon NEWS |publisher=The Guildford Dragon |date=29 November 2012 |access-date=31 October 2013 |archive-url=https://web.archive.org/web/20131019062927/http://www.guildford-dragon.com/2012/11/29/founder-of-computer-science-alan-turings-guildford-stargazing/ |archive-date=19 October 2013 |url-status=live }}</ref>

Turing's parents enrolled him at St Michael's, a primary school at 20 Charles Road, [[St Leonards-on-Sea]], from the age of six to nine. The headmistress recognised his talent, noting that she has "...had clever boys and hardworking boys, but Alan is a genius".<ref>{{Cite book|last=Cawthorne|first=Nigel|url=https://www.worldcat.org/oclc/890938716|title=Alan Turing : the enigma man|date=2014|isbn=978-1-78404-535-7|location=London|publisher=Arcturus Publishing|pages=18|oclc=890938716|access-date=26 August 2024|archive-date=17 November 2021|archive-url=https://web.archive.org/web/20211117213134/https://www.worldcat.org/title/alan-turing-the-enigma-man/oclc/890938716|url-status=live}}</ref>

Between January 1922 and 1926, Turing was educated at Hazelhurst Preparatory School, an independent school in the village of [[Frant]] in Sussex (now [[East Sussex]]).<ref>{{cite web|url=http://oldshirburnian.org.uk/wp-content/uploads/2016/04/TURING-Alan-Mathison.pdf|title=Alan Turing Archive – Sherborne School (ARCHON CODE: GB1949)|author=Alan Mathison|work=Sherborne School, Dorset|date=April 2016|access-date=5 February 2017|archive-url=https://web.archive.org/web/20161226093015/http://oldshirburnian.org.uk/wp-content/uploads/2016/04/TURING-Alan-Mathison.pdf|archive-date=26 December 2016|url-status=live}}</ref> In 1926, at the age of 13, he went on to [[Sherborne School]],<ref>{{Cite web|date=1 September 2016|title=Alan Turing OBE, PhD, FRS (1912–1954)|url=https://oldshirburnian.org.uk/alan-turing/|access-date=10 October 2020|website=The Old Shirburnian Society|language=en-GB|archive-date=4 November 2020|archive-url=https://web.archive.org/web/20201104133822/https://oldshirburnian.org.uk/alan-turing/|url-status=live}}</ref> an independent boarding school in the market town of [[Sherborne]] in Dorset, where he boarded at Westcott House. The first day of term coincided with the [[1926 United Kingdom general strike|1926 General Strike]], in Britain, but Turing was so determined to attend that he rode his bicycle unaccompanied {{convert|60|mi|km}} from [[Southampton]] to Sherborne, stopping overnight at an inn.<ref name=metamagical>{{Cite book|title=Metamagical Themas: Questing for the Essence of Mind and Pattern |page=[https://books.google.com/books?id=o8jzWF7rD6oC&pg=PA484 484]|first=Douglas R. |last=Hofstadter |year=1985 |publisher=Basic Books |isbn=978-0-465-04566-2 |oclc=230812136}}</ref>

At Sherborne, Turing formed a significant friendship with fellow pupil Christopher Collan Morcom (13 July 1911 – 13 February 1930),<ref>{{Cite web|url=https://oldshirburnian.org.uk/wp-content/uploads/2015/01/Obituary-for-Christopher-Morcom-The-Shirburnian-March-1930.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://oldshirburnian.org.uk/wp-content/uploads/2015/01/Obituary-for-Christopher-Morcom-The-Shirburnian-March-1930.pdf |archive-date=9 October 2022 |url-status=live|title=''The Shirburnian''}}</ref> who has been described as Turing's first love.<ref>{{cite book |title=The Alyson Almanac: A Treasury of Information for the Gay and Lesbian Community |date=1989 |publisher=Alyson Publications |isbn=978-0-932870-19-3 |page=192 |url=https://books.google.com/books?id=v-8gAQAAMAAJ |language=en |quote=After his first love, Christopher Morcom, died of tuberculosis ... |access-date=26 August 2024 |archive-date=7 November 2023 |archive-url=https://web.archive.org/web/20231107005431/https://books.google.com/books?id=v-8gAQAAMAAJ |url-status=live }}</ref><ref>{{cite book |last1=Hodges |first1=Andrew |title=Alan Turing: The Enigma |date=1992 |publisher=Vintage |isbn=978-0-09-911641-7 |page=35 |url=https://books.google.com/books?id=VWvPIWm75XIC |quote=This was first love, which Alan would himself come to regard as the first of many for others of his own sex. |access-date=26 August 2024 |archive-date=8 September 2023 |archive-url=https://web.archive.org/web/20230908030210/https://books.google.com/books?id=VWvPIWm75XIC |url-status=live }}</ref><ref>{{cite book |title=Tekhnema: Journal of Philosophy and Technology |date=1995 |publisher=American University of Paris |page=57 |url=https://books.google.com/books?id=wkvGAAAAIAAJ |quote=... Turing's first platonic love, Christopher Morcom ...}}</ref> Their relationship provided inspiration in Turing's future endeavours, but it was cut short by Morcom's death, in February 1930, from complications of [[bovine tuberculosis]], contracted after drinking infected cow's milk some years previously.<ref name=NYReviewBooks>{{cite web|author=Caryl, Christian|title=Poor Imitation of Alan Turing|url=http://www.nybooks.com/blogs/nyrblog/2014/dec/19/poor-imitation-alan-turing/|newspaper=[[New York Review of Books]]|date=19 December 2014|access-date=9 January 2015|archive-url=https://web.archive.org/web/20150107010418/http://www.nybooks.com/blogs/nyrblog/2014/dec/19/poor-imitation-alan-turing/|archive-date=7 January 2015|url-status=live}}</ref><ref>{{cite web |first=Rachel |last=Hassall |url=http://oldshirburnian.org.uk/wp-content/uploads/2014/03/The-Sherborne-Formula-Vivat-2012-2013-optimised.pdf |title=The Sherborne Formula: The Making of Alan Turing |archive-url=https://web.archive.org/web/20140415082353/http://oldshirburnian.org.uk/wp-content/uploads/2014/03/The-Sherborne-Formula-Vivat-2012-2013-optimised.pdf |archive-date=15 April 2014 |work=Vivat! |date=2012–2013}}</ref><ref name=teuscher>{{Cite book|editor-last=Teuscher |editor-first=Christof|editor-link=Christof Teuscher |title=Alan Turing: Life and Legacy of a Great Thinker |year=2004 |publisher=[[Springer Science+Business Media|Springer-Verlag]] |isbn=978-3-540-20020-8 |oclc=53434737 }}</ref>

The event caused Turing great sorrow. He coped with his grief by working that much harder on the topics of science and mathematics that he had shared with Morcom. In a letter to Morcom's mother, Frances Isobel Morcom (née Swan), Turing wrote:{{blockquote|I am sure I could not have found anywhere another companion so brilliant and yet so charming and unconceited. I regarded my interest in my work, and in such things as astronomy (to which he introduced me) as something to be shared with him and I think he felt a little the same about me&nbsp;... I know I must put as much energy if not as much interest into my work as if he were alive, because that is what he would like me to do.<ref>{{Harvnb|Hodges|1983|p=61}}</ref>}}

After graduating from Sherborne, Turing applied for several Cambridge colleges scholarships, including [[Trinity College, Cambridge|Trinity]] and [[King's College, Cambridge|King's]], eventually earning an £80 per annum scholarship (equivalent to about £4,300 as of 2023) to study at the latter.<ref>{{cite book |last1=Hodges |first1=Andrew |title=Alan Turing: The Enigma |date=10 November 2014 |publisher=Princeton University Press |isbn=978-0-691-16472-4 |pages=74–5 |edition=2014}}</ref><ref>{{cite web | url=https://www.bankofengland.co.uk/monetary-policy/inflation/inflation-calculator | title=Inflation calculator | access-date=26 August 2024 | archive-date=5 October 2018 | archive-url=https://web.archive.org/web/20181005211045/https://www.bankofengland.co.uk/monetary-policy/inflation/inflation-calculator | url-status=live }}</ref> There, Turing studied the undergraduate course in Schedule B (that is, a three-year Parts I and II, of the [[Mathematical Tripos]], with extra courses at the end of the third year, as Part III only emerged as a separate degree in 1934) from February 1931 to November 1934 at [[King's College, Cambridge]], where he was awarded first-class honours in mathematics. His dissertation, ''On the Gaussian error function'', written during his senior year and delivered in November 1934 (with a deadline date of 6 December) proved a version of the [[central limit theorem]]. It was finally accepted on 16 March 1935. By spring of that same year, Turing started his master's course (Part III)—which he completed in 1937—and, at the same time, he published his first paper, a one-page article called ''Equivalence of left and right almost periodicity'' (sent on 23 April), featured in the tenth volume of the ''[[London Mathematical Society|Journal of the London Mathematical Society]]''.<ref>{{cite web | url=https://turingarchive.kings.cam.ac.uk/publications-lectures-and-talks-amtb/amt-b-10 | title=AMT-B-10 &#124; the Turing Digital Archive }}</ref> Later that year, Turing was elected a [[Fellow]] of King's College on the strength of his dissertation<ref>{{Cite journal |last=Aldrich |first=John |date=December 2009 |title=England and Continental Probability in the Inter-War Years |journal=Electronic Journ@l for History of Probability and Statistics |volume=5 |number=2 |url=https://www.jehps.net/Decembre2009/Aldrich.pdf |pages=7–11}}</ref> where he served as a [[lecturer]].<ref name=lecturer>{{cite web|first=Alan|last=Turing|year=1939|url=https://archivesearch.lib.cam.ac.uk/repositories/7/archival_objects/272543|website=cam.ac.uk|title=Letter From Alan Turing to his mother, Sara Turing, 1939-01-23|quote=“My lectures are going off rather well. There are 14 people coming to them at present. No doubt the attendance will drop off as the term advances.”}}</ref> However, and, unknown to Turing, this version of the theorem he proved in his paper, had already been proven, in 1922, by [[Jarl Waldemar Lindeberg]]. Despite this, the committee found Turing's methods original and so regarded the work worthy of consideration for the fellowship. [[Abram Besicovitch]]'s report for the committee went so far as to say that if Turing's work had been published before Lindeberg's, it would have been "an important event in the mathematical literature of that year".<ref>{{cite book |last=Turing |first=Dermot |author-link=Dermot Turing |title=[[Prof: Alan Turing Decoded]] |year=2015 |publisher=[[The History Press]] |isbn=9781841656434 |page= 69}}</ref>{{sfn|Hodges|1983|p=113}}<ref>{{cite journal|title=Alan Turing and the Central Limit Theorem |first=S. L. |last=Zabell |pages=483–494 |journal=The American Mathematical Monthly |volume=102 |year=1995 |number=6 |doi=10.1080/00029890.1995.12004608}}</ref>

Although [[Turing's proof]] was published shortly after [[Alonzo Church]]'s equivalent proof using his [[lambda calculus]],<ref>{{Harvnb|Church|1936}}</ref> Turing's approach is considerably more accessible and intuitive than Church's.<ref>{{cite web|last1=Grime|first1=James|title=What Did Turing Do for Us?|url=https://nrich.maths.org/8050|website=[[NRICH]]|publisher=[[University of Cambridge]]|access-date=28 February 2016|date=February 2012|archive-url=https://web.archive.org/web/20160304175703/http://nrich.maths.org/8050|archive-date=4 March 2016|url-status=live}}</ref> It also included a notion of a 'Universal Machine' (now known as a [[universal Turing machine]]), with the idea that such a machine could perform the tasks of any other computation machine (as indeed could Church's lambda calculus). According to the [[Church–Turing thesis]], Turing machines and the lambda calculus are capable of computing anything that is computable. [[John von Neumann]] acknowledged that the central concept of the modern computer was due to Turing's paper.<ref>"von Neumann&nbsp;... firmly emphasised to me, and to others I am sure, that the fundamental conception is owing to Turing—insofar as not anticipated by Babbage, Lovelace and others." Letter by [[Stanley Frankel]] to [[Brian Randell]], 1972, quoted in [[Jack Copeland]] (2004) ''The Essential Turing'', p.&nbsp;22.</ref> To this day, Turing machines are a central object of study in [[theory of computation]].<ref>{{Citation |last=De Mol |first=Liesbeth |title=Turing Machines |date=2021 |url=https://plato.stanford.edu/archives/win2021/entries/turing-machine/ |encyclopedia=The Stanford Encyclopedia of Philosophy |editor-last=Zalta |editor-first=Edward N. |access-date=2023-07-12 July 2023 |edition=Winter 2021 |publisher=Metaphysics Research Lab, Stanford University |archive-url= https://web.archive.org/web/20221016224306/https://plato.stanford.edu/archives/win2021/entries/turing-machine/ |archive-date= 16 October 2022 |url-status=live }}</ref>

}}</ref> his dissertation, ''[[Systems of Logic Based on Ordinals]]'',<ref name="turingphd">{{cite thesis |degree=PhD |first=Alan|last=Turing |title=Systems of Logic Based on Ordinals|journal=Proceedings of the London Mathematical Society |publisher=Princeton University |year=1938 |volume=s2-45 |issue=1 |doi=10.1112/plms/s2-45.1.161|author-link=Alan Turing|id={{ProQuest|301792588}}|hdl=21.11116/0000-0001-91CE-3|hdl-access=free}}</ref><ref>{{cite web | last = Turing | first = A.M. | author-link = Alan Turing | title = Systems of Logic Based on Ordinals | year = 1938 | url = https://webspace.princeton.edu/users/jedwards/Turing%20Centennial%202012/Mudd%20Archive%20files/12285_AC100_Turing_1938.pdf | access-date = 4 February 2012 | archive-url = https://web.archive.org/web/20121023103503/https://webspace.princeton.edu/users/jedwards/Turing%20Centennial%202012/Mudd%20Archive%20files/12285_AC100_Turing_1938.pdf | archive-date = 23 October 2012 | url-status = dead }}</ref> introduced the concept of [[ordinal logic]] and the notion of [[Turing reduction|relative computing]], in which Turing machines are augmented with so-called [[oracle machine|oracles]], allowing the study of problems that cannot be solved by Turing machines. John von Neumann wanted to hire him as his [[Postdoctoral researcher|postdoctoral assistant]], but he went back to the United Kingdom.<ref>''John Von Neumann: The Scientific Genius Who Pioneered the Modern Computer, Game Theory, Nuclear Deterrence, and Much More'', Norman MacRae, 1999, American Mathematical Society, Chapter 8</ref>

On 4 September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GC&CS.<ref name=Copeland2006p378>Copeland, 2006 p.&nbsp;378.</ref> Like all others who came to Bletchley, he was required to sign the [[Official Secrets Act 1939|Official Secrets Act]], in which he agreed not to disclose anything about his work at Bletchley, with severe legal penalties for violating the Act.<ref name="Collins">{{cite web |last=Collins |first=Jeremy |title=Alan Turing and the Hidden Heroes of Bletchley Park: A Conversation with Sir John Dermot Turing |date=24 June 2020 |location=New Orleans |publisher=The National WWII Museum |url=https://www.nationalww2museum.org/war/articles/alan-turing-betchley-park |access-date=24 August 2021 |archive-date=2 December 2021 |archive-url=https://web.archive.org/web/20211202101721/https://www.nationalww2museum.org/war/articles/alan-turing-betchley-park |url-status=live }}</ref>

Specifying the bombe was the first of five major cryptanalytical advances that Turing made during the war. The others were: deducing the indicator procedure used by the German navy; developing a statistical procedure dubbed ''[[Banburismus]]'' for making much more efficient use of the bombes; developing a procedure dubbed ''[[Turingery]]'' for working out the cam settings of the wheels of the [[Lorenz SZ 40/42]] (''Tunny'') cipher machine and, towards the end of the war, the development of a portable [[secure voice]] scrambler at [[Her Majesty's Government Communications Centre|Hanslope Park]] that was codenamed ''Delilah''.<ref>{{Cite web |title=How Alan Turing Cracked The Enigma Code |url=https://www.iwm.org.uk/history/how-alan-turing-cracked-the-enigma-code |access-date=2023-07-12 July 2023 |website=Imperial War Museums |language=en |archive-date=24 January 2022 |archive-url=https://web.archive.org/web/20220124140731/https://www.iwm.org.uk/history/how-alan-turing-cracked-the-enigma-code |url-status=live }}</ref><ref>{{Cite journal |last1=Turing |first1=Alan M. |last2=Bayley |first2=D. |date=2012 |title=Report on Speech Secrecy System DELILAH, a Technical Description Compiled by A. M. Turing and Lieutenant D. Bayley REME, 1945–1946 |url=http://www.tandfonline.com/doi/abs/10.1080/01611194.2012.713803 |journal=Cryptologia |language=en |volume=36 |issue=4 |pages=295–340 |doi=10.1080/01611194.2012.713803 |s2cid=205488183 |issn=0161-1194 |access-date=26 August 2024 |archive-date=12 July 2023 |archive-url=https://web.archive.org/web/20230712092022/https://www.tandfonline.com/doi/abs/10.1080/01611194.2012.713803 |url-status=live }}</ref>

By using statistical techniques to optimise the trial of different possibilities in the code breaking process, Turing made an innovative contribution to the subject. He wrote two papers discussing mathematical approaches, titled ''The Applications of Probability to Cryptography''<ref>{{cite web | last = Turing | first = Alan | year = c. 1941 | title = The Applications of Probability to Cryptography | id = The National Archives (United Kingdom): HW 25/37 | url = http://discovery.nationalarchives.gov.uk/details/r/C11510465 | access-date = 25 March 2015 | archive-url = https://web.archive.org/web/20150407234050/http://discovery.nationalarchives.gov.uk/details/r/C11510465 | archive-date = 7 April 2015 | url-status = live }}</ref> and ''Paper on Statistics of Repetitions'',<ref>{{cite web | last = Turing | first = Alan | year = c. 1941 | title = Paper on Statistics of Repetitions | id = The National Archives (United Kingdom): HW 25/38 | url = http://discovery.nationalarchives.gov.uk/details/r/C11510466 | access-date = 25 March 2015 | archive-url = https://web.archive.org/web/20150408013845/http://discovery.nationalarchives.gov.uk/details/r/C11510466 | archive-date = 8 April 2015 | url-status = live }}</ref> which were of such value to GC&CS and its successor [[Government Communications Headquarters|GCHQ]] that they were not released to the [[The National Archives (United Kingdom)|UK National Archives]] until April 2012, shortly before the centenary of his birth. A GCHQ mathematician, "who identified himself only as Richard," said at the time that the fact that the contents had been restricted under the Official Secrets Act for some 70 years demonstrated their importance, and their relevance to post-war cryptanalysis:<ref name=bbcrichard>{{cite news |last=Vallance |first=Chris |title=Alan Turing papers on code breaking released by GCHQ |url=https://www.bbc.co.uk/news/technology-17771962 |access-date=20 April 2012 |work=BBC News |date=19 April 2012 |archive-url=https://web.archive.org/web/20121004192554/http://www.bbc.co.uk/news/technology-17771962 |archive-date=4 October 2012 |url-status=live }}</ref>

{{blockquote|text=[He] said the fact that the contents had been restricted "shows what a tremendous importance it has in the foundations of our subject". ... The papers detailed using "mathematical analysis to try and determine which are the more likely settings so that they can be tried as quickly as possible". ... Richard said that GCHQ had now "squeezed the juice" out of the two papers and was "happy for them to be released into the public domain".}}

While working at Bletchley, Turing, who was a talented [[Long-distance running|long-distance runner]], occasionally ran the {{convert|40|mi}} to London when he was needed for meetings,<ref>{{Cite book | last = Brown | first = Anthony Cave | author-link = Anthony Cave Brown | title = Bodyguard of Lies: The Extraordinary True Story Behind D-Day | page = 19 | publisher=The Lyons Press | year = 1975 | isbn = 978-1-59921-383-5 | url = https://archive.org/details/bodyguardoflies00brow | url-access = registration}}</ref> and he was capable of world-class marathon standards.<ref>{{cite news|url=https://www.theguardian.com/commentisfree/2010/mar/10/alan-turing-2012-olympics|title=An Olympic honour for Alan Turing|author=Graham-Cumming, John|newspaper=The Guardian|date=10 March 2010|location=London|access-date=10 December 2016|archive-url=https://web.archive.org/web/20161201171628/https://www.theguardian.com/commentisfree/2010/mar/10/alan-turing-2012-olympics|archive-date=1 December 2016|url-status=live}}</ref><ref>{{cite web | first=Pat | last=Butcher | url=http://www.globerunner.org/index.php/09/in-praise-of-great-men/ | title=In Praise of Great Men | publisher=Globe Runner | date=14 September 2009 | access-date=23 June 2012 | archive-url=https://web.archive.org/web/20130818145759/http://www.globerunner.org/index.php/09/in-praise-of-great-men/ | archive-date=18 August 2013 | url-status=live }}</ref> Turing tried out for the [[Great Britain at the 1948 Summer Olympics|1948 British Olympic team]], but he was hampered by an injury. His tryout time for the marathon was only 11 minutes slower than British silver medallist [[Tom Richards (athlete)|Thomas Richards]]' Olympic race time of 2 hours 35 minutes. He was Walton Athletic Club's best runner, a fact discovered when he passed the group while running alone.<ref>{{cite web | last1 = Hodges | first1 = Andrew | author-link = Andrew Hodges | title = Alan Turing: a short biography | url = http://www.turing.org.uk/bio/part6.html | publisher = Alan Turing: The Enigma | access-date = 12 June 2014 | archive-url = https://web.archive.org/web/20130914091359/http://www.turing.org.uk/bio/part6.html | archive-date = 14 September 2013 | url-status = live }}</ref><ref>{{cite news | last1 = Graham-Cumming | first1 = John | author-link = John Graham-Cumming | title = Alan Turing: a short biography | url = https://www.theguardian.com/commentisfree/2010/mar/10/alan-turing-2012-olympics | newspaper = The Guardian | date = 10 March 2010 | access-date = 12 June 2014 | archive-url = https://web.archive.org/web/20141108165218/http://www.theguardian.com/commentisfree/2010/mar/10/alan-turing-2012-olympics | archive-date = 8 November 2014 | url-status = live }}</ref><ref>{{cite web | last1 = Butcher | first1 = Pat | title = Turing as a runner | url = http://www-groups.dcs.st-and.ac.uk/~history/Extras/Turing_running.html | publisher = The MacTutor History of Mathematics archive | date = December 1999 | access-date = 12 June 2014 | archive-url = https://web.archive.org/web/20141113020916/http://www-groups.dcs.st-and.ac.uk/~history/Extras/Turing_running.html | archive-date = 13 November 2014 | url-status = live }}</ref> When asked why he ran so hard in training he replied:

{{blockquote|I have such a stressful job that the only way I can get it out of my mind is by running hard; it's the only way I can get some release.<ref>{{cite web |url=https://kottke.org/18/04/alan-turing-was-an-excellent-runner |first=Jason |last=Kottke |title=Turing was an excellent runner |website=kottke.org |date=17 April 2018 |access-date=26 August 2024 |archive-date=9 June 2021 |archive-url=https://web.archive.org/web/20210609192748/https://kottke.org/18/04/alan-turing-was-an-excellent-runner |url-status=live }}</ref>}}

Due to the problems of [[counterfactual history]], it is hard to estimate the precise effect Ultra intelligence had on the war.<ref>See for example {{cite book|last=Richelson|first=Jeffery T.|title=A Century of Spies: Intelligence in the Twentieth Century|date=1997|publisher=Oxford University Press|location=New York|page=296|author-link=Jeffrey T. Richelson}} and {{cite book|last=Hartcup|first=Guy|title=The Effect of Science on the Second World War|date=2000|publisher=Macmillan Press|location=Basingstoke, Hampshire|pages=96–99|author-link=Guy Hartcup}}</ref> However, official war historian [[Harry Hinsley]] estimated that this work shortened the war in Europe by more than two years and saved over 14&nbsp;million lives.<ref name="Hinsley 1996">{{citation | last = Hinsley | first = Harry | author-link = Harry Hinsley | title = The Influence of ULTRA in the Second World War | origyear = 1993 | year = 1996 | url = http://www.cix.co.uk/~klockstone/hinsley.htm | access-date = 26 August 2024 | archive-date = 15 October 2022 | archive-url = https://web.archive.org/web/20221015210957/https://www.cix.co.uk/~klockstone/hinsley.htm | url-status = live }} Transcript of a lecture given on Tuesday 19 October 1993 at Cambridge University</ref>

[[File:Bombe-rebuild.jpg|thumbnail|right|A working replica of a [[bombe]] now at [[The National Museum of Computing]] on Bletchley Park]]The bombe searched for possible correct settings used for an Enigma message (i.e., rotor order, rotor settings and plugboard settings) using a suitable ''[[crib (cryptanalysis)|crib]]'': a fragment of probable [[plaintext]]. For each possible setting of the rotors (which had on the order of 10¹⁹ states, or 10²² states for the four-rotor U-boat variant),<ref>Jack Good in "The Men Who Cracked Enigma", 2003: with his caveat: "if my memory is correct".</ref> the bombe performed a chain of logical deductions based on the crib, implemented [[Electromechanics|electromechanically]].<ref>{{cite web |url=https://www.tnmoc.org/bombe |title=The Turing-Welchman Bombe |website=The National Museum of Computing |access-date=18 March 2021 |archive-date=24 January 2022 |archive-url=https://web.archive.org/web/20220124200142/https://www.tnmoc.org/bombe |url-status=live }}</ref>

Turing travelled to the United States in November 1942 and worked with US Navy cryptanalysts on the naval Enigma and bombe construction in Washington.<ref>{{Harvnb|Hodges|1983|pp=242–245}}</ref><ref>{{Cite web |title=Alan Turing's Report from Washington, 1942 |url=https://www.turing.org.uk/sources/washington.html |access-date=12 July 2023 |website=www.turing.org.uk |archive-07-date=12 July 2023 |websitearchive-url=https://web.archive.org/web/20230712083844/https://www.turing.org.uk/sources/washington.html |url-status=live }}</ref> He also visited their [[United States Naval Computing Machine Laboratory|Computing Machine Laboratory]] in [[Dayton, Ohio]].<ref>{{Cite web |title=Alan Turing's Dayton Report, 1942 |url=https://www.turing.org.uk/sources/dayton123.html |access-date=2023-07-12 July 2023 |website=www.turing.org.uk}}</ref>

Following his work at [[Bell Labs]] in the US,<ref>{{Harvnb|Hodges|1983|pp=245–250}}</ref> Turing pursued the idea of electronic enciphering of speech in the telephone system. In the latter part of the war, he moved to work for the Secret Service's Radio Security Service (later [[Her Majesty's Government Communications Centre|HMGCC]]) at [[Hanslope Park]].<ref>{{cite journal| last = Harper| first = John| author-link = John Harper (computer engineer)| title = Delilah Voice Secrecy System| journal = Resurrection: The Journal of the Computer Conservation Society| issue = 101| pages = 8–9| publisher = The Computer Conservation Society| date = Spring 2023| url = https://www.computerconservationsociety.org/resurrection/res101.htm#d| access-date = 28 June 2023}}</ref><ref>{{cite journal| last = Harper| first = John| author-link = John Harper (computer engineer)| title = Delilah Voice Secrecy System [part 2]: The Design, Development and Commissioning of Delilah in 1943 – 1945| journal = Resurrection: The Journal of the Computer Conservation Society| issue = 102| pages = 16–19| publisher = The Computer Conservation Society| date = Summer 2023| url = https://www.computerconservationsociety.org/resurrection/res102.htm#c| access-date = 28 June 2023| archive-date = 3 July 2023| archive-url = https://web.archive.org/web/20230703233634/https://www.computerconservationsociety.org/resurrection/res102.htm#c| url-status = live}}</ref> At the park, he further developed his knowledge of electronics with the assistance of [[Royal Electrical and Mechanical Engineers|REME]] officer Donald Bayley. Together they undertook the design and construction of a portable [[secure voice]] communications machine codenamed ''[[Delilah (voice encryption)|Delilah]]''.<ref>{{Harvnb|Hodges|1983|p=273}}</ref> The machine was intended for different applications, but it lacked the capability for use with long-distance radio transmissions. In any case, Delilah was completed too late to be used during the war. Though the system worked fully, with Turing demonstrating it to officials by encrypting and decrypting a recording of a [[Winston Churchill]] speech, Delilah was not adopted for use.<ref>{{Harvnb|Hodges|1983|p=346}}</ref> Turing also consulted with Bell Labs on the development of [[SIGSALY]], a secure voice system that was used in the later years of the war.

In 1948, Turing was appointed [[Reader (academic rank)|reader]] in the [[School of Mathematics, University of Manchester|Mathematics Department]] at the [[Victoria University of Manchester]]. A year later, he became deputy director of the Computing Machine Laboratory, where he worked on software for one of the earliest [[Von Neumann architecture|stored-program]] computers—the [[Manchester Mark 1]]. Turing wrote the first version of the Programmer's Manual for this machine, and was recruited by Ferranti as a consultant in the development of their commercialised machine, the Ferranti Mark 1. He continued to be paid consultancy fees by Ferranti until his death.<ref>{{Cite book|url=https://www.manturing.net/|title=Alan Turing's Manchester|last=Swinton|first=Jonathan|publisher=Infang Publishing|year=2019|isbn=978-0-9931789-2-4|location=Manchester|access-date=18 March 2019|archive-url=https://web.archive.org/web/20190217172318/https://www.manturing.net/|archive-date=17 February 2019|url-status=live}}</ref> During this time, he continued to do more abstract work in mathematics,<ref name="doi10.1093/qjmam/1.1.287">{{Cite journal|last1 = Turing |first1 = A.M.|doi = 10.1093/qjmam/1.1.287 |title = Rounding-Off Errors in Matrix Processes |journal = The Quarterly Journal of Mechanics and Applied Mathematics |volume = 1| pages = 287–308 |year = 1948| issue=1 |hdl = 10338.dmlcz/103139|doi-access = free }}</ref> and in "[[Computing Machinery and Intelligence]]" (''[[Mind (journal)|Mind]]'', October 1950), Turing addressed the problem of [[artificial intelligence]], and proposed an experiment that became known as the [[Turing test]], an attempt to define a standard for a machine to be called "intelligent". The idea was that a computer could be said to "think" if a human interrogator could not tell it apart, through conversation, from a human being.<ref>{{Cite book |author-link=Stevan Harnad |last=Harnad |first=Stevan |year=2008 |chapter-url=http://eprints.soton.ac.uk/262954/ |chapter=The Annotation Game: On Turing (1950) on Computing, Machinery and Intelligence |archive-url=https://web.archive.org/web/20171018070225/https://eprints.soton.ac.uk/262954/ |archive-date=18 October 2017 |editor1-last=Epstein |editor1-first=Robert |editor2-last=Peters |editor2-first=Grace |title=Parsing the Turing Test: Philosophical and Methodological Issues in the Quest for the Thinking Computer |publisher=Springer|isbn=9781402067082 }}</ref> In the paper, Turing suggested that rather than building a program to simulate the adult mind, it would be better to produce a simpler one to simulate a child's mind and then to subject it to a course of education. A [[Turing test#Reverse Turing test and CAPTCHA|reversed]] form of the Turing test is widely used on the Internet; the [[CAPTCHA]] test is intended to determine whether the user is a human or a computer.

A study conducted in 2023 confirmed Turing's mathematical model hypothesis. Presented by the [[American Physical Society]], the experiment involved growing [[chia seed]]s in even layers within trays, later adjusting the available moisture. Researchers experimentally tweaked the factors which appear in the Turing equations, and, as a result, patterns resembling those seen in natural environments emerged. This is believed to be the first time that experiments with living vegetation have verified Turing's mathematical insight.<ref>{{cite news|url=https://www.sciencenews.org/article/seeds-alan-turing-patterns-nature-math|author=James R. Riordon|date=March 26, March 2023|title=Chia seedlings verify Alan Turing's ideas about patterns in nature|work=Science News|access-date=26 August 2024|archive-date=2 July 2024|archive-url=https://web.archive.org/web/20240702160511/https://www.sciencenews.org/article/seeds-alan-turing-patterns-nature-math|url-status=live}}</ref><ref>{{cite news|url=https://meetings.aps.org/Meeting/MAR23/Session/F46.3|author=Brendan D'Aquino|date=March 7, March 2023|title=Abstract: F46.00003 : Studying Turing patterns in vegetation|work=American Physical Society|access-date=26 August 2024|archive-date=2 July 2024|archive-url=https://web.archive.org/web/20240702162242/https://meetings.aps.org/Meeting/MAR23/Session/F46.3|url-status=live}}</ref>

In the 1940s, Turing became worried about losing his savings in the event of a German invasion. In order to protect it, he bought two [[Silver as an investment|silver bars]] weighing {{cvt|3200|oz|kg|-1}} and worth £250 (in 2022, £8,000 adjusted for inflation, £48,000 at spot price) and buried them in a wood near Bletchley Park.<ref>{{Cite book |last=Myrberg Burström |first=Nanouschka |url=https://www.academia.edu/13683478 |title=A tale of buried treasure, some good estimations, and golden unicorns: The numismatic connections of Alan Turing |publisher=Svenska Numismatiska Föreningen |year=2015 |isbn=9789197942720 |location=Stockholm |pages=226–230 |language=en |access-date=26 August 2024 |archive-date=2 July 2024 |archive-url=https://web.archive.org/web/20240702161450/https://www.academia.edu/13683478 |url-status=live }}</ref> Upon returning to dig them up, Turing found that he was unable to break his own code describing where exactly he had hidden them. This, along with the fact that the area had been renovated, meant that he never regained the silver.<ref>{{Cite book |last=Hodges |first=Andrew |title=Alan Turing: the enigma |publisher=Princeton University Press |year=2014 |isbn=9780691164724 |location=United States of America |pages=643 |language=en}}</ref>

In January 1952, Turing was 39 when he started a relationship withmet Arnold Murray, a 19-year-old unemployed man. The two agreed to meet again and in 1952 began an intimate relationship.<ref>{{Cite web |title=Alan Turing |url=https://spartacus-educational.com/Alan_Turing.htm |access-date=2023-07-22 July 2023 |website=Spartacus Educational |language=en |archive-date=25 November 2021 |archive-url=https://web.archive.org/web/20211125054932/https://spartacus-educational.com/Alan_Turing.htm |url-status=live }}</ref> Just before Christmas, Turing was walking along Manchester's [[Wilmslow Road|Oxford Road]] when he met Murray just outside the [[Dancehouse|Regal Cinema]] and invited him to lunch. On 23 January, Turing's house was burgled. Murray told Turing that he and the burglar were acquainted, and Turing reported the crime to the police. During the investigation, he acknowledged a sexual relationship with Murray. Homosexual acts were criminal offences in the United Kingdom at that time,<ref>{{Harvnb|Hodges|1983|p=458}}</ref> and both men were charged with "[[gross indecency]]" under [[Criminal Law Amendment Act 1885#Section 11|Section 11]] of the [[Criminal Law Amendment Act 1885]].<ref name="LeavittP268">{{Harvnb|Leavitt|2007|p=268}}</ref> Initial [[committal procedure|committal proceedings]] for the trial were held on 27 February during which Turing's solicitor "reserved his defence", i.e., did not argue or provide evidence against the allegations. The proceedings were held at the [[Sessions House, Knutsford|Sessions House]] in [[Knutsford]].<ref>{{Cite news|url= https://www.manchestereveningnews.co.uk/news/nostalgia/historic-courthouse-near-manchester-famous-26261769 |title= Historic courthouse near Manchester where famous trial took place unrecognisable after stunning renovation|date=20 February 2023|newspaper=Manchester Evenings News| access-date=5 April 2023|archive-date=5 April 2023|archive-url=https://web.archive.org/web/20230405175213/https://www.manchestereveningnews.co.uk/news/nostalgia/historic-courthouse-near-manchester-famous-26261769|url-status=live}}</ref>

Turing was later convinced by the advice of his brother and his own solicitor, and he entered a plea of guilty.<ref>{{cite book |title=Alan Turing: The Enigma |publisher=Princeton University Press |author-link=Andrew Hodges |last=Hodges |first=Andrew |page=[https://archive.org/details/alanturingenigma0000hodg/page/463 463] |year=2012 |isbn=978-0-691-15564-7 |url=https://archive.org/details/alanturingenigma0000hodg|url-access=registration }}</ref> The case, ''[[Elizabeth II|Regina]] v. Turing and Murray,'' was brought to trial on 31 March 1952.<ref>{{cite book |title=Alan Turing: The Enigma |publisher=Princeton University Press |author-link=Andrew Hodges |last=Hodges |first=Andrew |page=[https://archive.org/details/alanturingenigma0000hodg/page/471 471] |year=2012 |isbn=978-0-691-15564-7 |url=https://archive.org/details/alanturingenigma0000hodg|url-access=registration }}</ref> Turing was convicted and given a choice between imprisonment and probation. His probation would be conditional on his agreement to undergo [[hormone|hormonal]] physical changes designed to reduce [[libido]], known as "[[chemical castration]]".<ref name=":2">{{Cite journal |last=Peralta |first=René |date=23 June 2022 |title=Alan Turing's Everlasting Contributions to Computing, AI and Cryptography |url=https://www.nist.gov/blogs/taking-measure/alan-turings-everlasting-contributions-computing-ai-and-cryptography |journal=NIST |language=en |access-date=26 August 2024 |archive-date=23 August 2024 |archive-url=https://web.archive.org/web/20240823194432/https://www.nist.gov/blogs/taking-measure/alan-turings-everlasting-contributions-computing-ai-and-cryptography |url-status=live }}</ref> He accepted the option of injections of what was then called stilboestrol (now known as [[diethylstilbestrol]] or DES), a synthetic [[oestrogen]]; this feminization of his body was continued for the course of one year. The treatment rendered Turing [[impotence|impotent]] and caused [[gynaecomastia|breast tissue to form]].<ref>{{cite book | title=Alan Turing: The Enigma The Centenary Edition | publisher=Princeton University | author= Hodges, Andrew | year=2012}}</ref> In a letter, Turing wrote that "no doubt I shall emerge from it all a different man, but quite who I've not found out".<ref>{{cite web |title=Letters of Note: Yours in distress, Alan |last=Turing |first=Alan |year=1952 |url=http://www.lettersofnote.com/2012/06/yours-in-distress-alan.html |archive-date=20 January 2013 |archive-url=https://web.archive.org/web/20130120024901/http://www.lettersofnote.com/2012/06/yours-in-distress-alan.html |url-status=dead |access-date=16 December 2012 }}</ref><ref>{{cite book |title=Alan Turing: The Enigma |publisher=Princeton University Press |author-link=Andrew Hodges |last=Hodges |first=Andrew |page=xxviii |year= 2012 |isbn=978-0-691-15564-7 |url=https://archive.org/details/alanturingenigma0000hodg|url-access=registration }}</ref> Murray was given a conditional discharge.<ref>{{Harvnb|Hodges|1983|p=473}}</ref>

Turing's conviction led to the removal of his security clearance and barred him from continuing with his cryptographic consultancy for the [[Government Communications Headquarters]] (GCHQ), the British [[signals intelligence]] agency that had evolved from GC&CS in 1946, though he kept his academic job. His trial took place only months after the defection to the Soviet Union of [[Guy Burgess]] and [[Donald Maclean (spy)|Donald Maclean]] in summer 1951 after which the Foreign Office started to consider anyone known to be homosexual as a potential security risk.<ref>{{cite web|url=https://theconversation.com/revealed-the-panic-that-followed-the-defection-of-the-cambridge-spies-49623|title=The Panic that followed the defection of the Cambridge spies|website=The Conversation|date=23 October 2015 |access-date=12 August 2023|archive-date=13 August 2023|archive-url=https://web.archive.org/web/20230813085159/https://theconversation.com/revealed-the-panic-that-followed-the-defection-of-the-cambridge-spies-49623|url-status=live}}</ref>

===Death===

On 8 June 1954, at his house at 43 Adlington Road, [[Wilmslow]], Turing's housekeeper found him dead.<ref name=copperfolly>{{cite web|archive-url=https://web.archive.org/web/20210703105309/https://assets.savills.com/properties/GBWSRSWIS210139/WIS210139_WIS21003746.PDF|archive-date=3 July 2021|url=https://assets.savills.com/properties/GBWSRSWIS210139/WIS210139_WIS21003746.PDF|website=savills.com|author=Anon|year=2021|title=Turing's House: Copper Folly, 43 Adlington Road, Wilmslow, Cheshire, SK9 2BJ}}</ref> A post mortem was held that evening, which determined that he had died the previous day at the age of 41 with [[cyanide poisoning]] cited as the cause of death.<ref>{{cite web|url=https://turingarchive.kings.cam.ac.uk/material-given-kings-college-cambridge-1960-amtk/amt-k-6|title=Post Mortem Examination|website=Turing Digital Archive|access-date=26 August 2024|archive-date=15 July 2024|archive-url=https://web.archive.org/web/20240715235055/https://turingarchive.kings.cam.ac.uk/material-given-kings-college-cambridge-1960-amtk/amt-k-6|url-status=live}}</ref><ref>{{Cite encyclopedia |url=https://www.britannica.com/biography/Alan-Turing#toc330986 |title=Alan Turing. Biography, Facts, & Education |encyclopedia=Encyclopædia Britannica |access-date=11 October 2017 |archive-url=https://web.archive.org/web/20171011184445/https://www.britannica.com/biography/Alan-Turing#toc330986 |archive-date=11 October 2017 |url-status=live }}</ref> When his body was discovered, an apple lay half-eaten beside his bed, and although the apple was not tested for cyanide,<ref>{{Harvnb|Hodges|1983|p=488}}</ref> it was speculated that this was the means by which Turing had consumed a fatal dose.

Turing's brother, John, identified the body the following day and took the advice given by Dr. Greenbaum to accept the verdict of the [[Inquests in England and Wales|inquest]], as there was little prospect of establishing that the death was accidental.<ref name="reflections">{{cite book|title=Reflections of Alan Turing|last=Turing|first=Dermot|publisher=The History Press |year=2021 |isbn=9781803990125}}</ref> The [[Inquests in England and Wales|inquest]] was held the following day, which determined the cause of death to be suicide.<ref name=":2" /> Turing's remains were cremated at [[Woking Crematorium]] just two days later on 12 June 1954 with just three people attending<ref>{{cite book|title=Alan Turing: Guildford's best kept secret|last=Backhouse|first=Paul|publisher=Guildford Town Guides |year=2016}}</ref><ref>{{Harvnb|Hodges|1983|p=529}}</ref> and his ashes were scattered in the gardens of the crematorium, just as his father's had been.<ref name="hodges2012">{{cite book |url=https://books.google.com/books?id=EpAl0piM38cC |title=Alan Turing: The Enigma |last=Hodges |first=Andrew |date=2012 |publisher=Random House |isbn=978-1-4481-3781-7 |access-date=16 January 2019 |archive-url=https://web.archive.org/web/20190117070027/https://books.google.co.uk/books?id=EpAl0piM38cC |archive-date=17 January 2019 |url-status=live }}</ref> Turing's mother was on holiday in Italy at the time of his death and returned home after the inquest. She never accepted the verdict of suicide.<ref name=reflections/>

Philosopher [[Jack Copeland]] has questioned various aspects of the coroner's historical verdict. He suggested an alternative explanation for the cause of Turing's death: the accidental inhalation of cyanide fumes from an apparatus used tobiographer [[electroplating|electroplate]]Andrew gold onto spoons. The [[potassium cyanideHodges]] was used to [[Gold#Chemistry|dissolve the gold]]. Turing had such an apparatus set up in his tiny spare room. Copeland noted that the autopsy findings were more consistent with inhalation than with ingestion of the poison. Turing also habitually ate an apple before going to bed, and it was not unusual for the apple to be discarded half-eaten.<ref name = "Copeland">{{cite news | first = Roland | last = Pease | title = Alan Turing: Inquest's suicide verdict 'not supportable' | url = https://www.bbc.co.uk/news/science-environment-18561092 | work = [[BBC News]] | date = 23 June 2012 | access-date = 23 June 2012 | quote = We have&nbsp;... been recreating the narrative of Turing's life, and we have recreated him as an unhappy young man who committed suicide. But the evidence is not there. | archive-url = https://web.archive.org/web/20120623101625/http://www.bbc.co.uk/news/science-environment-18561092 | archive-date = 23 June 2012 | url-status = live }}</ref> Furthermore, Turing had reportedly borne his legal setbacks and hormone treatment (which had been discontinued a year previously) "with good humour" and had shown no sign of despondency before his death. He even set down a list of tasks that he intended to complete upon returning to his office after the holiday weekend.<ref name = "Copeland"/> Turing's mother believed that the ingestion was accidental, resulting from her son's careless storage of laboratory chemicals.<ref>{{cite web |url=https://www.christies.com/lotfinder/lot_details.aspx?intObjectID=5685694 |title=TURING, Ethel Sara (1881–1976, mother of Alan Turing). Series of 11 autograph letters to Robin Gandy, Guilford, 28 July 1954 – 11 June 1971 (most before 1959), altogether 29 pages, 8vo (2 letters dated 17 May and 26 May 1955 incomplete, lacking continuation leaves, occasional light soiling) |website=christies.com |access-date=6 February 2019 |archive-url=https://web.archive.org/web/20190207015923/https://www.christies.com/lotfinder/lot_details.aspx?intObjectID=5685694 |archive-date=7 February 2019 |url-status=live }}</ref> Biographer Andrew Hodges theorised that Turing deliberately left the nature of his death ambiguous in order to shield his mother from the knowledge that he had killed himself.<ref>{{Harvnb|Hodges|1983|pp=488, 489}}</ref> Doubts on the suicide thesis have been also cast by [[John W. Dawson Jr.]] who, in his review of Hodges' book, recalls "Turing's vulnerable position in the Cold War political climate" and points out that "Turing was found dead by a maid, who discovered him 'lying neatly in his bed'—hardly what one would expect of "a man fighting for life against the suffocation induced by cyanide poisoning." Turing had given no hint of suicidal inclinations to his friends and had made no effort to put his affairs in order.<ref>{{cite journal |last= Dawson Jr. |first=John W. |author-link=John W. Dawson Jr. |title="Review of Andrew Hodges. Alan Turing: the enigma" |journal=[[Journal of Symbolic Logic]] |volume=50 |issue=4 |date=December 1985 |pages=1065–1067 |doi=10.2307/2273992 |jstor=2273992 |url=https://doi.org/10.2307/2273992}}</ref>

John Leech, the MP for [[Manchester Withington (UK Parliament constituency)|Manchester Withington]] (2005–15), submitted several bills to Parliament<ref>{{cite web|url=http://www.politics.co.uk/news/2013/12/24/better-late-than-never-alan-turing-is-finally-pardoned|title=Better late than never, Alan Turing is finally pardoned|first=Alex|last=Stevenson|date=24 December 2013|publisher=politics.co.uk|access-date=25 September 2016|archive-url=https://web.archive.org/web/20160816015157/http://www.politics.co.uk/news/2013/12/24/better-late-than-never-alan-turing-is-finally-pardoned|archive-date=16 August 2016|url-status=live}}</ref> and led a high-profile campaign to secure the pardon. Leech made the case in the House of Commons that Turing's contribution to the war made him a national hero and that it was "ultimately just embarrassing" that the conviction still stood.<ref name="Fitzgerald">{{cite web|url=http://www.manchestereveningnews.co.uk/news/greater-manchester-news/alan-turings-court-convictions-go-11931942|title=Alan Turing's court convictions go on display for the first time|first=Todd|last=Fitzgerald|date=24 September 2016|publisher=manchestereveningnews.co.uk|access-date=25 September 2016|archive-url=https://web.archive.org/web/20160925151625/http://www.manchestereveningnews.co.uk/news/greater-manchester-news/alan-turings-court-convictions-go-11931942|archive-date=25 September 2016|url-status=live}}</ref> Leech continued to take the bill through Parliament and campaigned for several years, gaining the public support of numerous leading scientists, including [[Stephen Hawking]].<ref>{{Cite news|url=https://www.manchestereveningnews.co.uk/news/greater-manchester-news/manchester-codebreaker-alan-turing-pardoned-6442836|title=Alan Turing pardoned by The Queen for his 'unjust and discriminatory' conviction for homosexuality|last=Britton|first=Paul|work=Manchester Evening News|date=24 December 2013|access-date=24 June 2018|archive-url=https://web.archive.org/web/20180624204418/https://www.manchestereveningnews.co.uk/news/greater-manchester-news/manchester-codebreaker-alan-turing-pardoned-6442836|archive-date=24 June 2018|url-status=live}}</ref><ref>{{cite news|url=https://www.bbc.co.uk/news/uk-england-manchester-16833621|title=MP calls for pardon for computer pioneer Alan Turing|date=1 February 2012|work=BBC News|access-date=25 September 2016|archive-url=https://web.archive.org/web/20160702135251/http://www.bbc.co.uk/news/uk-england-manchester-16833621|archive-date=2 July 2016|url-status=live}}</ref> At the British premiere of a film based on Turing's life, ''[[The Imitation Game]]'', the producers thanked Leech for bringing the topic to public attention and securing Turing's pardon.<ref>{{Cite news|url=https://www.libdemvoice.org/my-proudest-day-as-a-liberal-democrat-43430.html|title=My proudest day as a Liberal Democrat|work=Liberal Democrat Voice|access-date=24 June 2018|archive-url=https://web.archive.org/web/20180624204354/https://www.libdemvoice.org/my-proudest-day-as-a-liberal-democrat-43430.html|archive-date=24 June 2018|url-status=live}}</ref> Leech is now regularly described as the "architect" of Turing's pardon and subsequently the Alan Turing Law which went on to secure pardons for 75,000 other men and women convicted of similar crimes.<ref>{{Cite web |url=https://www.manchestereveningnews.co.uk/news/greater-manchester-news/manchester-computer-pioneer-alan-turing-16585966 |title=Manchester computer pioneer Alan Turing announced as face of new £50 note |date=15 July 2019 |access-date=19 July 2019 |archive-url=https://web.archive.org/web/20190719082039/https://www.manchestereveningnews.co.uk/news/greater-manchester-news/manchester-computer-pioneer-alan-turing-16585966 |archive-date=19 July 2019 |url-status=live }}</ref><ref>{{Cite web|url=http://outnewsglobal.com/john-leech-secures-historic-deal-with-government-on-alan-turing-law/|title=John Leech secures historic deal with Government on 'Alan Turing Law'|date=20 October 2016|website=outnewsglobal.com|access-date=26 August 2024|archive-date=29 January 2022|archive-url=https://web.archive.org/web/20220129031439/http://outnewsglobal.com/john-leech-secures-historic-deal-with-government-on-alan-turing-law/|url-status=live}}</ref><ref>{{Cite news|url=https://www.theguardian.com/business/2019/jul/15/alan-turing-to-feature-on-new-50-note|title=Alan Turing to feature on new £50 banknote|newspaper=The Guardian |editor1-first=Larry|editor1-last=Elliott|editor2-first=Josh|editor2-last=Halliday|date=15 July 2019|via=www.theguardian.com|access-date=26 August 2024|archive-date=29 January 2022|archive-url=https://web.archive.org/web/20220129025950/https://www.theguardian.com/business/2019/jul/15/alan-turing-to-feature-on-new-50-note|url-status=live}}</ref><ref>{{Cite web|url=http://www.mirror.co.uk/news/uk-news/tory-minister-refuses-apologise-killing-9108424|title=Tory refuses to apologise for 'killing bad law' pardoning thousands of gay men|first=Dan|last=Bloom|date=23 October 2016|website=mirror|access-date=26 August 2024|archive-date=29 January 2022|archive-url=https://web.archive.org/web/20220129030015/https://www.mirror.co.uk/news/uk-news/tory-minister-refuses-apologise-killing-9108424|url-status=live}}</ref><ref>{{Cite web|url=https://www.dunfermlinepress.com/news/national-news/17771381.alan-turings-fearless-approach-problems-intellectual-curiosity-praised/|title=Alan Turing's 'fearless approach to problems and intellectual curiosity' praised|website=Dunfermline Press|date=15 July 2019|access-date=26 August 2024|archive-date=29 January 2022|archive-url=https://web.archive.org/web/20220129030030/https://www.dunfermlinepress.com/news/national-news/17771381.alan-turings-fearless-approach-problems-intellectual-curiosity-praised/|url-status=live}}</ref><ref>{{Cite web|url=https://thetab.com/uk/manchester/2017/01/31/alan-turing-law-finally-pardons-thousands-unfairly-convicted-25615|title=The Alan Turing Law finally pardons thousands of unfairly convicted gay and bisexual men|date=31 January 2017|website=University of Manchester|access-date=26 August 2024|archive-date=29 January 2022|archive-url=https://web.archive.org/web/20220129025935/https://thetab.com/uk/manchester/2017/01/31/alan-turing-law-finally-pardons-thousands-unfairly-convicted-25615|url-status=live}}</ref><ref>{{Cite web|url=https://qnews.com.au/bank-of-england-honours-alan-turing-on-50-note/|title=Bank of England honours Alan Turing on £50 note|date=15 July 2019|website=QNews|access-date=26 August 2024|archive-date=29 January 2022|archive-url=https://web.archive.org/web/20220129031411/https://qnews.com.au/bank-of-england-honours-alan-turing-on-50-note/|url-status=live}}</ref>

On 26 July 2012, a bill was introduced in the [[British House of Lords|House of Lords]] to grant a statutory pardon to Turing for offences under section 11 of the Criminal Law Amendment Act 1885, of which he was convicted on 31 March 1952.<ref>{{cite web |url=http://services.parliament.uk/bills/2012-13/alanturingstatutorypardon.html |title=Bill |publisher=Parliament of the United Kingdom |date=26 July 2012 |access-date=31 October 2013 |archive-url=https://web.archive.org/web/20131102040318/http://services.parliament.uk/bills/2012-13/alanturingstatutorypardon.html |archive-date=2 November 2013 |url-status=live }}</ref> Late in the year in a letter to ''[[The Daily Telegraph]]'', the physicist Stephen Hawking and 10 other signatories including the [[Astronomer Royal]] [[Martin Rees, Baron Rees of Ludlow|Lord Rees]], [[List of presidents of the Royal Society|President of the Royal Society]] Sir [[Paul Nurse]], [[Jean Barker, Baroness Trumpington|Lady Trumpington]] (who worked for Turing during the war) and [[John Sharkey, Baron Sharkey|Lord Sharkey]] (the bill's sponsor) called on Prime Minister [[David Cameron]] to act on the pardon request.<ref>{{Cite news |last=Pearse |first=Damian |url=https://www.theguardian.com/science/2012/dec/14/alan-turing-pardon-stephen-hawking |title=Alan Turing should be pardoned, argue Stephen Hawking and top scientists |archive-url=https://web.archive.org/web/20170204090812/https://www.theguardian.com/science/2012/dec/14/alan-turing-pardon-stephen-hawking |archive-date=4 February 2017 |work=The Guardian |date=13 December 2012 |access-date=15 December 2012}}</ref> The government indicated it would support the bill,<ref name=turingguardian19july2013>{{cite news|url=https://www.theguardian.com/uk-news/2013/jul/19/enigma-codebreaker-alan-turing-posthumous-pardon|title=Enigma codebreaker Alan Turing to be given posthumous pardon|work=The Guardian|date=19 July 2013|author=Watt, Nicholas|location=London|access-date=10 December 2016|archive-url=https://web.archive.org/web/20170104124001/https://www.theguardian.com/uk-news/2013/jul/19/enigma-codebreaker-alan-turing-posthumous-pardon|archive-date=4 January 2017|url-status=live}}</ref><ref>{{cite news|url=http://www.v3.co.uk/v3-uk/news/2302744/alan-turing-pardon-moves-a-step-closer|title=Alan Turing pardon sails through House of Lords|last=Worth|first=Dan|date=30 October 2013|publisher=V3|access-date=24 December 2013|archive-url=https://web.archive.org/web/20131224114746/http://www.v3.co.uk/v3-uk/news/2302744/alan-turing-pardon-moves-a-step-closer|archive-date=24 December 2013|url-status=live}}</ref><ref>{{cite web | title =Alan Turing (Statutory Pardon) Bill | url =http://services.parliament.uk/bills/2013-14/alanturingstatutorypardon.html | access-date =20 July 2013 | archive-url =https://web.archive.org/web/20130705084023/http://services.parliament.uk/bills/2013-14/alanturingstatutorypardon.html | archive-date =5 July 2013 | url-status =live }}</ref> and it passed its third reading in the House of Lords in October.<ref name=turingpinknewsdec2013>{{cite news|url=http://www.pinknews.co.uk/2013/12/02/lib-dem-mp-john-leech-disappointed-at-delay-to-alan-turing-pardon-bill|title=Lib Dem MP John Leech disappointed at delay to Alan Turing pardon bill|newspaper=Pink News|date=2 December 2013|author=Roberts, Scott|access-date=24 December 2013|archive-url=https://web.archive.org/web/20131225050250/http://www.pinknews.co.uk/2013/12/02/lib-dem-mp-john-leech-disappointed-at-delay-to-alan-turing-pardon-bill|archive-date=25 December 2013|url-status=live}}</ref>

On 19 July 2023, [[Sexual orientation and the military of the United Kingdom#Official apology to veterans|following an apology to LGBT veterans from the UK Government]], [[Secretary of State for Defence|Defence Secretary]] [[Ben Wallace (politician)|Ben Wallace]] suggested Turing should be honoured with a permanent statue on the [[Fourth plinth#Proposals for permanent statues|fourth plinth of Trafalgar Square]], describing Dr Turing as "probably the greatest war hero, in my book, of the Second World War, [whose] achievements shortened the war, saved thousands of lives, helped defeat the Nazis. And his story is a sad story of a society and how it treated him."<ref>{{Cite web |title=Veterans Update |url=https://hansard.parliament.uk/Commons/2023-07-19/debates/56A50AFF-35D8-408F-A393-DDB38951E64F/VeteransUpdate?#contribution-43233FDB-224B-4D71-B796-BB90C501DB16 |website=Hansard – UK Parliament |access-date=24 July 2023 |archive-date=24 July 2023 |archive-url=https://web.archive.org/web/20230724123630/https://hansard.parliament.uk/Commons/2023-07-19/debates/56A50AFF-35D8-408F-A393-DDB38951E64F/VeteransUpdate#contribution-43233FDB-224B-4D71-B796-BB90C501DB16 |url-status=live }}</ref><ref>{{Cite news |title=Alan Turing statue should be put on Trafalgar Square's fourth plinth, says Ben Wallace |url=https://www.telegraph.co.uk/politics/2023/07/19/alan-turing-trafalgar-square-fourth-plinth-ben-wallace/ |website=The Telegraph |date=19 July 2023 |access-date=24 July 2023 |last1=Sheridan |first1=Danielle |archive-date=24 July 2023 |archive-url=https://web.archive.org/web/20230724123628/https://www.telegraph.co.uk/politics/2023/07/19/alan-turing-trafalgar-square-fourth-plinth-ben-wallace/ |url-status=live }}</ref><ref>{{Cite news |title=LGBTQ+ military charity backs proposal for Alan Turing statue on fourth plinth |url=https://www.theguardian.com/science/2023/jul/24/lgbtq-military-charity-backs-proposal-alan-turing-statue-fourth-plinth-trafalgar-square |website=The Guardian |date=24 July 2023 |access-date=24 July 2023 |last1=Khomami |first1=Nadia |last2=Arts |first2=Nadia Khomami }}</ref>

* {{Cite journal | last = Turing | first = A. M. | publication-date = 1937 | title = On Computable Numbers, with an Application to the Entscheidungsproblem: A correction | periodical = Proceedings of the London Mathematical Society | series = 2 | volume = 43 | pages = 544–46 | doi = 10.1112/plms/s2-43.6.544 | year = 1938 | issue = 1 }}

* {{Cite web | last = Alexander | first = C. Hugh O'D. | title = Cryptographic History of Work on the German Naval Enigma | url = http://www.ellsbury.com/gne/gne-000.htm | publisher = The National Archives, Kew, Reference HW 25/1 | ref = {{harvid|Alexander|circa 1945}} | access-date = 15 November 2010 | archive-date = 17 February 2022 | archive-url = https://web.archive.org/web/20220217145825/http://www.ellsbury.com/gne/gne-000.htm | url-status = live }}

* {{cite book |last=Beavers |first=Anthony |editor1-first=S. Barry |editor1-last=Cooper |editor2-first=Jan |editor2-last=van Leeuwen |title=Alan Turing: His Work and Impact |publisher=Elsevier |location=Waltham |year=2013 |pages=481–485 |chapter=Alan Turing: Mathematical Mechanist |isbn=978-0-12-386980-7 |chapter-url=https://books.google.com/books?id=C9WQbm4ovFoC&pg=PA481 }}

* {{Cite web | last = Mahon | first = A. P. | title = The History of Hut Eight 1939–1945 | publisher = UK National Archives Reference HW 25/2 | year = 1945 | url = http://www.ellsbury.com/hut8/hut8-000.htm | access-date = 10 December 2009 | archive-date = 9 February 2022 | archive-url = https://web.archive.org/web/20220209012625/http://www.ellsbury.com/hut8/hut8-000.htm | url-status = live }}

* {{Cite news | last = Turing | first = A. M. | year = 1937 | title = On Computable Numbers, with an Application to the Entscheidungsproblem | orig-year = Delivered to the Society November 1936 | periodical = Proceedings of the London Mathematical Society | series = 2 | volume = 42 | issue = 1 | pages = 230–65 | doi = 10.1112/plms/s2-42.1.230 | url = http://www.comlab.ox.ac.uk/activities/ieg/e-library/sources/tp2-ie.pdf | access-date = 15 July 2009 | archive-date = 6 May 2011 | archive-url = https://web.archive.org/web/20110506090827/http://www.comlab.ox.ac.uk/activities/ieg/e-library/sources/tp2-ie.pdf | url-status = live }}

* {{cite journal| |title=The Mind and the Computing Machine: Alan Turing and others |journal=[[The Rutherford Journal]] |url=http://www.rutherfordjournal.org/article010111.html |editor-first=B. Jack | editor-last=Copeland | editor-link=Jack Copeland |access-date=6 April 2009 |archive-date=18 March 2012 |archive-url=https://web.archive.org/web/20120318165042/http://www.rutherfordjournal.org/article010111.html |url-status=live }}

* {{cite journal| |title=Alan Turing: Father of the Modern Computer |journal=[[The Rutherford Journal]] |url=http://www.rutherfordjournal.org/article040101.html |editor-first=B. Jack | editor-last=Copeland |access-date=19 November 2013 |archive-date=24 January 2022 |archive-url=https://web.archive.org/web/20220124221719/http://rutherfordjournal.org/article040101.html |url-status=live }}

* {{cite encyclopaedia |last=Hodges |first=Andrew |editor=Edward N. Zalta |encyclopedia=[[Stanford Encyclopedia of Philosophy]] |title=Alan Turing |url=http://plato.stanford.edu/entries/turing/ |access-date=10 January 2011 |edition=Winter 2009 |year=2007 |publisher=[[Stanford University]] }}

[[Category:20th-century English LGBTLGBTQ people]]

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[[Category:EnglishLGBTQ-related LGBT scientistssuicides]]

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