Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
Alan Turing

Alan Turing

Overview
Alan Mathison Turing, OBE
Order of the British Empire
The Most Excellent Order of the British Empire is an order of chivalry established on 4 June 1917 by George V of the United Kingdom. The Order comprises five classes in civil and military divisions...

, FRS (icon ; 23 June 1912 – 7 June 1954), was an English mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

, logician, cryptanalyst, and computer scientist
Computer scientist
A computer scientist is a scientist who has acquired knowledge of computer science, the study of the theoretical foundations of information and computation and their application in computer systems....

. He was highly influential in the development of computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...

, providing a formalisation of the concepts of "algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

" and "computation" with the Turing machine
Turing machine
A Turing machine is a theoretical device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a...

, which played a significant role in the creation of the modern computer. Turing is widely considered to be the father of computer science and artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

. He was stockily built, had a high-pitched voice, and was talkative, witty, and somewhat donnish
University don
A don is a fellow or tutor of a college or university, especially traditional collegiate universities such as Oxford and Cambridge in England.The term — similar to the title still used for Catholic priests — is a historical remnant of Oxford and Cambridge having started as ecclesiastical...

.

During the Second World War
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, Turing worked for the Government Code and Cypher School at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...

, Britain's codebreaking
Cryptanalysis
Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...

 centre.
Discussion
Ask a question about 'Alan Turing'
Start a new discussion about 'Alan Turing'
Answer questions from other users
Full Discussion Forum
 
Recent Discussions
Quotations

A man provided with paper, pencil, and rubber, and subject to strict discipline, is in effect a Turing machine|universal machine.

"Intelligent Machinery: A Report by A. M. Turing," (Summer 1948), submitted to the National Physical Laboratory (1948) and published in Key Papers: Cybernetics, ed. C. R. Evans and A. D. J. Robertson (1968) and, in variant form, in Machine Intelligence 5, ed. B. Meltzer and D. Michie (1969)

The idea behind digital computers may be explained by saying that these machines are intended to carry out any operations which could be done by a human computer.

p. 436

I believe that at the end of the century the use of words and general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted.

p. 442

I am not very impressed with theological arguments whatever they may be used to support. Such arguments have often been found unsatisfactory in the past. In the time of Galileo Galilei|Galileo it was argued that the texts, "And the sun stood still... and hasted not to go down about a whole day" (Joshua x. 13) and "He laid the foundations of the earth, that it should not move at any time" (Psalm cv. 5) were an adequate refutation of the Copernican theory.

pp. 443-444

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

p. 460
Encyclopedia
Alan Mathison Turing, OBE
Order of the British Empire
The Most Excellent Order of the British Empire is an order of chivalry established on 4 June 1917 by George V of the United Kingdom. The Order comprises five classes in civil and military divisions...

, FRS (icon ; 23 June 1912 – 7 June 1954), was an English mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

, logician, cryptanalyst, and computer scientist
Computer scientist
A computer scientist is a scientist who has acquired knowledge of computer science, the study of the theoretical foundations of information and computation and their application in computer systems....

. He was highly influential in the development of computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...

, providing a formalisation of the concepts of "algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

" and "computation" with the Turing machine
Turing machine
A Turing machine is a theoretical device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a...

, which played a significant role in the creation of the modern computer. Turing is widely considered to be the father of computer science and artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

. He was stockily built, had a high-pitched voice, and was talkative, witty, and somewhat donnish
University don
A don is a fellow or tutor of a college or university, especially traditional collegiate universities such as Oxford and Cambridge in England.The term — similar to the title still used for Catholic priests — is a historical remnant of Oxford and Cambridge having started as ecclesiastical...

.

During the Second World War
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, Turing worked for the Government Code and Cypher School at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...

, Britain's codebreaking
Cryptanalysis
Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...

 centre. For a time he was head of Hut 8
Hut 8
Hut 8 was a section at Bletchley Park tasked with solving German naval Enigma messages. The section was led initially by Alan Turing...

, the section responsible for German naval cryptanalysis
Cryptanalysis
Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...

. He devised a number of techniques for breaking German cipher
Cipher
In cryptography, a cipher is an algorithm for performing encryption or decryption — a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. In non-technical usage, a “cipher” is the same thing as a “code”; however, the concepts...

s, including the method of the bombe
Bombe
The bombe was an electromechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted signals during World War II...

, an electromechanical
Electromechanics
In engineering, electromechanics combines the sciences of electromagnetism, of electrical engineering and mechanics. Mechanical engineering in this context refers to the larger discipline which includes chemical engineering, and other related disciplines. Electrical engineering in this context...

 machine that could find settings for the Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...

. After the war he worked at the National Physical Laboratory
National Physical Laboratory, UK
The National Physical Laboratory is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, London, England. It is the largest applied physics organisation in the UK.-Description:...

, where he created one of the first designs for a stored-program computer, the ACE.

In 1948 Turing joined Max Newman's
Max Newman
Maxwell Herman Alexander "Max" Newman, FRS was a British mathematician and codebreaker.-Pre–World War II:Max Newman was born Maxwell Neumann in Chelsea, London, England, on 7 February 1897...

 Computing Laboratory at Manchester University
Victoria University of Manchester
The Victoria University of Manchester was a university in Manchester, England. On 1 October 2004 it merged with the University of Manchester Institute of Science and Technology to form a new entity, "The University of Manchester".-1851 - 1951:The University was founded in 1851 as Owens College,...

, where he assisted in the development of the Manchester computers
Manchester computers
The Manchester computers were an innovative series of stored-program electronic computers developed during the 30-year period between 1947 and 1977 by a small team at the University of Manchester, under the leadership of Tom Kilburn...

 and became interested in mathematical biology
Mathematical biology
Mathematical and theoretical biology is an interdisciplinary scientific research field with a range of applications in biology, medicine and biotechnology...

. He wrote a paper on the chemical basis of morphogenesis
Morphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...

, and he predicted oscillating
Chemical clock
A chemical clock is a complex mixture of reacting chemical compounds in which the concentration of one or more components exhibits periodic changes....

 chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

s such as the Belousov–Zhabotinsky reaction, which were first observed in the 1960s.

Turing's homosexuality
Homosexuality
Homosexuality is romantic or sexual attraction or behavior between members of the same sex or gender. As a sexual orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions" primarily or exclusively to people of the same...

 resulted in a criminal prosecution in 1952, when homosexual acts were still illegal in the United Kingdom. He accepted treatment with female hormones (chemical castration
Chemical castration
Chemical castration is the administration of medication designed to reduce libido and sexual activity, usually in the hope of preventing rapists, child molesters and other sex offenders from repeating their crimes...

) as an alternative to prison. He died in 1954, just over two weeks before his 42nd birthday, from cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....

 poisoning. An inquest determined it was suicide; his mother and some others believed his death was accidental. On 10 September 2009, following an Internet campaign, British Prime Minister
Prime Minister of the United Kingdom
The Prime Minister of the United Kingdom of Great Britain and Northern Ireland is the Head of Her Majesty's Government in the United Kingdom. The Prime Minister and Cabinet are collectively accountable for their policies and actions to the Sovereign, to Parliament, to their political party and...

 Gordon Brown
Gordon Brown
James Gordon Brown is a British Labour Party politician who was the Prime Minister of the United Kingdom and Leader of the Labour Party from 2007 until 2010. He previously served as Chancellor of the Exchequer in the Labour Government from 1997 to 2007...

 made an official public apology on behalf of the British government for the way in which Turing was treated after the war.

Childhood and youth


Alan Turing was conceived at Chhatrapur
Chhatrapur
Chhatrapur is a town and a notified area committee in Ganjam District in the state of Orissa, India. It is the headquarter town of Ganjam District. There are two railway stations in Chhatrapur. They are Chhatrapur station and Chhatrapur court station.-Geography:Chhatrapur is located at...

, Orissa
Orissa
Orissa , officially Odisha since Nov 2011, is a state of India, located on the east coast of India, by the Bay of Bengal. It is the modern name of the ancient nation of Kalinga, which was invaded by the Maurya Emperor Ashoka in 261 BC. The modern state of Orissa was established on 1 April...

, India
British Raj
British Raj was the British rule in the Indian subcontinent between 1858 and 1947; The term can also refer to the period of dominion...

. His father, Julius Mathison Turing, was a member of the Indian Civil Service. Julius and wife Ethel Sara Stoney (1881–1976, daughter of Edward Waller Stoney, chief engineer of the Madras Railways)
Madras and Southern Mahratta Railway
The Madras and Southern Mahratta Railway was a railway company that operated in southern India. It was founded on January 1, 1908, by merging the Madras Railway and the Southern Mahratta Railway. Initially, its headquarters was at Royapuram in Madras but later shifted to a newly constructed...

 wanted Alan to be brought up in England, so they returned to Maida Vale
Maida Vale
Maida Vale is a residential district in West London between St John's Wood and Kilburn. It is part of the City of Westminster. The area is mostly residential, and mainly affluent, consisting of many large late Victorian and Edwardian blocks of mansion flats...

, London, where Alan Turing was born on 23 June 1912, as recorded by a blue plaque
Blue plaque
A blue plaque is a permanent sign installed in a public place to commemorate a link between that location and a famous person or event, serving as a historical marker....

 on the outside of the building, later the Colonnade Hotel
Colonnade Hotel (London)
The Colonnade Hotel is a 4-star London hotel with 43 rooms, of which 3 are suites. The hotel is located opposite Warwick Avenue tube station and Little Venice.-History:...

. He had an elder brother, John. His father's civil service commission was still active, and during Turing's childhood years his parents travelled between Hastings
Hastings
Hastings is a town and borough in the county of East Sussex on the south coast of England. The town is located east of the county town of Lewes and south east of London, and has an estimated population of 86,900....

, England and India, leaving their two sons to stay with a retired Army couple. Very early in life, Turing showed signs of the genius he was to later prominently display.

His parents enrolled him at St Michael's, a day school at 20 Charles Road, St Leonards-on-Sea
St Leonards-on-Sea
St Leonards-on-Sea is part of Hastings, East Sussex, England, lying immediately to the west of the centre. The original part of the settlement was laid out in the early 19th century as a new town: a place of elegant houses designed for the well-off; it also included a central public garden, a...

, at the age of six. The headmistress recognised his talent early on, as did many of his subsequent educators. In 1926, at the age of 14, he went on to Sherborne School
Sherborne School
Sherborne School is a British independent school for boys, located in the town of Sherborne in north-west Dorset, England. It is one of the original member schools of the Headmasters' and Headmistresses' Conference....

, a famous independent school in the market town
Market town
Market town or market right is a legal term, originating in the medieval period, for a European settlement that has the right to host markets, distinguishing it from a village and city...

 of Sherborne
Sherborne
Sherborne is a market town in northwest Dorset, England. It is sited on the River Yeo, on the edge of the Blackmore Vale, east of Yeovil. The A30 road, which connects London to Penzance, runs through the town. The population of the town is 9,350 . 27.1% of the population is aged 65 or...

 in Dorset
Dorset
Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...

. His first day of term coincided with the 1926 General Strike
1926 United Kingdom general strike
The 1926 general strike in the United Kingdom was a general strike that lasted nine days, from 4 May 1926 to 13 May 1926. It was called by the general council of the Trades Union Congress in an unsuccessful attempt to force the British government to act to prevent wage reduction and worsening...

 in Britain, but so determined was he to attend his first day that he rode his bicycle unaccompanied more than 60 miles (96.6 km) from Southampton
Southampton
Southampton is the largest city in the county of Hampshire on the south coast of England, and is situated south-west of London and north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest...

 to school, stopping overnight at an inn.


Turing's natural inclination toward mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

 and science did not earn him respect with some of the teachers at Sherborne, whose definition of education placed more emphasis on the classics
Classics
Classics is the branch of the Humanities comprising the languages, literature, philosophy, history, art, archaeology and other culture of the ancient Mediterranean world ; especially Ancient Greece and Ancient Rome during Classical Antiquity Classics (sometimes encompassing Classical Studies or...

. His headmaster wrote to his parents: "I hope he will not fall between two stools. If he is to stay at Public School, he must aim at becoming educated. If he is to be solely a Scientific Specialist, he is wasting his time at a Public School". Despite this, Turing continued to show remarkable ability in the studies he loved, solving advanced problems in 1927 without having even studied elementary calculus
Calculus
Calculus is a branch of mathematics focused on limits, functions, derivatives, integrals, and infinite series. This subject constitutes a major part of modern mathematics education. It has two major branches, differential calculus and integral calculus, which are related by the fundamental theorem...

. In 1928, aged 16, Turing encountered Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

's work; not only did he grasp it, but he extrapolated Einstein's questioning of Newton's laws of motion
Newton's laws of motion
Newton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...

 from a text in which this was never made explicit.

Turing's hopes and ambitions at school were raised by the close friendship he developed with a slightly older fellow student, Christopher Morcom, who was Turing's first love interest. Morcom died on 13th February 1930suddenly, only a few weeks into their last term at Sherborne, from complications of bovine tuberculosis, contracted after drinking infected cow's milk as a boy. Turing's religious faith was shattered and he became an atheist. He adopted the conviction that all phenomena, including the workings of the human brain, must be materialistic
Materialism
In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena are the result of material interactions. In other words, matter is the only substance...

, but he still believed in the survival of the spirit after death.

University and work on computability



After Sherborne, Turing went to study at King's College, Cambridge
King's College, Cambridge
King's College is a constituent college of the University of Cambridge, England. The college's full name is "The King's College of our Lady and Saint Nicholas in Cambridge", but it is usually referred to simply as "King's" within the University....

. He was an undergraduate there from 1931 to 1934, graduating with first-class honours in Mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

, and in 1935 was elected a fellow
Fellow
A fellow in the broadest sense is someone who is an equal or a comrade. The term fellow is also used to describe a person, particularly by those in the upper social classes. It is most often used in an academic context: a fellow is often part of an elite group of learned people who are awarded...

 at King's on the strength of a dissertation on the central limit theorem
Central limit theorem
In probability theory, the central limit theorem states conditions under which the mean of a sufficiently large number of independent random variables, each with finite mean and variance, will be approximately normally distributed. The central limit theorem has a number of variants. In its common...

.

In 1928, German mathematician David Hilbert
David Hilbert
David Hilbert was a German mathematician. He is recognized as one of the most influential and universal mathematicians of the 19th and early 20th centuries. Hilbert discovered and developed a broad range of fundamental ideas in many areas, including invariant theory and the axiomatization of...

 had called attention to the Entscheidungsproblem
Entscheidungsproblem
In mathematics, the is a challenge posed by David Hilbert in 1928. The asks for an algorithm that will take as input a description of a formal language and a mathematical statement in the language and produce as output either "True" or "False" according to whether the statement is true or false...

(decision problem). In his momentous paper "On Computable Numbers, with an Application to the Entscheidungsproblem" (submitted on 28 May 1936 and delivered 12 November), Turing reformulated Kurt Gödel
Kurt Gödel
Kurt Friedrich Gödel was an Austrian logician, mathematician and philosopher. Later in his life he emigrated to the United States to escape the effects of World War II. One of the most significant logicians of all time, Gödel made an immense impact upon scientific and philosophical thinking in the...

's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with what became known as Turing machine
Turing machine
A Turing machine is a theoretical device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a...

s, formal and simple devices. He proved that some such machine would be capable of performing any conceivable mathematical computation if it were representable as an algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

. He went on to prove that there was no solution to the Entscheidungsproblem by first showing that the halting problem
Halting problem
In computability theory, the halting problem can be stated as follows: Given a description of a computer program, decide whether the program finishes running or continues to run forever...

 for Turing machines is undecidable
Decision problem
In computability theory and computational complexity theory, a decision problem is a question in some formal system with a yes-or-no answer, depending on the values of some input parameters. For example, the problem "given two numbers x and y, does x evenly divide y?" is a decision problem...

: it is not possible to decide, in general, algorithmically whether a given Turing machine will ever halt. While his proof was published subsequent to Alonzo Church's
Alonzo Church
Alonzo Church was an American mathematician and logician who made major contributions to mathematical logic and the foundations of theoretical computer science. He is best known for the lambda calculus, Church–Turing thesis, Frege–Church ontology, and the Church–Rosser theorem.-Life:Alonzo Church...

 equivalent proof in respect to his lambda calculus
Lambda calculus
In mathematical logic and computer science, lambda calculus, also written as λ-calculus, is a formal system for function definition, function application and recursion. The portion of lambda calculus relevant to computation is now called the untyped lambda calculus...

, Turing was unaware of Church's work at the time.

Turing's approach is considerably more accessible and intuitive. It was also novel in its notion of a 'Universal (Turing) Machine', the idea that such a machine could perform the tasks of any other machine, or in other words, is provably capable of computing anything that is computable. Turing machines are to this day a central object of study in theory of computation
Theory of computation
In theoretical computer science, the theory of computation is the branch that deals with whether and how efficiently problems can be solved on a model of computation, using an algorithm...

.

In his memoirs Turing wrote that he was disappointed about the reception of this 1936 paper and that only two people had reacted – these being Heinrich Scholz and Richard Bevan Braithwaite
R. B. Braithwaite
Richard Bevan Braithwaite was an English philosopher who specialized in the philosophy of science, ethics, and the philosophy of religion. He was a lecturer in moral science at the University of Cambridge from 1934 to 1953, then Knightbridge Professor of Moral Philosophy there from 1953 to 1967...

.

The paper also introduces the notion of definable number
Definable number
A real number a is first-order definable in the language of set theory, without parameters, if there is a formula φ in the language of set theory, with one free variable, such that a is the unique real number such that φ holds in the standard model of set theory .For the purposes of this article,...

s.

From September 1936 to July 1938 he spent most of his time at the Institute for Advanced Study
Institute for Advanced Study
The Institute for Advanced Study, located in Princeton, New Jersey, United States, is an independent postgraduate center for theoretical research and intellectual inquiry. It was founded in 1930 by Abraham Flexner...

, Princeton
Princeton, New Jersey
Princeton is a community located in Mercer County, New Jersey, United States. It is best known as the location of Princeton University, which has been sited in the community since 1756...

, New Jersey, studying under Alonzo Church
Alonzo Church
Alonzo Church was an American mathematician and logician who made major contributions to mathematical logic and the foundations of theoretical computer science. He is best known for the lambda calculus, Church–Turing thesis, Frege–Church ontology, and the Church–Rosser theorem.-Life:Alonzo Church...

. In addition to his purely mathematical work, he studied cryptology and also built three of four stages of an electro-mechanical binary multiplier. In June 1938 he obtained his PhD from Princeton; his dissertation (Systems of Logic Based on Ordinals
Systems of Logic Based on Ordinals
Systems of Logic Based on Ordinals was the PhD dissertation of the mathematician Alan Turing.The thesis was completed at Princeton under Alonzo Church and was a classic work in mathematics which introduced the concept of ordinal logic....

) introduced the concept of ordinal logic
Ordinal logic
In mathematics, ordinal logic is a logic associated with an ordinal number by recursively adding elements to a sequence of previous logics. The concept was introduced in 1938 by Alan Turing in his PhD dissertation at Princeton in view of Gödel's incompleteness theorems.While Gödel showed that every...

 and the notion of relative computing
Turing reduction
In computability theory, a Turing reduction from a problem A to a problem B, named after Alan Turing, is a reduction which solves A, assuming B is already known . It can be understood as an algorithm that could be used to solve A if it had available to it a subroutine for solving B...

, where Turing machines are augmented with so-called oracles
Oracle machine
In complexity theory and computability theory, an oracle machine is an abstract machine used to study decision problems. It can be visualized as a Turing machine with a black box, called an oracle, which is able to decide certain decision problems in a single operation. The problem can be of any...

, allowing a study of problems that cannot be solved by a Turing machine.

Back in Cambridge, he attended lectures by Ludwig Wittgenstein
Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He was professor in philosophy at the University of Cambridge from 1939 until 1947...

 about the foundations of mathematics
Foundations of mathematics
Foundations of mathematics is a term sometimes used for certain fields of mathematics, such as mathematical logic, axiomatic set theory, proof theory, model theory, type theory and recursion theory...

. The two argued and disagreed, with Turing defending formalism and Wittgenstein arguing that mathematics does not discover any absolute truths but rather invents them. He also started to work part-time with the Government Code and Cypher School (GCCS)
Government Communications Headquarters
The Government Communications Headquarters is a British intelligence agency responsible for providing signals intelligence and information assurance to the UK government and armed forces...

.

Cryptanalysis



During the Second World War, Turing was a leading participant in the efforts at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...

 to break German ciphers. Building on cryptanalysis work carried out in Poland by Marian Rejewski
Marian Rejewski
Marian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...

, Jerzy Różycki
Jerzy Rózycki
Jerzy Witold Różycki was a Polish mathematician and cryptologist who worked at breaking German Enigma-machine ciphers.-Life:Różycki was born in what is now Ukraine, the fourth and youngest child of Zygmunt Różycki, a pharmacist and graduate of Saint Petersburg University, and Wanda, née Benita. ...

 and Henryk Zygalski
Henryk Zygalski
Henryk Zygalski was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.-Life:...

 from Cipher Bureau before the war, he contributed several insights into breaking both the Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...

 and the Lorenz SZ 40/42 (a Teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...

 cipher attachment codenamed Tunny by the British), and was, for a time, head of Hut 8
Hut 8
Hut 8 was a section at Bletchley Park tasked with solving German naval Enigma messages. The section was led initially by Alan Turing...

, the section responsible for reading German naval signals.

From September 1938, Turing had been working part-time (notionally for the British Foreign Office
Foreign and Commonwealth Office
The Foreign and Commonwealth Office, commonly called the Foreign Office or the FCO is a British government department responsible for promoting the interests of the United Kingdom overseas, created in 1968 by merging the Foreign Office and the Commonwealth Office.The head of the FCO is the...

) with the Government Code and Cypher School (GCCS), the British code breaking organisation. He worked on the problem of the German Enigma machine, and collaborated with Dilly Knox
Dilly Knox
Alfred Dillwyn 'Dilly' Knox CMG was a classics scholar at King's College, Cambridge, and a British codebreaker...

, a senior GCCS
Government Communications Headquarters
The Government Communications Headquarters is a British intelligence agency responsible for providing signals intelligence and information assurance to the UK government and armed forces...

 codebreaker. On 4 September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GCCS.

In 1945, Turing was awarded the OBE
Order of the British Empire
The Most Excellent Order of the British Empire is an order of chivalry established on 4 June 1917 by George V of the United Kingdom. The Order comprises five classes in civil and military divisions...

 for his wartime services, but his work remained secret for many years.

Turing had something of a reputation for eccentricity at Bletchley Park. Jack Good, a cryptanalyst who worked with him, is quoted by Ronald Lewin as having said of Turing:
in the first week of June each year he would get a bad attack of hay fever, and he would cycle to the office wearing a service gas mask to keep the pollen off. His bicycle had a fault: the chain would come off at regular intervals. Instead of having it mended he would count the number of times the pedals went round and would get off the bicycle in time to adjust the chain by hand. Another of his eccentricities is that he chained his mug to the radiator pipes to prevent it being stolen.


While working at Bletchley, Turing, a talented long-distance runner, occasionally ran the 40 miles (64.4 km) to London when he was needed for high-level meetings, and he was capable of world-class marathon standards.

Turing–Welchman bombe


Within weeks of arriving at Bletchley Park, Turing had specified an electromechanical machine which could help break Enigma faster than bomba
Bomba (cryptography)
The bomba, or bomba kryptologiczna was a special-purpose machine designed about October 1938 by Polish Cipher Bureau cryptologist Marian Rejewski to break German Enigma-machine ciphers....

 from 1938, the bombe
Bombe
The bombe was an electromechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted signals during World War II...

, named after and building upon the original Polish-designed bomba. The bombe, with an enhancement suggested by mathematician Gordon Welchman
Gordon Welchman
Gordon Welchman was a British-American mathematician, university professor, World War II codebreaker at Bletchley Park, and author.-Education and early career:...

, became one of the primary tools, and the major automated one, used to attack Enigma-protected message traffic.
Jack Good opined:
Turing's most important contribution, I think, was of part of the design of the bombe, the cryptanalytic machine. He had the idea that you could use, in effect, a theorem in logic which sounds to the untrained ear rather absurd; namely that from a contradiction, you can deduce everything.


The bombe searched for possibly correct settings used for an Enigma message (i.e., rotor order, rotor settings, etc.), and used a suitable crib: a fragment of probable plaintext
Plaintext
In cryptography, plaintext is information a sender wishes to transmit to a receiver. Cleartext is often used as a synonym. Before the computer era, plaintext most commonly meant message text in the language of the communicating parties....

. For each possible setting of the rotors (which had of the order of 1019 states, or 1022 for the four-rotor U-boat variant), the bombe performed a chain of logical deductions based on the crib, implemented electrically. The bombe detected when a contradiction had occurred, and ruled out that setting, moving onto the next. Most of the possible settings would cause contradictions and be discarded, leaving only a few to be investigated in detail. Turing's bombe was first installed on 18 March 1940. More than two hundred bombes were in operation by the end of the war.

Hut 8 and Naval Enigma



Turing decided to tackle the particularly difficult problem of German naval Enigma "because no one else was doing anything about it and I could have it to myself". In December 1939, Turing solved the essential part of the naval indicator system, which was more complex than the indicator systems used by the other services. The same night that he solved the naval indicator system, he conceived the idea of Banburismus
Banburismus
Banburismus was a cryptanalytic process developed by Alan Turing at Bletchley Park in England during the Second World War. It was used by Bletchley Park's Hut 8 to help break German Kriegsmarine messages enciphered on Enigma machines. The process used sequential conditional probability to infer...

, a sequential statistical technique (what Abraham Wald
Abraham Wald
- See also :* Sequential probability ratio test * Wald distribution* Wald–Wolfowitz runs test...

 later called sequential analysis
Sequential analysis
In statistics, sequential analysis or sequential hypothesis testing is statistical analysis where the sample size is not fixed in advance. Instead data are evaluated as they are collected, and further sampling is stopped in accordance with a pre-defined stopping rule as soon as significant results...

) to assist in breaking naval Enigma, "though I was not sure that it would work in practice, and was not in fact sure until some days had actually broken". For this he invented a measure of weight of evidence that he called the Ban
Ban (information)
A ban, sometimes called a hartley or a dit , is a logarithmic unit which measures information or entropy, based on base 10 logarithms and powers of 10, rather than the powers of 2 and base 2 logarithms which define the bit. As a bit corresponds to a binary digit, so a ban is a decimal digit...

. Banburismus could rule out certain orders of the Enigma rotors, substantially reducing the time needed to test settings on the bombes.

In 1941, Turing proposed marriage to Hut 8 co-worker Joan Clarke, a fellow mathematician, but their engagement was short-lived. After admitting his homosexuality to his fiancée, who was reportedly "unfazed" by the revelation, Turing decided that he could not go through with the marriage.

In July 1942, Turing devised a technique termed Turingery
Turingery
Turingery or Turing's Method was a hand codebreaking method devised by the mathematician and cryptanalyst Alan Turing at the British Government Code and Cypher School at Bletchley Park during World War II...

(or jokingly Turingismus) for use against the Lorenz cipher
Lorenz cipher
The Lorenz SZ40, SZ42A and SZ42B were German rotor cipher machines used by the German Army during World War II. They were developed by C. Lorenz AG in Berlin. They implemented a Vernam stream cipher...

 messages produced by the Germans' new Geheimschreiber machine (secret writer). This was codenamed Tunny at Bletchley Park. He also introduced the Tunny team to Tommy Flowers
Tommy Flowers
Thomas "Tommy" Harold Flowers, MBE was an English engineer. During World War II, Flowers designed Colossus, the world's first programmable electronic computer, to help solve encrypted German messages.-Early life:...

 who, under the guidance of Max Newman
Max Newman
Maxwell Herman Alexander "Max" Newman, FRS was a British mathematician and codebreaker.-Pre–World War II:Max Newman was born Maxwell Neumann in Chelsea, London, England, on 7 February 1897...

, went on to build the Colossus computer
Colossus computer
Not to be confused with the fictional computer of the same name in the movie Colossus: The Forbin Project.Colossus was the world's first electronic, digital, programmable computer. Colossus and its successors were used by British codebreakers to help read encrypted German messages during World War II...

, the world's first programmable digital electronic computer, which replaced a simpler prior machine (the Heath Robinson
Heath Robinson (codebreaking machine)
Heath Robinson was a machine used by British codebreakers at Bletchley Park during World War II to solve messages in the German teleprinter cipher used by the Lorenz SZ40/42 cipher machine; the cipher and machine were called "Tunny" by the codebreakers, who named different German teleprinter...

) and whose superior speed allowed the brute-force decryption techniques to be applied usefully to the daily changing cyphers. A frequent misconception is that Turing was a key figure in the design of Colossus; this was not the case.

Turing travelled to the United States in November 1942 and worked with U.S. Navy cryptanalysts on Naval Enigma and bombe construction in Washington, and assisted at Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...

 with the development of secure speech devices. He returned to Bletchley Park in March 1943. During his absence, Hugh Alexander
Conel Hugh O'Donel Alexander
Conel Hugh O'Donel Alexander, CMG, CBE was an Irish-born British cryptanalyst, chess player, and chess writer. He worked on the German Enigma machine at Bletchley Park during World War II, and was later the head of the cryptanalysis division at GCHQ for over 20 years...

 had officially assumed the position of head of Hut 8, although Alexander had been de facto head for some time—Turing having little interest in the day-to-day running of the section. Turing became a general consultant for cryptanalysis at Bletchley Park.

Alexander wrote as follows about his contribution:
There should be no question in anyone's mind that Turing's work was the biggest factor in Hut 8's success. In the early days he was the only cryptographer who thought the problem worth tackling and not only was he primarily responsible for the main theoretical work within the Hut but he also shared with Welchman and Keen the chief credit for the invention of the Bombe. It is always difficult to say that anyone is absolutely indispensable but if anyone was indispensable to Hut 8 it was Turing. The pioneer's work always tends to be forgotten when experience and routine later make everything seem easy and many of us in Hut 8 felt that the magnitude of Turing's contribution was never fully realised by the outside world.


In the latter part of the war he moved to work at Hanslope Park, where he further developed his knowledge of electronics with the assistance of engineer Donald Bayley. Together they undertook the design and construction of a portable secure voice
Secure voice
Secure voice is a term in cryptography for the encryption of voice communication over a range of communication types such as radio, telephone or IP.-History:...

 communications machine codenamed Delilah. It was intended for different applications, lacking capability for use with long-distance radio transmissions, and in any case, Delilah was completed too late to be used during the war. Though Turing demonstrated it to officials by encrypting/decrypting a recording of a Winston Churchill
Winston Churchill
Sir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...

 speech, Delilah was not adopted for use. Turing also consulted with Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...

 on the development of SIGSALY
SIGSALY
In cryptography, SIGSALY was a secure speech system used in World War II for the highest-level Allied communications....

, a secure voice system that was used in the later years of the war.

Early computers and the Turing test


From 1945 to 1947 Turing lived in Church Street, Hampton while he worked on the design of the ACE
ACE (computer)
The Automatic Computing Engine was an early electronic stored-program computer design produced by Alan Turing at the invitation of John R. Womersley, superintendent of the Mathematics Division of the National Physical Laboratory . The use of the word Engine was in homage to Charles Babbage and his...

 (Automatic Computing Engine) at the National Physical Laboratory
National Physical Laboratory, UK
The National Physical Laboratory is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, London, England. It is the largest applied physics organisation in the UK.-Description:...

. He presented a paper on 19 February 1946, which was the first detailed design of a stored-program computer
Stored-program computer
A stored-program computer is one which stores program instructions in electronic memory. Often the definition is extended with the requirement that the treatment of programs and data in memory be interchangeable or uniform....

. Although ACE was a feasible design, the secrecy surrounding the wartime work at Bletchley Park led to delays in starting the project and he became disillusioned. In late 1947 he returned to Cambridge for a sabbatical year. While he was at Cambridge, the Pilot ACE
Pilot ACE
The Pilot ACE was one of the first computers built in the United Kingdom, at the National Physical Laboratory in the early 1950s.It was a preliminary version of the full ACE, which had been designed by Alan Turing. After Turing left NPL , James H...

 was built in his absence. It executed its first program on 10 May 1950.

In 1948, he was appointed Reader
Reader (academic rank)
The title of Reader in the United Kingdom and some universities in the Commonwealth nations like Australia and New Zealand denotes an appointment for a senior academic with a distinguished international reputation in research or scholarship...

 in the Mathematics Department
School of Mathematics, University of Manchester
The School of Mathematics at the University of Manchester is one of the largest mathematics departments in the United Kingdom, with around 80 academic staff and an undergraduate intake of roughly 400 a year and another 200 postgraduate students...

 at Manchester
Victoria University of Manchester
The Victoria University of Manchester was a university in Manchester, England. On 1 October 2004 it merged with the University of Manchester Institute of Science and Technology to form a new entity, "The University of Manchester".-1851 - 1951:The University was founded in 1851 as Owens College,...

 (now part of The University of Manchester). In 1949, he became Deputy Director of the computing laboratory at the University of Manchester
Victoria University of Manchester
The Victoria University of Manchester was a university in Manchester, England. On 1 October 2004 it merged with the University of Manchester Institute of Science and Technology to form a new entity, "The University of Manchester".-1851 - 1951:The University was founded in 1851 as Owens College,...

, and worked on software for one of the earliest stored-program
Von Neumann architecture
The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...

 computers—the Manchester Mark 1
Manchester Mark 1
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Small-Scale Experimental Machine or "Baby" . It was also called the Manchester Automatic Digital Machine, or MADM...

. During this time he continued to do more abstract work, and in "Computing machinery and intelligence
Computing machinery and intelligence
Computing Machinery and Intelligence, written by Alan Turing and published in 1950 in Mind, is a seminal paper on the topic of artificial intelligence in which the concept of what is now known as the Turing test was introduced to a wide audience....

" (Mind, October 1950), Turing addressed the problem of artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

, and proposed an experiment which became known as the Turing test
Turing test
The Turing test is a test of a machine's ability to exhibit intelligent behaviour. In Turing's original illustrative example, a human judge engages in a natural language conversation with a human and a machine designed to generate performance indistinguishable from that of a human being. All...

, 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. In the paper, Turing suggested that rather than building a program to simulate the adult mind, it would be better rather to produce a simpler one to simulate a child's mind and then to subject it to a course of education. A reversed form of the Turing test is widely used on the Internet; the CAPTCHA
CAPTCHA
A CAPTCHA is a type of challenge-response test used in computing as an attempt to ensure that the response is generated by a person. The process usually involves one computer asking a user to complete a simple test which the computer is able to generate and grade...

 test is intended to determine whether the user is a human or a computer.

In 1948, Turing, working with his former undergraduate colleague, D. G. Champernowne
D. G. Champernowne
David Gawen Champernowne was an English economist and mathematician.After academic work at Cambridge and the London School of Economics, he worked at the London School of Economics and Cambridge University...

, began writing a chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...

 program for a computer that did not yet exist. In 1952, lacking a computer powerful enough to execute the program, Turing played a game in which he simulated the computer, taking about half an hour per move. The game was recorded. The program lost to Turing's colleague Alick Glennie
Alick Glennie
Alick Edwards Glennie was a British computer scientist, most famous for having developed Autocode, which many people regard as the first ever computer compiler. Glennie worked with Alan Turing on several projects, including the Manchester Mark 1...

, although it is said that it won a game against Champernowne's wife.

His Turing test
Turing test
The Turing test is a test of a machine's ability to exhibit intelligent behaviour. In Turing's original illustrative example, a human judge engages in a natural language conversation with a human and a machine designed to generate performance indistinguishable from that of a human being. All...

 was a significant and characteristically provocative and lasting contribution to the debate regarding artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

, which continues after more than half a century.

He also invented the LU decomposition
LU decomposition
In linear algebra, LU decomposition is a matrix decomposition which writes a matrix as the product of a lower triangular matrix and an upper triangular matrix. The product sometimes includes a permutation matrix as well. This decomposition is used in numerical analysis to solve systems of linear...

 method in 1948, used today for solving an equations matrix.

Pattern formation and mathematical biology


Turing worked from 1952 until his death in 1954 on mathematical biology
Mathematical biology
Mathematical and theoretical biology is an interdisciplinary scientific research field with a range of applications in biology, medicine and biotechnology...

, specifically morphogenesis
Morphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...

. He published one paper on the subject called The Chemical Basis of Morphogenesis
The chemical basis of morphogenesis
The Chemical Basis of Morphogenesis is an article written by Alan Turing in 1951 describing the way in which non-uniformity may arise naturally out of a homogeneous, uniform state....

in 1952, putting forth the Turing hypothesis of pattern formation. His central interest in the field was understanding Fibonacci phyllotaxis
Phyllotaxis
In botany, phyllotaxis or phyllotaxy is the arrangement of leaves on a plant stem .- Pattern structure :...

, the existence of Fibonacci number
Fibonacci number
In mathematics, the Fibonacci numbers are the numbers in the following integer sequence:0,\;1,\;1,\;2,\;3,\;5,\;8,\;13,\;21,\;34,\;55,\;89,\;144,\; \ldots\; ....

s in plant structures. He used reaction–diffusion equations which are central to the field of pattern formation
Pattern formation
The science of pattern formation deals with the visible, orderly outcomes of self-organisation and the common principles behind similar patterns....

. Later papers went unpublished until 1992 when Collected Works of A.M. Turing was published. His contribution is considered a seminal piece of work in this field.

Conviction for indecency


In January 1952, Turing met Arnold Murray outside a cinema in Manchester. After a lunch date, Turing invited Murray to spend the weekend with him at his house, an invitation which Murray accepted although he did not show up. The pair met again in Manchester the following Monday, when Murray agreed to accompany Turing to the latter's house. A few weeks later Murray visited Turing's house again, and apparently spent the night there.

After Murray helped an accomplice to break into his house, Turing reported the crime to the police. During the investigation, Turing acknowledged a sexual relationship with Murray. Homosexual acts were illegal in the United Kingdom at that time, and so both were charged with gross indecency under Section 11 of the Criminal Law Amendment Act 1885
Criminal Law Amendment Act 1885
The Criminal Law Amendment Act 1885 , or "An Act to make further provision for the Protection of Women and Girls, the suppression of brothels, and other purposes", was the latest in a 25-year series of legislation in the United Kingdom beginning with the Offences against the Person Act 1861 that...

.

Turing was given a choice between imprisonment or probation conditional on his agreement to undergo hormonal
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...

 treatment
Chemical castration
Chemical castration is the administration of medication designed to reduce libido and sexual activity, usually in the hope of preventing rapists, child molesters and other sex offenders from repeating their crimes...

 designed to reduce libido
Libido
Libido refers to a person's sex drive or desire for sexual activity. The desire for sex is an aspect of a person's sexuality, but varies enormously from one person to another, and it also varies depending on circumstances at a particular time. A person who has extremely frequent or a suddenly...

. He accepted chemical castration
Chemical castration
Chemical castration is the administration of medication designed to reduce libido and sexual activity, usually in the hope of preventing rapists, child molesters and other sex offenders from repeating their crimes...

 via oestrogen hormone injections.

Turing's conviction led to the removal of his security clearance, and barred him from continuing with his cryptographic consultancy for GCHQ. At the time, there was acute public anxiety about spies and homosexual entrapment by Soviet agents, because of the recent exposure of the first two members of the Cambridge Five
Cambridge Five
The Cambridge Five was a ring of spies, recruited in part by Russian talent spotter Arnold Deutsch in the United Kingdom, who passed information to the Soviet Union during World War II and at least into the early 1950s...

, Guy Burgess
Guy Burgess
Guy Francis De Moncy Burgess was a British-born intelligence officer and double agent, who worked for the Soviet Union. He was part of the Cambridge Five spy ring that betrayed Western secrets to the Soviets before and during the Cold War...

 and Donald Maclean
Donald Duart Maclean
Donald Duart Maclean was a British diplomat and member of the Cambridge Five who were members of MI5, MI6 or the diplomatic service who acted as spies for the Soviet Union in the Second World War and beyond. He was recruited as a "straight penetration agent" while an undergraduate at Cambridge by...

, as KGB
KGB
The KGB was the commonly used acronym for the . It was the national security agency of the Soviet Union from 1954 until 1991, and was the premier internal security, intelligence, and secret police organization during that time.The State Security Agency of the Republic of Belarus currently uses the...

 double agent
Double agent
A double agent, commonly abbreviated referral of double secret agent, is a counterintelligence term used to designate an employee of a secret service or organization, whose primary aim is to spy on the target organization, but who in fact is a member of that same target organization oneself. They...

s. Turing was never accused of espionage but, as with all who had worked at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...

, was prevented from discussing his war work.

Death


On 8 June 1954, Turing's cleaner found him dead; he had died the previous day. A post-mortem examination established that the cause of death was cyanide poisoning. When his body was discovered an apple lay half-eaten beside his bed, and although the apple was not tested for cyanide, it is speculated that this was the means by which a fatal dose was delivered. An inquest
Inquest
Inquests in England and Wales are held into sudden and unexplained deaths and also into the circumstances of discovery of a certain class of valuable artefacts known as "treasure trove"...

 determined that he had committed suicide, and he was cremated at Woking Crematorium
Woking Crematorium
Woking Crematorium is a crematorium in Woking, a large town in the west of Surrey, England. Established in 1878, it was the first custom-built crematorium in the United Kingdom and is closely linked to the history of cremation in this country.-Location:...

 on 12 June 1954. Turing's mother argued strenuously that the ingestion was accidental, caused by her son's careless storage of laboratory chemicals. Biographer Andrew Hodges
Andrew Hodges
Andrew Hodges is a mathematician, an author and a pioneer of the gay liberation movement of the 1970s.For the past decades , Hodges has focused his research activities on the twistor theory — the new approach to the problems of fundamental physics pioneered by the mathematician Roger...

 suggests that Turing may have killed himself in an ambiguous way quite deliberately, to give his mother some plausible deniability
Plausible deniability
Plausible deniability is, at root, credible ability to deny a fact or allegation, or to deny previous knowledge of a fact. The term most often refers to the denial of blame in chains of command, where upper rungs quarantine the blame to the lower rungs, and the lower rungs are often inaccessible,...

. David Leavitt has suggested that Turing was re-enacting a scene from the 1937 film Snow White
Snow White and the Seven Dwarfs (1937 film)
Snow White and the Seven Dwarfs is a 1937 American animated film based on Snow White, a German fairy tale by the Brothers Grimm. It was the first full-length cel-animated feature in motion picture history, as well as the first animated feature film produced in America, the first produced in full...

, his favourite fairy tale
Fairy tale
A fairy tale is a type of short story that typically features such folkloric characters, such as fairies, goblins, elves, trolls, dwarves, giants or gnomes, and usually magic or enchantments. However, only a small number of the stories refer to fairies...

, pointing out that he took "an especially keen pleasure in the scene where the Wicked Witch immerses her apple in the poisonous brew."

Epitaph



Recognition and tributes


A biography published by the Royal Society shortly after Turing's death (and while his wartime work was still subject to the Official Secrets Act) recorded:

Three remarkable papers written just before the war, on three diverse mathematical subjects, show the quality of the work that might have been produced if he had settled down to work on some big problem at that critical time. For his work at the Foreign Office he was awarded the OBE.


Since 1966, the Turing Award
Turing Award
The Turing Award, in full The ACM A.M. Turing Award, is an annual award given by the Association for Computing Machinery to "an individual selected for contributions of a technical nature made to the computing community. The contributions should be of lasting and major technical importance to the...

 has been given annually by the Association for Computing Machinery
Association for Computing Machinery
The Association for Computing Machinery is a learned society for computing. It was founded in 1947 as the world's first scientific and educational computing society. Its membership is more than 92,000 as of 2009...

 to a person for technical contributions to the computing community. It is widely considered to be the computing world's highest honour, equivalent to the Nobel Prize.

Breaking the Code
Breaking the Code
Breaking the Code is a 1986 play by Hugh Whitemore about British mathematician Alan Turing, who was a key player in the breaking of the German Enigma code at Bletchley Park during World War II...

is a 1986 play by Hugh Whitemore
Hugh Whitemore
Hugh Whitemore is an English playwright and screenwriter.Whitemore studied for the stage at London's Royal Academy of Dramatic Art, where he is now a Member of the Council. He began his writing career in British television with both original teleplays and adaptations of classic works by Charles...

 about Alan Turing. The play ran in London's West End
West End theatre
West End theatre is a popular term for mainstream professional theatre staged in the large theatres of London's 'Theatreland', the West End. Along with New York's Broadway theatre, West End theatre is usually considered to represent the highest level of commercial theatre in the English speaking...

 beginning in November 1986 and on Broadway from 15 November 1987 to 10 April 1988. There was also a 1996 BBC television production. In all cases, Derek Jacobi
Derek Jacobi
Sir Derek George Jacobi, CBE is an English actor and film director.A "forceful, commanding stage presence", Jacobi has enjoyed a highly successful stage career, appearing in such stage productions as Hamlet, Uncle Vanya, and Oedipus the King. He received a Tony Award for his performance in...

 played Turing. The Broadway production was nominated for three Tony Award
Tony Award
The Antoinette Perry Award for Excellence in Theatre, more commonly known as a Tony Award, recognizes achievement in live Broadway theatre. The awards are presented by the American Theatre Wing and The Broadway League at an annual ceremony in New York City. The awards are given for Broadway...

s including Best Actor in a Play, Best Featured Actor in a Play, and Best Direction of a Play, and for two Drama Desk Award
Drama Desk Award
The Drama Desk Awards, which are given annually in a number of categories, are the only major New York theater honors for which productions on Broadway, Off-Broadway, Off-Off-Broadway compete against each other in the same category...

s, for Best Actor and Best Featured Actor.

On 23 June 1998, on what would have been Turing's 86th birthday, Andrew Hodges
Andrew Hodges
Andrew Hodges is a mathematician, an author and a pioneer of the gay liberation movement of the 1970s.For the past decades , Hodges has focused his research activities on the twistor theory — the new approach to the problems of fundamental physics pioneered by the mathematician Roger...

, his biographer, unveiled an official English Heritage
English Heritage
English Heritage . is an executive non-departmental public body of the British Government sponsored by the Department for Culture, Media and Sport...

 Blue Plaque
Blue plaque
A blue plaque is a permanent sign installed in a public place to commemorate a link between that location and a famous person or event, serving as a historical marker....

 at his birthplace and childhood home in Warrington Crescent, London, later the Colonnade Hotel.
To mark the 50th anniversary of his death, a memorial plaque was unveiled on 7 June 2004 at his former residence, Hollymeade, in Wilmslow
Wilmslow
-Economy:Wilmslow is well known, like Alderley Edge, for having many famous residents, notably footballers, stars of Coronation Street and rich North West businessmen. The town is part of the so-called Golden Triangle in the north west together with Alderley Edge and Prestbury...

, Cheshire
Cheshire
Cheshire is a ceremonial county in North West England. Cheshire's county town is the city of Chester, although its largest town is Warrington. Other major towns include Widnes, Congleton, Crewe, Ellesmere Port, Runcorn, Macclesfield, Winsford, Northwich, and Wilmslow...

.

On 13 March 2000, Saint Vincent and the Grenadines
Saint Vincent and the Grenadines
Saint Vincent and the Grenadines is an island country in the Lesser Antilles chain, namely in the southern portion of the Windward Islands, which lie at the southern end of the eastern border of the Caribbean Sea where the latter meets the Atlantic Ocean....

 issued a set of stamps
Postage stamp
A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...

 to celebrate the greatest achievements of the 20th century, one of which carries a recognisable portrait of Turing against a background of repeated 0s and 1s, and is captioned: "1937: Alan Turing's theory of digital computing".

On 28 October 2004, a bronze statue of Alan Turing sculpted by John W. Mills
John W. Mills
John William Mills is an English sculptor.He was born in London on March 4, 1933.He studied at Hammersmith School of Art 1947-1954, and at the Royal College of Art 1956-1960.He was a resident at Digswell House 1962-1966....

 was unveiled at the University of Surrey
University of Surrey
The University of Surrey is a university located within the county town of Guildford, Surrey in the South East of England. It received its charter on 9 September 1966, and was previously situated near Battersea Park in south-west London. The institution was known as Battersea College of Technology...

 in Guildford
Guildford
Guildford is the county town of Surrey. England, as well as the seat for the borough of Guildford and the administrative headquarters of the South East England region...

, marking the 50th anniversary of Turing's death; it portrays him carrying his books across the campus.

In 2006, Boston Pride named Turing their Honorary Grand Marshal.

Turing was one of four mathematicians examined in the 2008 BBC documentary entitled "Dangerous Knowledge".

The Princeton Alumni Weekly named Turing the second most significant alumnus in the history of Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....

, second only to President James Madison
James Madison
James Madison, Jr. was an American statesman and political theorist. He was the fourth President of the United States and is hailed as the “Father of the Constitution” for being the primary author of the United States Constitution and at first an opponent of, and then a key author of the United...

.

A 1.5-ton, life-size statue of Turing was unveiled on 19 June 2007 at Bletchley Park. Built from approximately half a million pieces of Welsh
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

 slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...

, it was sculpted by Stephen Kettle
Stephen Kettle
Stephen Kettle is a British sculptor who works exclusively with slate.His best known works include Supermarine Spitfire designer R. J...

, having been commissioned by the late American billionaire Sidney Frank
Sidney Frank
Sidney E. Frank was an American businessman who became a billionaire through his promotion of Grey Goose vodka and Jägermeister.-Early life, family, education:...

.

Turing has been honoured in various ways in Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...

, the city where he worked towards the end of his life. In 1994, a stretch of the A6010 road (the Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...

 city intermediate ring road) was named "Alan Turing Way". Part of this road runs alongside the City of Manchester Stadium
City of Manchester Stadium
The City of Manchester Stadium in Manchester, England – also known as the Etihad Stadium for sponsorship purposes– is the home ground of...

, where Manchester City play their games. A bridge carrying this road was widened, and carries the name Alan Turing Bridge. A statue of Turing
Alan Turing Memorial
The Alan Turing Memorial, situated in the Sackville Park in Manchester, England, is in memory of Alan Turing, a father of modern computing. Turing committed suicide in 1954 after being prosecuted by the police because of his homosexuality...

 was unveiled in Manchester on 23 June 2001. It is in Sackville Park, between the University of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...

 building on Whitworth Street and the Canal Street gay village
Gay village
A gay village is an urban geographic location with generally recognized boundaries where a large number of lesbian, gay, bisexual, and transgender people live or frequent...

. The memorial statue, depicts the "father of Computer Science" sitting on a bench at a central position in the park. The statue was unveiled on Turing's birthday.


Turing is shown holding an apple—a symbol classically used to represent forbidden love, the object that inspired Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

's theory of gravitation, and the means of Turing's own death. The cast bronze bench carries in relief the text 'Alan Mathison Turing 1912–1954', and the motto 'Founder of Computer Science' as it would appear if encoded by an Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...

: 'IEKYF ROMSI ADXUO KVKZC GUBJ'.

A plinth at the statue's feet says 'Father of computer science, mathematician, logician, wartime codebreaker, victim of prejudice'. There is also a Bertrand Russell
Bertrand Russell
Bertrand Arthur William Russell, 3rd Earl Russell, OM, FRS was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he considered himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these things...

 quotation saying 'Mathematics, rightly viewed, possesses not only truth, but supreme beauty—a beauty cold and austere, like that of sculpture.' The sculptor buried his old Amstrad
Amstrad
Amstrad is a British electronics company, now wholly owned by BSkyB. As of 2006, Amstrad's main business is manufacturing Sky Digital interactive boxes....

 computer, which was an early popular home computer, under the plinth, as a tribute to "the godfather of all modern computers".

In 1999, Time Magazine named Turing as one of the 100 Most Important People of the 20th century
Time 100: The Most Important People of the Century
Time 100: The Most Important People of the Century is a compilation of the 20th century's 100 most influential people, published in Time magazine in 1999....

 for his role in the creation of the modern computer, and stated: "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." Turing is featured in the 1999 Neal Stephenson
Neal Stephenson
Neal Town Stephenson is an American writer known for his works of speculative fiction.Difficult to categorize, his novels have been variously referred to as science fiction, historical fiction, cyberpunk, and postcyberpunk...

 novel "Cryptonomicon
Cryptonomicon
Cryptonomicon is a 1999 novel by American author Neal Stephenson. The novel follows the exploits of two groups of people in two different time periods, presented in alternating chapters...

."

In 2002, Turing was ranked twenty-first on the BBC nationwide poll of the 100 Greatest Britons
100 Greatest Britons
100 Greatest Britons was broadcast in 2002 by the BBC. The programme was the result of a vote conducted to determine whom the United Kingdom public considers the greatest British people in history. The series, Great Britons, included individual programmes on the top ten, with viewers having further...

.

The logo of Apple computer is often erroneously referred to as a tribute to Alan Turing, with the bite mark a reference to his method of suicide. Both the designer of the logo and the company deny that there is any homage to Turing in the design of the logo.

In 2010, actor/playwright Jade Esteban Estrada portrayed Turing in the solo musical, "ICONS: The Lesbian and Gay History of the World, Vol. 4."

Turing is mentioned several times in the DLC for the 2K Games "Bioshock 2" He is mentioned several times by the voice actor who portrays C. M. Porter. There is also a telegram in Porter's office requesting he come to London and work with Turing. He is also mentioned in Assassin's Creed: Brotherhood
Assassin's Creed: Brotherhood
Assassin's Creed: Brotherhood is a historical third person, stealth action-adventure video game developed by Ubisoft for PlayStation 3, Xbox 360, Microsoft Windows and Mac OS X. It was released for PlayStation 3 and Xbox 360 in November 2010, Microsoft Windows in March 2011 and Mac OS X in May 2011...

, when an employee of Abstergo Industries orders him to be killed and commands the would-be executioner to "make it look biblical".

In February 2011, Turing's papers from the Second World War were bought for the nation with an 11th-hour bid by the National Heritage Memorial Fund
National Heritage Memorial Fund
The National Heritage Memorial Fund is a non-departmental public body set up under the National Heritage Act 1980 in memory of people who gave their lives for the United Kingdom....

, allowing them to stay at Bletchley Park.

Government apology


In August 2009, John Graham-Cumming
John Graham-Cumming
John Graham-Cumming is a British programmer best known for having originated a successful petition to the British Government asking for an apology for its persecution of Alan Turing for his homosexuality....

 started a petition urging the British Government to posthumously apologise to Alan Turing for prosecuting him as a homosexual. The petition received thousands of signatures. Prime Minister Gordon Brown
Gordon Brown
James Gordon Brown is a British Labour Party politician who was the Prime Minister of the United Kingdom and Leader of the Labour Party from 2007 until 2010. He previously served as Chancellor of the Exchequer in the Labour Government from 1997 to 2007...

 acknowledged the petition, releasing a statement on 10 September 2009 apologising and describing Turing's treatment as "appalling":

Thousands of people have come together to demand justice for Alan Turing and recognition of the appalling way he was treated. While Turing was dealt with under the law of the time and we can't put the clock back, his treatment was of course utterly unfair and I am pleased to have the chance to say how deeply sorry I and we all are for what happened to him ... So on behalf of the British government, and all those who live freely thanks to Alan's work I am very proud to say: we're sorry, you deserved so much better.

Tributes by universities



A celebration of Turing's life and achievements arranged by the British Logic Colloquium and the British Society for the History of Mathematics
British Society for the History of Mathematics
The British Society for the History of Mathematics was founded in 1971 to promote research into the history of mathematics at all levels and to further the use of the history of mathematics in education....

 was held on 5 June 2004.
  • The 'Turing Room' at the University of Edinburgh's School of Informatics
    University of Edinburgh School of Informatics
    The School of Informatics is an academic unit of the University of Edinburgh, in Scotland, responsible for research, teaching, outreach and commercialisation in Informatics....

     houses a bust of Turing by Eduardo Paolozzi
    Eduardo Paolozzi
    Sir Eduardo Luigi Paolozzi, KBE, RA , was a Scottish sculptor and artist. He was a major figure in the international art sphere, while, working on his own interpretation and vision of the world. Paolozzi investigated how we can fit into the modern world to resemble our fragmented civilization...

    , and a set (#42/50) of his Turing prints (2000).
  • The University of Surrey
    University of Surrey
    The University of Surrey is a university located within the county town of Guildford, Surrey in the South East of England. It received its charter on 9 September 1966, and was previously situated near Battersea Park in south-west London. The institution was known as Battersea College of Technology...

     has a statue of Turing on their main piazza.
  • Istanbul Bilgi University
    Istanbul Bilgi University
    Istanbul Bilgi University is a private, non-profit university in Istanbul, Turkey. It was actually established in 1994 under the name ISIS , but its name was changed to Istanbul Bilgi University with the foundation of the school on June 7, 1996...

     organises an annual conference on the theory of computation called "Turing Days".
  • The University of Texas at Austin
    University of Texas at Austin
    The University of Texas at Austin is a state research university located in Austin, Texas, USA, and is the flagship institution of the The University of Texas System. Founded in 1883, its campus is located approximately from the Texas State Capitol in Austin...

     has an honours computer science programme named the Turing Scholars.
  • In the early 1960s Stanford University
    Stanford University
    The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

     named the sole lecture room of the Polya Hall Mathematics building "Alan Turing Auditorium".
  • One of the amphitheatres of the Computer Science department (LIFL
    Laboratoire d'Informatique Fondamentale de Lille
    The Laboratoire d'Informatique Fondamentale de Lille , is a computer science research laboratory of Lille University of Science and Technology , in Lille, France...

    ) at the University of Lille
    University of Lille
    The original university in the Lille region of France was the University of Douai established in 1559 in Douai and that was moved to Lille in 1887.University campuses in the Academy of Lille are members of the Université Lille Nord de France and European Doctoral College Lille Nord-Pas de...

     in Northern France is named in honour of Alan M. Turing (the other amphitheatre is named after Kurt Gödel
    Kurt Gödel
    Kurt Friedrich Gödel was an Austrian logician, mathematician and philosopher. Later in his life he emigrated to the United States to escape the effects of World War II. One of the most significant logicians of all time, Gödel made an immense impact upon scientific and philosophical thinking in the...

    ).
  • The Department of Computer Science at Pontifical Catholic University of Chile
    Pontifical Catholic University of Chile
    The Pontifical Catholic University of Chile is one of the six Catholic Universities existing in the Chilean university system and one of the two Pontifical Universities in the country, along with the Pontifical Catholic University of Valparaíso. It is also one of Chile's oldest universities and...

    , the Polytechnic University of Puerto Rico
    Polytechnic University of Puerto Rico
    The Polytechnic University of Puerto Rico —commonly referred as Poly or La Poly in Spanish— is a private non-profit university located in San Juan, Puerto Rico...

    , Los Andes University
    University of the Andes, Colombia
    The University of the Andes , is a coeducational, nonsectarian private university located in city centre Bogotá, Colombia. Founded in 1948, the University has 9 faculties: Administration, Architecture and Design, Arts and Humanities, Sciences, Social Sciences, Law, Economics, Engineering and...

     in Bogotá
    Bogotá
    Bogotá, Distrito Capital , from 1991 to 2000 called Santa Fé de Bogotá, is the capital, and largest city, of Colombia. It is also designated by the national constitution as the capital of the department of Cundinamarca, even though the city of Bogotá now comprises an independent Capital district...

    , Colombia
    Colombia
    Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

    , King's College, Cambridge
    King's College, Cambridge
    King's College is a constituent college of the University of Cambridge, England. The college's full name is "The King's College of our Lady and Saint Nicholas in Cambridge", but it is usually referred to simply as "King's" within the University....

    , Bangor University
    Bangor University
    Bangor University is a university based in the city of Bangor in the county of Gwynedd in North Wales-United Kingdom.It was officially known for most of its history as the University College of North Wales...

     in Wales
    Wales
    Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

     and University of Mons
    University of Mons
    The University of Mons is a new Belgian university located in the city of Mons, created by merging the Engineering Faculty of Mons and the University of Mons-Hainaut...

     in Belgium
    Belgium
    Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

     have computer laboratories named after Turing.
  • The University of Manchester
    University of Manchester
    The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...

    , the Open University
    Open University
    The Open University is a distance learning and research university founded by Royal Charter in the United Kingdom...

    , Oxford Brookes University
    Oxford Brookes University
    Oxford Brookes University is a new university in Oxford, England. It was named to honour the school's founding principal, John Brookes. It has been ranked as the best new university by the Sunday Times University Guide 10 years in a row...

     and Aarhus University (in Århus, Denmark
    Denmark
    Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

    ) all have buildings named after Turing.
  • Alan Turing Road in the Surrey Research Park
    Surrey Research Park
    The Surrey Research Park is located in Guildford, Surrey, UK close to the A3 road and the Royal Surrey County Hospital. The park is owned and run by the University of Surrey....

     is named for Alan Turing.
  • Carnegie Mellon University
    Carnegie Mellon University
    Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....

     has a granite bench, situated in the Hornbostel Mall, with the name "A. M. Turing" carved across the top, "Read" down the left leg, and "Write" down the other.
  • The École Internationale des Sciences du Traitement de l'Information has named its recently acquired third building "Turing".
  • The University of Ghent has one of its main computer rooms (in a building used mostly by mathematicians and computing scientists) named after Alan Turing.
  • The University of Oregon
    University of Oregon
    -Colleges and schools:The University of Oregon is organized into eight schools and colleges—six professional schools and colleges, an Arts and Sciences College and an Honors College.- School of Architecture and Allied Arts :...

     has a bust of Turing on the side of the Deschutes Hall, the computer science building.

Centenary commemoration


To mark the 100th anniversary of Turing's birth, the Turing Centenary Advisory Committee (TCAC) is coordinating the Alan Turing Year
Alan Turing Year
The Alan Turing Year 2012 will be a celebration of the life and scientific influence of Alan Turing on the occasion of the centenary of his birth on 23 June 1912...

, a year-long programme of events around the world honouring Turing's life and achievements. The TCAC working with the University of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...

 faculty members and a broad spectrum of people from Cambridge University and Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...

, is chaired by S. Barry Cooper
S. Barry Cooper
S. Barry Cooper is a British mathematician and computability theorist. He is currently Professor of Mathematical Logic at the University of Leeds. His book Computability Theory has made this basic but technical research area accessible to a new generation of students...

, with Alan Turing's nephew Sir John Dermot Turing acting as TCAC Honorary President.

Events are scheduled in many countries around the world including the USA, Brazil, China, Czech Republic, the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

, New Zealand, Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

, Spain, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, Italy, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 and Germany. The keystone events will be a three-day conference in Manchester, UK in June examining Turing's mathematical and code-breaking achievements, and a Turing Centenary Conference in Cambridge organised by King's College, Cambridge
King's College, Cambridge
King's College is a constituent college of the University of Cambridge, England. The college's full name is "The King's College of our Lady and Saint Nicholas in Cambridge", but it is usually referred to simply as "King's" within the University....

 and the association Computability in Europe
Computability in Europe
Computability in Europe is an international organization of mathematicians, logicians, computer scientists, philosophers, theoretical physicists and others interested in new developments in computability and in their underlying significance for the real world...

.

See also


  • Good–Turing frequency estimation
  • Turing degree
    Turing degree
    In computer science and mathematical logic the Turing degree or degree of unsolvability of a set of natural numbers measures the level of algorithmic unsolvability of the set...

  • Turing machine examples
    Turing machine examples
    -Turing's very first example:The following table is Turing's very first example :With regard to what actions the machine actually does, Turing states the following:...

  • Turing switch
    Turing switch
    The Turing switch is a logical construction similar to the Turing machine. The Turing switch models the operation of a basic network switch in a network of switches, much the same as a Turing machine models the operation of a basic computational entity. Both are named in honor of the English...

  • Unorganized machine

Further reading

  • Gleick, James, The Information: A History, A Theory, A Flood
    The Information: A History, a Theory, a Flood
    The Information: A History, a Theory, a Flood is a book by science history writer James Gleick, author of Chaos: Making a New Science. It covers the genesis of our current information age. The Information has also been published in ebook formats by Fourth Estate and Random House, and as an...

    , New York: Pantheon, 2011, ISBN 9780375423727
  • Leavitt, David, The Man Who Knew Too Much: Alan Turing and the Invention of the Computer, W. W. Norton, 2006

External links



  • Alan Turing RKBExplorer
  • Alan Turing Year
  • CiE 2012: Turing Centenary Conference
  • Visual Turing
  • Turing Machine calculators at Wolfram Alpha
    Wolfram Alpha
    Wolfram Alpha is an answer-engine developed by Wolfram Research. It is an online service that answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer as a search engine might...

  • Alan Turing site maintained by Andrew Hodges
    Andrew Hodges
    Andrew Hodges is a mathematician, an author and a pioneer of the gay liberation movement of the 1970s.For the past decades , Hodges has focused his research activities on the twistor theory — the new approach to the problems of fundamental physics pioneered by the mathematician Roger...

     including a short biography
  • AlanTuring.net – Turing Archive for the History of Computing by Jack Copeland
    Jack Copeland
    Brian Jack Copeland is Professor of Philosophy at the University of Canterbury, Christchurch, New Zealand.Copeland received a BPhil and DPhil from the University of Oxford in philosophy, where he undertook research on modal and non-classical logic.He is the Director of the Turing Archive for the...

  • The Turing Archive – contains scans of some unpublished documents and material from the Kings College, Cambridge archive
  • Sherborne School Archives – holds papers relating to Alan Turing's time at Sherborne School
  • Alan Turing plaques recorded on openplaques.org

Papers

  • An extensive list of Turing's papers, reports and lectures, plus translated versions and collections BibNetWiki
  • Oral history interview with Donald W. Davies, Charles Babbage Institute
    Charles Babbage Institute
    The Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

    , University of Minnesota; Davies describes computer projects at the U.K. National Physical Laboratory, from the 1947 design work of Alan Turing to the development of the two ACE computers
  • Oral history interview with Nicholas C. Metropolis, Charles Babbage Institute
    Charles Babbage Institute
    The Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

    , University of Minnesota. Metropolis was the first director of computing services at Los Alamos National Laboratory
    Los Alamos National Laboratory
    Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

    ; topics include the relationship between Alan Turing and John von Neumann
    John von Neumann
    John von Neumann was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including set theory, functional analysis, quantum mechanics, ergodic theory, geometry, fluid dynamics, economics and game theory, computer science, numerical analysis,...