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Alan Turing

2007 Schools Wikipedia Selection. Related subjects: Mathematicians

   Alan Mathison Turing, OBE ( June 23, 1912 – June 7, 1954), was an
   English mathematician, logician, and cryptographer. Turing is often
   considered to be the father of modern computer science.

   Turing provided an influential formalisation of the concept of the
   algorithm and computation with the Turing machine, formulating the now
   widely accepted "Turing" version of the Church–Turing thesis, namely
   that any practical computing model has either the equivalent or a
   subset of the capabilities of a Turing machine. With the Turing test,
   he made a significant and characteristically provocative contribution
   to the debate regarding artificial intelligence: whether it will ever
   be possible to say that a machine is conscious and can think. During
   World War II, Turing worked at Bletchley Park, Britain's codebreaking
   centre, and was for a time head of Hut 8, the section responsible for
   German Naval cryptanalysis. He devised a number of techniques for
   breaking German ciphers, including the method of the bombe, an
   electromechanical machine which could find settings for the Enigma
   machine.

   After the war, he worked at the National Physical Laboratory, creating
   one of the first designs for a stored-program computer, although it was
   never actually built. In 1947 he moved to the University of Manchester
   to work, largely on software, on the Manchester Mark I then emerging as
   one of the world's earliest true computers.

   In 1952, Turing was convicted of "acts of gross indecency" after
   admitting to a sexual relationship with a man in Manchester. He was
   placed on probation and required to undergo hormone therapy.

   Turing died after eating an apple laced with cyanide in 1954, sixteen
   days short of his 42nd birthday. His death is regarded by most as an
   act of suicide.

Childhood and youth

   Turing was conceived in 1911 in Chatrapur, India. His father, Julius
   Mathison Turing, was a member of the Indian civil service. Julius and
   wife Ethel (née Stoney) wanted Alan to be brought up in England, so
   they returned to Paddington, London, where Alan Turing was born June
   23, 1912, as recorded by a blue plaque on the outside of the building,
   now the Colonnade Hotel. His father's civil service commission was
   still active, and during Turing's childhood years his parents travelled
   between Guildford, England and India, leaving their two sons to stay
   with friends in England, rather than risk their health in the British
   colony. Very early in life, Turing showed signs of the genius he was to
   display more prominently later. He is said to have taught himself to
   read in three weeks, and to have shown an early affinity for numbers
   and puzzles.

   His parents enrolled him at St. Michael's, a day school, at the age of
   six. The headmistress recognized his genius early on, as did many of
   his subsequent educators. In 1926, at the age of 14, he went on to
   Sherborne School in Dorset. His first day of term coincided with a
   general strike in England, and so determined was he to attend his first
   day that he rode his bike unaccompanied over sixty miles from
   Southampton to school, stopping overnight at an inn — a feat reported
   in the local press.

   Turing's natural inclination toward mathematics and science did not
   earn him respect with the teachers at Sherborne, a famous and expensive
   public school (a British private school with charitable status), whose
   definition of education placed more emphasis on the classics. His
   headmaster wrote to his parents: "I hope he will not fall between two
   schools. 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. In 1928, aged sixteen, Turing encountered
   Albert Einstein's work; not only did he grasp it, but he extrapolated
   Einstein's questioning of Newton's laws of motion from a text in which
   this was never made explicit.
   The computer room at King's is now named after Turing, who became a
   student there in 1931 and a Fellow in 1935.
   Enlarge
   The computer room at King's is now named after Turing, who became a
   student there in 1931 and a Fellow in 1935.

   Turing's hopes and ambitions at school were raised by his strong
   feelings for his friend Christopher Morcom, with whom he fell in love,
   though the feeling was not reciprocated. Morcom suddenly died 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 was heart-broken.

University and his work on computability

   Due to his unwillingness to work as hard on his classical studies as on
   science and mathematics, Turing failed to win a scholarship to Trinity
   College, Cambridge, and went on to the college of his second choice,
   King's College, Cambridge. He was an undergraduate from 1931 to 1934,
   graduating with a distinguished degree, and in 1935 was elected a
   Fellow at King's on the strength of a dissertation on the Gaussian
   error function.
   Alan Turing, on the steps of the bus, with members of the Walton
   Athletic Club, 1946.
   Enlarge
   Alan Turing, on the steps of the bus, with members of the Walton
   Athletic Club, 1946.

   In his momentous paper "On Computable Numbers, with an Application to
   the Entscheidungsproblem" (submitted on May 28, 1936), Turing
   reformulated Kurt Gödel's 1931 results on the limits of proof and
   computation, substituting Gödel's universal arithmetics-based formal
   language by what are now called Turing machines, formal and simple
   devices. He proved that such a machine would be capable of performing
   any conceivable mathematical problem if it were representable as an
   algorithm, even if no actual Turing machine would be likely to have
   practical applications, being much slower than alternatives.

   Turing machines are to this day the central object of study in theory
   of computation. He went on to prove that there was no solution to the
   Entscheidungsproblem by first showing that the halting problem for
   Turing machines is undecidable: it is not possible to decide
   algorithmically whether a given Turing machine will ever halt. While
   his proof was published subsequent to Alonzo Church's equivalent proof
   in respect to his lambda calculus, Turing's work 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. The paper also introduces the
   notion of definable numbers.

   Most of 1937 and 1938 he spent at Princeton University, studying under
   Alonzo Church. In 1938 he obtained his Ph.D. from Princeton; his
   dissertation introduced the notion of relative computing where Turing
   machines are augmented with so-called oracles, allowing a study of
   problems that cannot be solved by a Turing machine.

   Back in Cambridge in 1939, he attended lectures by Ludwig Wittgenstein
   about the foundations of mathematics. The two argued and disagreed,
   with Turing defending formalism and Wittgenstein arguing that
   mathematics is overvalued and does not discover any absolute truths.

Cryptanalysis

   Two cottages in the stable yard at Bletchley Park. Turing worked here
   from 1939–1940 until he moved to Hut 8.
   Enlarge
   Two cottages in the stable yard at Bletchley Park. Turing worked here
   from 1939–1940 until he moved to Hut 8.

   During World War II, Turing was a major participant in the efforts at
   Bletchley Park to break German ciphers. Building on cryptanalysis work
   carried out in Poland prior to the outbreak of war, he contributed
   several insights into breaking both the Enigma machine and the Lorenz
   SZ 40/42 (a teletype cipher attachment codenamed "Tunny" by the
   British), and was, for a time, head of Hut 8, the section responsible
   for reading German Naval signals.

   Since September 1938, Turing had been working part-time for the
   Government Code and Cypher School. Turing reported to Bletchley Park on
   4 September 1939, the day after Britain declared war on Germany.

The Turing-Welchman bombe

   Replica of a bombe machine
   Enlarge
   Replica of a bombe machine

   Within weeks of arriving at Bletchley Park, Turing had devised an
   electromechanical machine which could help break Enigma: the bombe,
   named after the Polish-designed bomba. The bombe, with an enhancement
   suggested by mathematician Gordon Welchman, became the primary tool
   used to read Enigma traffic.

   The bombe searched for the correct settings of the Enigma rotors, and
   required a suitable " crib": a piece of matching plaintext and
   ciphertext. For each possible setting of the rotors, 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. Over 200 bombes were in operation by the end of the war.

Hut 8 and Naval Enigma

   In December 1940, Turing solved the naval Enigma indicator system,
   which was more complex than the indicator systems used by the other
   services. Turing also invented a Bayesian statistical technique termed
   " Banburismus" to assist in breaking Naval Enigma. Banburismus could
   rule out certain orders of the Enigma rotors, reducing time needed to
   test settings on the bombes.

   In the spring of 1941, Turing proposed marriage to Hut 8 co-worker Joan
   Clarke, although the engagement was broken off by mutual agreement in
   the summer.

   In July 1942, Turing devised a technique termed Turingismus or
   Turingery for use against the Lorenz cipher. A frequent misconception
   is that Turing was a key figure in the design of the Colossus computer;
   this was not the case.

   Turing travelled to the United States in November 1942 and liaised with
   US Navy cryptanalysts on Naval Enigma and bombe construction in
   Washington, and assisted at Bell Labs with the development of secure
   speech devices. He returned to Bletchley Park in March 1943. During his
   absence, Hugh Alexander had 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.

   In the latter part of the war, teaching himself electronics at the same
   time, Turing undertook (assisted by engineer Donald Bayley) the design
   of a portable machine codenamed Delilah to allow secure voice
   communications. Intended for different applications, Delilah lacked
   capability for use with long-distance radio transmissions, and was
   completed too late to be used in the war. Though Turing demonstrated it
   to officials by encrypting/decrypting a recording of a Winston
   Churchill speech, Delilah was not adopted for use.

   In 1945, Turing was awarded the OBE for his wartime services, but his
   work remained secret until many years. A biography published by the
   Royal Society shortly after his death recorded:

          "Three remarkable papers written just before the war, on three
          diverse mathematical subjects, show the qualilty 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."

Early computers and the Turing Test

   Turing achieved world-class Marathon standards. His best time of 2
   hours, 46 minutes, 3 seconds, was only 11 minutes slower than the
   winner in the 1948 Olympic Games.
   Turing achieved world-class Marathon standards. His best time of 2
   hours, 46 minutes, 3 seconds, was only 11 minutes slower than the
   winner in the 1948 Olympic Games.

   From 1945 to 1947 he was at the National Physical Laboratory, where he
   worked on the design of the ACE (Automatic Computing Engine). He
   presented a paper on February 19, 1946, which was the first complete
   design of a stored-program computer in Britain. Although he succeeded
   in designing the ACE, there were 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, ACE was completed in his
   absence and executed its first program on May 10, 1950. In 1949 he
   became deputy director of the computing laboratory at the University of
   Manchester, and worked on software for one of the earliest true
   computers — the Manchester Mark I. During this time he continued to do
   more abstract work, and in " Computing machinery and intelligence"
   (Mind, October 1950), Turing addressed the problem of artificial
   intelligence, and proposed an experiment now known as the Turing test,
   an attempt to define a standard for a machine to be called "sentient".

   In 1948, Turing, working with his former undergraduate colleague, D.G.
   Champernowne, began writing a chess 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, although it is said that it
   won a game against Champernowne's wife.

Pattern formation and mathematical biology

   Turing worked from 1952 until his death in 1954 on mathematical
   biology, specifically morphogenesis. He published one paper on the
   subject called "The Chemical Basis of Morphogenesis" in 1952. His
   central interest in the field was understanding Fibonacci phyllotaxis,
   the existence of Fibonacci numbers in plant structures. He used
   reaction-diffusion equations which are now central to the field of
   pattern formation. Later papers went unpublished until 1992 when
   Collected Works of A.M. Turing was published.

Prosecution for homosexual acts and Turing's death

   Turing was a homosexual during a period when homosexual acts were
   illegal and homosexuality was regarded as a mental illness. In 1952,
   Arnold Murray, a 19-year-old recent acquaintance of his helped an
   accomplice to break into Turing's house, and Turing went to the police
   to report the crime. As a result of the police investigation, Turing
   acknowledged a sexual relationship with Murray, and they were charged
   with gross indecency under Section 11 of the Criminal Law Amendment Act
   of 1885. Turing was unrepentant and was convicted. He was given the
   choice between imprisonment and probation, conditional on him
   undergoing hormonal treatment designed to reduce libido. In order to
   avoid going to jail, he accepted the oestrogen hormone injections,
   which lasted for a year, with side effects including the development of
   breasts. His conviction led to a removal of his security clearance and
   prevented him from continuing consultancy for GCHQ on cryptographic
   matters.

   In 1954, he died of cyanide poisoning, apparently from a cyanide-laced
   apple he left half-eaten. The apple itself was never tested for
   contamination with cyanide, and cyanide poisoning as a cause of death
   was established by a post-mortem. Most believe that his death was
   intentional, and the death was ruled a suicide. It is rumoured that
   this method of self-poisoning was in tribute to Turing's beloved film
   Snow White and the Seven Dwarfs. His mother, however, strenuously
   argued that the ingestion was accidental due to his careless storage of
   laboratory chemicals. Friends of his have said that Turing may have
   killed himself in this ambiguous way quite deliberately, to give his
   mother some plausible deniability. The possibility of assassination has
   also been suggested, owing to Turing's involvement in the Secret
   Service and the perception of Turing as a security risk due to his
   homosexuality.

   In the book Zeroes and Ones, author Sadie Plant speculates that the
   rainbow Apple logo with a bite taken out of it was a homage to Turing.
   This is unlikely: firstly because Apple's original logo depicted Isaac
   Newton under an apple tree, so any connection to Turing was at most an
   afterthought; and secondly because Gilbert Baker's rainbow pride flag,
   a gay pride emblem, was designed two years after the Apple logo, making
   it unlikely that the logo was meant to have a gay theme. In his book
   iWoz, Steve Wozniak confirms that the naming of Apple was done when he
   and Steve Jobs passed an apple orchard while driving, and was not a
   tribute to Turing.

Posthumous recognition

   Since 1966, the Turing Award has been given annually by the Association
   for Computing Machinery to a person for technical contributions to the
   computing community. It is widely considered to be the computing
   world's equivalent to the Nobel Prize.

   Various tributes to Turing have been made in Manchester, the city where
   he worked towards the end of his life. In 1994 a stretch of the
   Manchester city inner ring road was named Alan Turing Way.
   Alan Turing memorial statue in Sackville Park
   Enlarge
   Alan Turing memorial statue in Sackville Park

   A statue of Turing was unveiled in Manchester on June 23, 2001. It is
   in Sackville Park, between the University of Manchester building on
   Whitworth Street and the Canal Street ' gay village'. A celebration of
   Turing's life and achievements arranged by the British Logic Colloquium
   and the British Society for the History of Mathematics was held at the
   on 5 June 2004 at the University of Manchester and the Alan Turing
   Institute was initiated in the university, that summer.

   On 23 June 1998, on what would have been Turing's 86th birthday, Andrew
   Hodges, his biographer, unveiled an official English Heritage Blue
   Plaque on his childhood home in Warrington Crescent, London, now the
   Colonnade hotel. To mark the 50th anniversary of his death, a memorial
   plaque was unveiled at his former residence, Hollymeade, in Wilmslow on
   June 7, 2004.
   Plaque marking Turing's home
   Enlarge
   Plaque marking Turing's home

   For his achievements in computing, various universities have honoured
   him. On October 28, 2004 a bronze statue of Alan Turing sculpted by
   John W. Mills was unveiled at the University of Surrey . The statue
   marks the 50th anniversary of Turing's death. It portrays Turing
   carrying his books across the campus. The Polytechnic University of
   Puerto Rico and Los Andes University of Bogotá, Colombia, both have
   computer laboratories named after Turing. The University of Texas at
   Austin has an honours computer science program named the Turing
   Scholars. Istanbul Bilgi University organizes an annual conference on
   the theory of computation called Turing Days. Carnegie Mellon
   University has a granite bench, situated in The Hornbostel Mall, with
   the name "Alan Turing" carved across the top, "Read" down the left leg,
   and "Write" down the other.

   The Boston GLBT pride organization named Turing their 2006 Honorary
   Grand Marshal

Turing biographies

     * Turing's mother, Sara Turing, who survived him by many years, wrote
       a biography of her son glorifying his life.
     * Andrew Hodges wrote a definitive biography Alan Turing: The Enigma
       in 1983 (see references below).
     * The play Breaking the Code by Hugh Whitemore is about the life and
       death of Turing. In the original West End and Broadway runs, the
       role of Turing was played by Derek Jacobi, who also played Turing
       in a 1996 television adaptation of the play.
     * Turing is examined in A Madman Dreams of Turing Machines by Janna
       Levin.
     * Leavitt, David (2005). The Man Who Knew Too Much: Alan Turing and
       the Invention of the Computer. New York: W. W. Norton. ISBN
       0-393-05236-2.

     * Code-Breaker, by Jim Holt is reviewed by the New Yorker here:
       http://www.newyorker.com/critics/books/?060206crbo_books

Turing in fiction

     * Physicist Janna Levin's novel A Madman Dreams of Turing Machines
       focuses on the lives of both Alan Turing and Kurt Gödel.
     * Turing appears as a character in Neal Stephenson's Cryptonomicon.
     * A young Alan Turing introduces the title character to Gödel's first
       incompleteness theorem in Apostolos Doxiadis's novel Uncle Petros
       and Goldbach's Conjecture.
     * In the 1989 Doctor Who serial The Curse of Fenric, the character of
       Dr. Judson is based on Turing. Turing himself is a narrator of the
       Doctor Who spin-off novel The Turing Test by Paul Leonard.
     * Greg Egan's novella, Oracle, is about an alternate universe version
       of Turing
     * In John Banville's The Untouchable, the character Alastair Sykes is
       modeled on Alan Turing.
     * In William Gibson's seminal science fiction novel "Neuromancer",
       the sinister body tasked with the regulation and suppression of
       Artificial Intelligences is called the "Turing Police".

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