Alan Turing: Life and Accomplishments

• Alan Mathison Turing (1912-1954) was an influential English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist.
• Turing formalized the concepts of algorithm and computation with the Turing machine.
• The Turing Machine is a model of a general-purpose computer.
• He is widely considered the father of theoretical computer science.

Early Life and Education

• Born in London and raised in southern England.
• Graduated from King's College, Cambridge.
• Earned a doctorate from Princeton University in 1938.

World War II and Codebreaking

• Turing worked at Bletchley Park, Britain's codebreaking center during World War II.
• He led Hut 8, which was responsible for German naval cryptanalysis.
• He improved the Polish "bomba" method to break German Enigma ciphers.
• His work was crucial in deciphering intercepted messages that enabled Allied victories.

Post-War Contributions

• At the National Physical Laboratory, he designed the Automatic Computing Engine (ACE), which was one of the first designs for a stored-program computer.
• He joined Max Newman's Computing Machine Laboratory at the Victoria University of Manchester in 1948.
• There, he helped develop the Manchester computers.
• He wrote about the chemical basis of morphogenesis.
• He predicted oscillating chemical reactions like the Belousov–Zhabotinsky reaction.

Lack of Recognition and Prosecution

• Turing's work was largely unacknowledged during his lifetime due to the Official Secrets Act.
• In 1952, he was prosecuted for homosexual acts, which were illegal in the UK at the time.
• He underwent hormone treatment ("chemical castration") as an alternative to prison.

Death and Apology

• Turing died on June 7, 1954, from cyanide poisoning at age 41.
• An inquest ruled his death as suicide, though accidental poisoning is also possible.
• In 2009, British Prime Minister Gordon Brown issued a public apology for the appalling way Turing was treated.
• Queen Elizabeth II granted Turing a pardon in 2013.

Legacy

• The "Alan Turing law" is a 2017 UK law that retroactively pardoned men cautioned or convicted under historical anti-homosexuality laws.
• Turing's extensive legacy in mathematics and computing is widely recognized.
• His portrait is on the Bank of England £50 note (released June 23, 2021).

Family Background and Early Years

• Born in Maida Vale, London, while his father was with the Indian Civil Service (ICS).
• His mother was Ethel Sara Turing (née Stoney), from an Anglo-Irish gentry family.
• Alan had one elder brother, John Ferrier Turing.
• His parents traveled between the United Kingdom and India, leaving Alan and his brother with a retired Army couple.

Education

• Educated at Hazelhurst Preparatory School and Sherborne School.
• He cycled 60 miles (97 km) from Southampton to Sherborne to attend the first day of term during the 1926 General Strike.
• Alan's interest in math and science conflicted with the classical education preferred by some teachers.

Christopher Morcom

• At Sherborne, he befriended Christopher Collan Morcom (1911–1930), considered Turing's first love.
• Morcom's death from bovine tuberculosis greatly affected Turing.
• Turing worked harder on science and mathematics, interests he shared with Morcom, to cope with his sadness.
• He maintained contact with Morcom's mother, Frances Isobel Morcom, for years.

Cambridge and Early Mathematical Work

• Turing received a scholarship to study at King's College, Cambridge.
• He earned first-class honors in mathematics.
• Turing's dissertation proved a version of the central limit theorem.
• Published his first paper, "Equivalence of left and right almost periodicity", in 1935.
• Elected a Fellow of King's College.

"On Computable Numbers, with an Application to the Entscheidungsproblem"

• Reformulated Kurt Gödel's theorems on the limits of proof and computation.
• He replaced Gödel's formal language with Turing machines.
• The "universal computing machine" could perform any mathematical computation representable as an algorithm.
• There was no solution to the decision problem because the halting problem for Turing machines is undecidable.
• John von Neumann said that the central concept of the modern computer was due to Turing's paper.

Princeton University

• Studied under Alonzo Church at Princeton University from 1936 to 1938.
• Obtained a PhD in Mathematics.
• His dissertation introduced ordinal logic and relative computing.

Return to Cambridge and Wittgenstein

• Attended lectures by Ludwig Wittgenstein on the foundations of mathematics.
• Turing and Wittgenstein debated, with Turing defending formalism.

Cryptanalysis at Bletchley Park

• Turing joined the Government Code and Cypher School (GC&CS) in 1938.
• Worked on cryptanalysis of the Enigma cipher machine.
• Specified the bombe, an electromechanical device to break Enigma.
• The bombe was an improvement on the Polish Bomba.
• He deduced the indicator procedure used by the German navy.
• Developed Banburismus, a statistical procedure for more efficient use of the bombes.
• He developed Turingery, a method for working out the cam settings of the wheels of the Lorenz SZ 40/42 (Tunny) cipher machine.
• Developed a portable secure voice scrambler codenamed Delilah with assistance from REME officer Donald Bayley.
• He wrote two papers discussing mathematical approaches, titled The Applications of Probability to Cryptography and Paper on Statistics of Repetitions.
• Turing's eccentricities included wearing a gas mask to avoid hay fever and chaining his mug to the radiator.
• He was Officer of the Order of the British Empire (OBE) in 1946.
• By late 1941 Turing and fellow cryptanalysts Gordon Welchman, Hugh Alexander and Stuart Milner-Barry wrote directly to Winston Churchill to address limited staff and bombes, receiving extreme priority shortly after.

Naval Enigma and US Collaboration

• Turing solved the essential part of the German naval Enigma indicator system.
• He traveled to the United States in 1942 to work with the US Navy on naval Enigma and bombe construction.
• He helped Bell Labs develop secure speech devices.
• He was unimpressed with the American bombe design.
• Hugh Alexander officially assumed the role of head of Hut 8 in 1943, while Turing became a general consultant for cryptanalysis at Bletchley Park.
• Turingery was used against the Lorenz cipher messages.

Secure Voice Communications

• Turing pursued the idea of electronic enciphering of speech.
• He moved to Hanslope Park to work on secure voice communications.
• Delilah, a portable secure voice communications machine, was developed but not adopted.

Post-War Computing and the ACE

• Turing designed the Automatic Computing Engine (ACE) at the National Physical Laboratory (NPL) (1945-1947).
• Presented the first detailed design of a stored-program computer in 1946.
• He returned to Cambridge for a sabbatical year and produced "Intelligent Machinery".
• He met Konrad Zuse in Göttingen in 1947.

Turochamp and the Turing Test

• In 1948, Turing began writing a chess program ("Turochamp").
• He could not implement it on a Ferranti Mark 1.
• Turing manually executed the program on a chessboard, and the program "played a recognizable game of chess."
• The Turing test contributed to the debate regarding artificial intelligence.

Mathematical Biology and Morphogenesis

• Turing turned to mathematical biology in 1951.
• "The Chemical Basis of Morphogenesis" was published in 1952.
• A reaction–diffusion system could account for the main phenomena of morphogenesis.
• The work remains relevant and is considered a seminal piece in mathematical biology.
• James Murray used Turing's paper to explain spots and stripes on cat fur.

Silver Bars

• Turing bought and buried two silver bars (3,200 oz) to protect his savings during the 1940s.
• He was unable to recover them because he could not break his own code describing their location.

Engagement to Joan Clarke

• In 1941, Turing proposed marriage to Joan Clarke, a fellow mathematician, but the engagement was short-lived.
• Alan admitted his homosexuality to her, and Turing broke off the engagement.

Gross Indecency Conviction

• In 1951, Turing met Arnold Murray, he was 19.
• On January 23 Turing's house was burgled after his relationship progressed with Murray, Turing reported the crime.
• Turing was charged with "gross indecency" for homosexual acts.
• He accepted probation conditioned on "chemical castration" and the feminization of his body was continued for the course of one year.
• His security clearance was revoked, barring him from cryptographic consultancy.
• Turing was denied entry into the United States after his conviction in 1952.
• While visiting Norway, authorities intercepted and deported Kjell Carlson before meeting in the UK
• Turing began consulting psychiatrist Dr. Franz Greenbaum, with whom Turing and Greenbaum got on well with.

Death and Inquest

• Turing died on June 7, 1954, from cyanide poisoning.
• The inquest ruled the death as suicide.
• His remains were cremated in Woking Crematorium and his ashes were scattered in the gardens of the crematorium.
• Turing's mother never accepted the suicide verdict.

Alternative Explanations for Death

• Jack Copeland suggested accidental inhalation of cyanide fumes from a gold-plating apparatus.
• Turing's autopsy findings were more consistent with inhalation.
• Andrew Hodges theorized a possible reenactment of a scene from Snow White.
• A fortune-teller may have caused Turing's depressed mood before his death.

Apology and Pardon

• A petition urged the British government to apologize for Turing's prosecution.
• Prime Minister Gordon Brown apologized in 2009, calling Turing's treatment "appalling."
• A petition requested a pardon for Turing's conviction, which was initially discouraged.
• John Leech campaigned for the pardon in Parliament.
• Queen Elizabeth II signed a pardon in 2013.

Alan Turing Law

• The "Alan Turing law" is the informal term for the Policing and Crime Act 2017 in the UK.
• It retroactively pardoned men cautioned or convicted under historical anti-homosexuality legislation.
• Ben Wallace suggested honoring Turing with a statue in Trafalgar Square in 2023.

Churchill Myth

• There is no documentary evidence that Winston Churchill said Turing made the single biggest contribution to Allied victory.

Test your knowledge of Alan Turing's life, from his birth and education to his pivotal role in World War II and his lasting impact on computer science. This quiz explores key events and achievements of this influential figure.