Konrad Zuse
Konrad Zuse in 1992
Born	(1910-06-22)22 June 1910 Berlin, German Empire
Died	18 December 1995(1995-12-18) (aged 85) Hünfeld, Germany
Residence	Germany
Fields	Computer science
Institutions	Aerodynamic Research Institute
Alma mater	Technical University of Berlin
Known for	Z3, Z4 Plankalkül Calculating Space (cf. digital physics)
Notable awards	Werner von Siemens Ring in 1964, Harry H. Goode Memorial Award in 1965 (together with George Stibitz), Great Cross of Merit in 1972 Computer History Museum Fellow Award in 1999 - weblink

Konrad Zuse (German pronunciation: [ˈkɔnʁat ˈtsuːzə]; 1910–1995) was a German civil engineer and computer pioneer. His greatest achievement was the world's first functional program-controlled Turing-complete computer, the Z3, which became operational in May 1941.

Zuse was also noted for the S2 computing machine, considered the first process-controlled computer. He founded one of the earliest computer businesses in 1941, producing the Z4, which became the world's first commercial computer. In 1946, he designed the first high-level programming language, Plankalkül.^[1] In 1969, Zuse suggested the concept of a computation-based universe in his book Rechnender Raum (Calculating Space).

Much of his early work was financed by his family and commerce, but after 1939 he was given resources by the Nazi German government.^[2] Due to World War II, Zuse's work went largely unnoticed in the United Kingdom and the United States. Possibly his first documented influence on a US company was IBM's option on his patents in 1946.

There is a replica of the Z3, as well as the original Z4, in the Deutsches Museum in Munich. The Deutsches Technikmuseum in Berlin has an exhibition devoted to Zuse, displaying twelve of his machines, including a replica of the Z1 and several of Zuse's paintings.

Pre-World War II work and the Z1[link]

Zuse Z1 replica in the German Museum of Technology in Berlin

Born in Berlin, Germany, on 22 June 1910, he moved with his family in 1912 to Braunsberg, East Prussia, where his father was a postal clerk. Zuse attended the Collegium Hosianum in Braunsberg. In 1923, the family moved to Hoyerswerda, where he passed his Abitur in 1928, qualifying him to enter university.

He enrolled in the Technische Hochschule Berlin-Charlottenburg and explored both engineering and architecture, but found them boring. Zuse then pursued civil engineering, graduating in 1935. For a time, he worked for the Ford Motor Company, using his considerable artistic skills in the design of advertisements.^[1] He started work as a design engineer at the Henschel aircraft factory in Berlin-Schönefeld. This required the performance of many routine calculations by hand, which he found mind-numbingly boring, leading him to dream of doing them by machine.

Working in his parents' apartment in 1936, his first attempt, called the Z1, was a floating point binary mechanical calculator with limited programmability, reading instructions from a perforated 35 mm film.^[1] In 1937, Zuse submitted two patents that anticipated a von Neumann architecture. He finished the Z1 in 1938. The Z1 contained some 30,000 metal parts and never worked well due to insufficient mechanical precision. The Z1 and its original blueprints were destroyed during World War II.

Between 1987 and 1989, Zuse recreated the Z1, suffering a heart attack midway through the project. It cost 800,000 DM, (approximately $500,000) and required four individuals (including Zuse) to assemble it. Funding for this retrocomputing project was provided by Siemens and a consortium of five companies.

The Z2, Z3, and Z4[link]

Statue of Zuse in Bad Hersfeld

Zuse completed his work entirely independently of other leading computer scientists and mathematicians of his day. Between 1936 and 1945, he was in near-total intellectual isolation.^[3] In 1939, Zuse was called to military service, where he was given the resources to ultimately build the Z2.^[2] The Z2 was a revised version of the Z1 using telephone relays. In 1941, he started a company, Zuse Apparatebau (Zuse Apparatus Construction), to manufacture his machines.^[4]

Improving on the basic Z2 machine, he built the Z3 in 1941. It was a binary 22-bit floating point calculator featuring programmability with loops but without conditional jumps, with memory and a calculation unit based on telephone relays. The telephone relays used in his machines were largely collected from discarded stock. Despite the absence of conditional jumps, the Z3 was a Turing complete computer (ignoring the fact that no physical computer can be truly Turing complete because of limited storage size). However, Turing-completeness was never considered by Zuse (who had practical applications in mind) and only demonstrated in 1998 (see History of computing hardware). The first electronic computer (though not programmable) was the Atanasoff machine developed at Iowa State University during 1939-41.

The Z3, the first fully operational electromechanical computer, was partially financed by German government-supported DVL (Deutsche Versuchsanstalt für Luftfahrt, i.e. German Research Institute for Aviation), which wanted their extensive calculations automated. A request by his co-worker Helmut Schreyer — who had helped Zuse build the Z3 prototype in 1938^[5] — for government funding for an electronic successor to the Z3 was denied as "strategically unimportant".

In 1937, Schreyer had advised Zuse to use vacuum tubes as switching elements; Zuse at this time considered it a crazy idea ("Schnapsidee" in his own words). Zuse's company (with the Z1, Z2 and Z3) was destroyed in 1945 by an Allied air attack. The partially finished, relay-based Z4, which Zuse had begun constructing in 1942,^[6] had been moved to a safe location earlier. Work on the Z4 could not continue in the extreme privation of post-war Germany, and it was not until 1949 that he was able to resume work on it. He showed it to the mathematician Eduard Stiefel of the Swiss Federal Institute of Technology Zurich (Eidgenössische Technische Hochschule (ETH) Zürich) who ordered one in 1950. On 8 November 1949, Zuse KG was founded. The Z4 was delivered to ETH Zurich on 12 July 1950, and proved very reliable.^[1]

While Zuse never became a member of the Nazi Party, he is not known to have expressed any doubts or qualms about working for the Nazi war effort. Much later, he suggested that in modern times, the best scientists and engineers usually have to choose between either doing their work for more or less questionable business and military interests in a Faustian bargain, or not pursuing their line of work at all.^[7]

S1 and S2[link]

In 1940, the German government began funding him through the Aerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute, forerunner of the DLR),^[8] which used his work for the production of glide bombs. Zuse built the S1 and S2 computing machines, which were special purpose devices which computed aerodynamic corrections to the wings of radio-controlled flying bombs. The S2 featured an integrated analog-to-digital converter under program control, making it the first process-controlled computer.^[6]

These machines contributed to the Henschel Werke Hs 293 and Hs 294 guided missiles developed by the German military between 1941 and 1945, which were the precursors to the modern cruise missile.^[6][9][10] The circuit design of the S1 was the predecessor of Zuse's Z11.^[6] Zuse believed that these machines had been captured by occupying Soviet troops in 1945.^[6]

Plankalkül[link]

While working on his Z4 computer, Zuse realised that programming in machine code was too complicated. After the progress of the war induced him to flee Berlin for the rural Allgäu, where he could not do any hardware work, he designed the first high-level programming language, Plankalkül ("Plan Calculus"), in 1945/6. This was first published in 1948,^[1] although not in its entirety until 1972. It was a theoretical contribution, since the language was not implemented in his lifetime and did not directly influence subsequent early languages. Heinz Rutishauser, one of the inventors of ALGOL, wrote: "The very first attempt to devise an algorithmic language was undertaken in 1948 by K. Zuse. His notation was quite general, but the proposal never attained the consideration it deserved." No compiler or interpreter was available for Plankalkül until a team from the Free University of Berlin implemented one in 2000.

Marriage and family[link]

Konrad Zuse married Gisela Brandes in January 1945 - employing a carriage, himself dressed in tailcoat and top hat and with Gisela in a wedding veil, for Zuse attached importance to a "noble ceremony". Their son Horst, the first of five children, was born in November 1945.

Zuse the entrepreneur[link]

Zuse's workshop at Neukirchen (situation January 2010)

Magnetic drum storage inside a Z31 (which was first displayed in 1963).

In 1946, Zuse founded one of the earliest computer companies: the Zuse-Ingenieurbüro Hopferau. Capital was raised through ETH Zurich and an IBM option on Zuse's patents.

Zuse founded another company, Zuse KG in Haunetal-Neukirchen in 1949; in 1957 the company’s head office moved to Bad Hersfeld. The Z4 was finished and delivered to the ETH Zurich, Switzerland in September 1950. At that time, it was the only working computer in continental Europe, and the second computer in the world to be sold, only beaten by the BINAC, which never worked properly after it was delivered. Other computers, all numbered with a leading Z, up to Z43,^[11] were built by Zuse and his company. Notable are the Z11, which was sold to the optics industry and to universities, and the Z22, the first computer with a memory based on magnetic storage.^[12]

By 1967, the Zuse KG had built a total of 251 computers. Due to financial problems, the company was then sold to Siemens.

[edit] Calculating Space

In 1967, Zuse also suggested that the universe itself is running on a cellular automaton or similar computational structure (digital physics); in 1969, he published the book Rechnender Raum (translated into English as Calculating Space). This idea has attracted a lot of attention, since there is no physical evidence against Zuse's thesis. Edward Fredkin (1980s), Jürgen Schmidhuber (1990s), Stephen Wolfram (A New Kind of Science) and others have expanded on it.

After he retired, he focused on his hobby, painting. Zuse died on 18 December 1995 in Hünfeld, Germany, near Fulda.

Awards and honours[link]

Zuse received several awards for his work:

• Werner von Siemens Ring in 1964 (together with Fritz Leonhardt and Walter Schottky)^[13]
• Harry H. Goode Memorial Award in 1965 (together with George Stibitz)
• Bundesverdienstkreuz in 1972 - Great Cross of Merit
• Computer History Museum Fellow Award in 1999^[14]

The Zuse Institute Berlin is named in his honour.

The Konrad Zuse Medal of the Gesellschaft für Informatik, and the Konrad Zuse Medal of the Zentralverband des Deutschen Baugewerbes (Central Association of German Construction), are both named after Zuse.

Zuse Year 2010[link]

The 100th anniversary of the birth of this computer pioneer was celebrated by exhibitions, lectures and workshops to remember his life and work and to bring attention to the importance of his invention to the digital age.^[15][16] The movie Tron: Legacy, which revolves around a world inside a computer system, features a character named Zuse, presumably in honour of Konrad Zuse.^{[citation needed]}

Literature[link]

• Konrad Zuse: The Computer – My Life, Springer Verlag, ISBN 3-540-56453-5, ISBN 0-387-56453-5
• Jürgen Alex, Hermann Flessner, Wilhelm Mons, Horst Zuse: Konrad Zuse: Der Vater des Computers. Parzeller, Fulda 2000, ISBN 3-7900-0317-4
• Raul Rojas (Hrsg.): Die Rechenmaschinen von Konrad Zuse. Springer, Berlin 1998, ISBN 3-540-63461-4.
• Jürgen Alex: Wege und Irrwege des Konrad Zuse. In: Spektrum der Wissenschaft (dt. Ausgabe von Scientific American) 1/1997, ISSN 0170-2971.
• Hadwig Dorsch: Der erste Computer. Konrad Zuses Z1 – Berlin 1936. Beginn und Entwicklung einer technischen Revolution. Mit Beiträgen von Konrad Zuse und Otto Lührs. Museum für Verkehr und Technik, Berlin 1989.
• Clemens Kieser: „Ich bin zu faul zum Rechnen“ – Konrad Zuses Computer Z22 im Zentrum für Kunst und Medientechnologie Karlsruhe. In: Denkmalpflege in Baden-Württemberg, 4/34/2005, Esslingen am Neckar, S. 180-184, ISSN 0342-0027.
• Arno Peters: Was ist und wie verwirklicht sich Computer-Sozialismus: Gespräche mit Konrad Zuse. Verlag Neues Leben, Berlin 2000, ISBN 3-355-01510-5.
• Paul Janositz: Informatik und Konrad Zuse: Der Pionier des Computerbaus in Europa – Das verkannte Genie aus Adlershof. In: Der Tagesspiegel Nr. 19127, Berlin, 9. März 2006, Beilage Seite B3.
• Jürgen Alex: Zum Einfluß elementarer Sätze der mathematischen Logik bei Alfred Tarski auf die drei Computerkonzepte des Konrad Zuse. TU Chemnitz 2006.
• Jürgen Alex: Zur Entstehung des Computers – von Alfred Tarski zu Konrad Zuse. VDI-Verlag, Düsseldorf 2007, ISBN 978-3-18-150051-4, ISSN 0082-2361.
• Herbert Bruderer: Konrad Zuse und die Schweiz. Wer hat den Computer erfunden? Charles Babbage, Alan Turing und John von Neumann Oldenbourg Verlag, München 2012, XXVI, 224 Seiten, ISBN 978-3-486-71366-4

See also[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Konrad Zuse

Wikiquote has a collection of quotations related to: Konrad Zuse

• Konrad Zuse Internet Archive
• The Life and Work of Konrad Zuse – By Prof. Horst Zuse (K. Zuse's son); an extensive and well-written historical account
• MacTutor biography
• Technical University of Berlin
• Free University of Berlin
• Konrad Zuse and his computers, from Technische Universität Berlin
• Konrad Zuse
• Konrad Zuse, inventor of first working programmable computer
• Zuse's thesis of digital physics and the computable universe
• Deutsches Technikmuseum Berlin
• Konrad Zuse Museum Hoyerswerda
• Konrad Zuse and The Invention of the Computer
• Computermuseum Kiel Z11
• Computermuseum Kiel Z22
• Computermuseum Kiel Z25

Charles Babbage
Charles Babbage in 1860
Born	(1791-12-26)26 December 1791 London, England
Died	18 October 1871(1871-10-18) (aged 79) Marylebone, London, England
Nationality	English
Fields	Mathematics, analytical philosophy, computer science
Institutions	Trinity College, Cambridge
Alma mater	Peterhouse, Cambridge
Known for	Mathematics, computing
Signature

Charles Babbage, FRS (26 December 1791 – 18 October 1871)^[1] was an English mathematician, philosopher, inventor and mechanical engineer who originated the concept of a programmable computer.^[2] Considered a "father of the computer",^[3] Babbage is credited with inventing the first mechanical computer that eventually led to more complex designs.^[4]

Parts of his uncompleted mechanisms are on display in the London Science Museum. In 1991, a perfectly functioning difference engine was constructed from Babbage's original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked. Nine years later, the Science Museum completed the printer Babbage had designed for the difference engine.^[5]

Birth[link]

Babbage's birthplace is disputed, but he was most likely born at 44 Crosby Row, Walworth Road, London, England. A blue plaque on the junction of Larcom Street and Walworth Road commemorates the event.^[6]

His date of birth was given in his obituary in The Times as 26 December 1792. However after the obituary appeared, a nephew wrote to say that Charles Babbage was born one year earlier, in 1791. The parish register of St. Mary's Newington, London, shows that Babbage was baptised on 6 January 1792, supporting a birth year of 1791.^[7][8][9]

Babbage's father, Benjamin Babbage, was a banking partner of the Praeds who owned the Bitton Estate in Teignmouth. His mother was Betsy Plumleigh Teape. In 1808, the Babbage family moved into the old Rowdens house in East Teignmouth, and Benjamin Babbage became a warden of the nearby St. Michael's Church.

Education[link]

Wikisource has original text related to this article: The Times/The Late Mr. Charles Babbage, F.R.S.

The Illustrated London News (4 November 1871).^[10]

His father's money allowed Charles to receive instruction from several schools and tutors during the course of his elementary education. Around the age of eight he was sent to a country school in Alphington near Exeter to recover from a life-threatening fever. His parents ordered that his "brain was not to be taxed too much " and Babbage felt that "this great idleness may have led to some of my childish reasonings." For a short time he attended King Edward VI Grammar School in Totnes, South Devon, but his health forced him back to private tutors for a time.^[11] He then joined a 30-student Holmwood academy, in Baker Street, Enfield, Middlesex under the Reverend Stephen Freeman. The academy had a well-stocked library that prompted Babbage's love of mathematics. He studied with two more private tutors after leaving the academy. Of the first, a clergyman near Cambridge, Babbage said, "I fear I did not derive from it all the advantages that I might have done."^{[citation needed]} The second was an Oxford tutor from whom Babbage learned enough of the Classics to be accepted to Cambridge.

Babbage arrived at Trinity College, Cambridge in October 1810.^[12] He had read extensively in Leibniz, Joseph Louis Lagrange, Thomas Simpson, and Lacroix and was seriously disappointed in the mathematical instruction available at Cambridge. In response, he, John Herschel, George Peacock, and several other friends formed the Analytical Society in 1812. Babbage, Herschel, and Peacock were also close friends with future judge and patron of science Edward Ryan. Babbage and Ryan married two sisters.^[13] As a student, Babbage was also a member of other societies such as the Ghost Club, concerned with investigating supernatural phenomena, and the Extractors Club, dedicated to liberating its members from the madhouse, should any be committed to one.^[14][15]

In 1812 Babbage transferred to Peterhouse, Cambridge.^[12] He was the top mathematician at Peterhouse, but did not graduate with honours. He instead received an honorary degree without examination in 1814.

Marriage, family, death[link]

Grave of Charles Babbage at Kensal Green Cemetery

On 25 July 1814, Babbage married Georgiana Whitmore at St. Michael's Church in Teignmouth, Devon. The couple lived at Dudmaston Hall,^[16] Shropshire (where Babbage engineered the central heating system), before moving to 5 Devonshire Street, Portland Place, London.

Charles and Georgiana had eight children,^[17] but only four — Benjamin Herschel, Georgiana Whitmore, Dugald Bromhead and Henry Prevost — survived childhood. Charles' wife Georgiana died in Worcester on 1 September 1827, the same year as his father, their second son (also named Charles) and their newborn son Alexander. His subsequent decision to spend a year travelling on the Continent incurred a delay in his machines' construction.

Charles Babbage died at the age of 79 on 18 October 1871, and was buried in London's Kensal Green Cemetery. According to Horsley, Babbage died "of renal inadequacy, secondary to cystitis."^[18] In 1983 the autopsy report for Charles Babbage was discovered and later published by his great-great-grandson.^[19][20] A copy of the original is also available.^[21] Half of Babbage's brain is preserved at the Hunterian Museum in the Royal College of Surgeons in London.^[22] The other half of Babbage's brain is on display in the Science Museum, London.^[23]

His youngest son, Henry Prevost Babbage (1824–1918), went on to create six working difference engines based on his father's designs,^[24] one of which was sent to Harvard University where it was later discovered by Howard H. Aiken, pioneer of the Harvard Mark I. Henry Prevost's 1910 Analytical Engine Mill, previously on display at Dudmaston Hall, is now on display at the Science Museum.^[25]

Design of computers[link]

Part of Babbage's difference engine (#1), assembled after his death by Babbage's son, using parts found in his laboratory

Babbage's machines were among the first mechanical computers, although they were not actually completed, largely because of funding problems and personality issues. He directed the building of some steam-powered machines that achieved some success, suggesting that calculations could be mechanised. Although Babbage's machines were mechanical and unwieldy, their basic architecture was very similar to a modern computer. The data and program memory were separated, operation was instruction-based, the control unit could make conditional jumps, and the machine had a separate I/O unit. For more than ten years he received government funding for his project, which amounted to £17,000.00, but eventually the Treasury lost confidence in Babbage.^[26]

Difference engine[link]

The Science Museum's Difference Engine #2, built from Babbage's design

In Babbage's time, numerical tables were calculated by humans who were called 'computers', meaning "one who computes", much as a conductor is "one who conducts". At Cambridge, he saw the high error-rate of this human-driven process and started his life's work of trying to calculate the tables mechanically. He began in 1822 with what he called the difference engine, made to compute values of polynomial functions. Unlike similar efforts of the time, Babbage's difference engine was created to calculate a series of values automatically. By using the method of finite differences, it was possible to avoid the need for multiplication and division.

At the beginning of the 1820s, Babbage worked on a prototype of his first difference engine. Some parts of it still survive in the Museum of the History of Science in Oxford.^[27] This prototype evolved into the "first difference engine." It remained unfinished and the completed fragment is located at the Science Museum in London. This first difference engine would have been composed of around 25,000 parts, weigh fifteen tons (13,600 kg), and would have been 8 ft (2.4 m) tall. Although Babbage received ample funding for the project, it was never completed. He later designed an improved version,"Difference Engine No. 2", which was not constructed until 1989–91, using his plans and 19th century manufacturing tolerances. It performed its first calculation at the London Science Museum returning results to 31 digits, far more than the average modern pocket calculator.

Completed models[link]

The London Science Museum has constructed two Difference Engines according to Babbage's plans for the Difference Engine No 2. One is owned by the museum. The other, owned by the technology multimillionaire Nathan Myhrvold, went on exhibition at the Computer History Museum^[28] in Mountain View, California on 10 May 2008.^[29] The two models that have been constructed are not replicas; until the assembly of the first Difference Engine No. 2 by the London Science Museum, no model of it existed.

Analytical Engine[link]

Soon after the attempt at making the difference engine crumbled, Babbage started designing a different, more complex machine called the Analytical Engine. The engine is not a single physical machine but a succession of designs that he tinkered with until his death in 1871. The main difference between the two engines is that the Analytical Engine could be programmed using punched cards. He realised that programs could be put on these cards so the designer had only to create the program initially and then put the cards in the machine and let it run. The analytical engine would have used loops of Jacquard's punched cards to control a mechanical calculator, which could formulate results based on the results of preceding computations. This machine was also intended to employ several features subsequently used in modern computers, including sequential control, branching and looping and would have been the first mechanical device to be Turing-complete.

Ada Lovelace, who corresponded with Babbage during his development of the Analytical Engine, is credited with developing an algorithm for the Analytical Engine to calculate a sequence of Bernoulli numbers. Although there is disagreement over how much of the ideas were Lovelace's own, she is often described as the first computer programmer.^[30]

In 2011, researchers in Britain embarked on a multimillion-pound project, "Plan 28", to construct Babbage's Analytical Engine. Since Babbage's plans were continually being refined and were never completed, they will engage the public in the project and crowd-source the analysis of what should be built.^[31] It would have the equivalent of 675 bytes of memory, and run at a clock speed of about 7 Hz. They hope to complete it by the 150th anniversary of Babbage's death, in 2021.^[32]

Modern adaptations[link]

While the abacus and mechanical calculator have been replaced by electronic calculators using microchips, the recent advances in MEMs and nanotechnology have led to recent high-tech experiments in mechanical computation. The benefits suggested include operation in high radiation or high temperature environments.^[33] These modern versions of mechanical computation were highlighted in the magazine The Economist in its special "end of the millennium" black cover issue in an article entitled "Babbage's Last Laugh".^[34]

Other accomplishments[link]

In 1824, Babbage won the Gold Medal of the Royal Astronomical Society "for his invention of an engine for calculating mathematical and astronomical tables". He was a founding member of the society and one of its oldest living members on his death in 1871.

From 1828 to 1839 Babbage was Lucasian Professor of Mathematics at Cambridge. He contributed largely to several scientific periodicals, and was instrumental in founding the Astronomical Society in 1820 and the Statistical Society in 1834. However, he dreamt of designing mechanical calculating machines.

I was sitting in the rooms of the Analytical Society, at Cambridge, my head leaning forward on the table in a kind of dreamy mood, with a table of logarithms lying open before me. Another member, coming into the room, and seeing me half asleep, called out, "Well, Babbage, what are you dreaming about?" to which I replied "I am thinking that all these tables" (pointing to the logarithms) "might be calculated by machinery".

Babbage was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1832.^[35] In 1837, responding to the Bridgewater Treatises, of which there were eight, he published his Ninth Bridgewater Treatise, On the Power, Wisdom and Goodness of God, as manifested in the Creation, putting forward the thesis that God had the omnipotence and foresight to create as a divine legislator, making laws (or programs) which then produced species at the appropriate times, rather than continually interfering with ad hoc miracles each time a new species was required. The book is a work of natural theology, and incorporates extracts from correspondence he had been having with John Herschel on the subject.

Babbage also achieved notable results in cryptography. He broke Vigenère's autokey cipher as well as the much weaker cipher that is called Vigenère cipher today. The autokey cipher was generally called "the undecipherable cipher", though owing to popular confusion, many thought that the weaker polyalphabetic cipher was the "undecipherable " one. Babbage's discovery was used to aid English military campaigns, and was not published until several years later; as a result, credit for the development was instead given to Friedrich Kasiski, a Prussian infantry officer, who made the same discovery some years after Babbage.^[36]

In 1838, Babbage invented the pilot (also called a cow-catcher), the metal frame attached to the front of locomotives that clears the tracks of obstacles.^[37] He also constructed a dynamometer car and performed several studies on Isambard Kingdom Brunel's Great Western Railway in about 1838.^[38] Babbage's eldest son, Benjamin Herschel Babbage, worked as an engineer for Brunel on the railways before emigrating to Australia in the 1850s.^[39]

Babbage also invented an ophthalmoscope, but although he gave it to a physician for testing it was forgotten, and the device only came into use after being independently invented by Hermann von Helmholtz.^[40]

Babbage twice stood for Parliament as a candidate for the borough of Finsbury. In 1832 he came in third among five candidates, but in 1834 he finished last among four.^[41][42][43]

In On the Economy of Machine and Manufacture, Babbage described what is now called the Babbage principle, which describes certain advantages with division of labour. Babbage noted that highly skilled—and thus generally highly paid—workers spend parts of their job performing tasks that are "below" their skill level. If the labour process can be divided among several workers, it is possible to assign only high-skill tasks to high-skill and high-cost workers and leave other working tasks to less-skilled and lower-paid workers, thereby cutting labour costs. This principle was criticised by Karl Marx who argued that it caused labour segregation and contributed to alienation. The Babbage principle is an inherent assumption in Frederick Winslow Taylor's scientific management.

Babbage made notable contributions in other areas as well. He assisted in establishing the modern postal system in England and compiled the first reliable actuarial tables.^{[citation needed]}

Views[link]

Charles Babbage's brain is on display at The Science Museum

Babbage once counted all the broken panes of glass of a factory, publishing in 1857 a "Table of the Relative Frequency of the Causes of Breakage of Plate Glass Windows": Of 464 broken panes, 14 were caused by "drunken men, women or boys".^[44][45][46]

Babbage's distaste for commoners ("the Mob") included writing "Observations of Street Nuisances" in 1864, as well as tallying up 165 "nuisances" over a period of 80 days. He especially hated street music, and in particular the music of organ grinders, against whom he railed in various venues. The following quotation is typical:

It is difficult to estimate the misery inflicted upon thousands of persons, and the absolute pecuniary penalty imposed upon multitudes of intellectual workers by the loss of their time, destroyed by organ-grinders and other similar nuisances.^[47]

In the 1860s, Babbage also took up the anti-hoop-rolling campaign. He blamed hoop-rolling boys for driving their iron hoops under horses' legs, with the result that the rider is thrown and very often the horse breaks a leg.^[48] Babbage achieved a certain notoriety in this matter, being denounced in debate in Commons in 1864 for "commencing a crusade against the popular game of tip-cat and the trundling of hoops."^[49]

Then Prime Minister, Sir Robert Peel offered Babbage a baronetcy, which Babbage refused on the grounds that he did not support the idea of hereditary peerage, an opinion he frequently expressed in his writings. His preferred life peerage was refused and as a result, neither was granted.^[50]

Supposed influence from Indian thought[link]

The discoveries of Babbage (as to a lesser extent Herschel, de Morgan and George Boole) have been seen by some as being influenced by Indian thought, in particular Indian logic.^[51] Mary Everest Boole claims that Babbage, along with Herschel was introduced to Indian thought in the 1820s by her uncle George Everest:

Some time about 1825, [Everest] came to England for two or three years, and made a fast and lifelong friendship with Herschel and with Babbage, who was then quite young. I would ask any fair-minded mathematician to read Babbage's Ninth Bridgewater Treatise and compare it with the works of his contemporaries in England; and then ask himself whence came the peculiar conception of the nature of miracle which underlies Babbage's ideas of Singular Points on Curves (Chap, viii) – from European Theology or Hindu Metaphysic? Oh! how the English clergy of that day hated Babbage's book!^[52]

Mary Boole also states:

Think what must have been the effect of the intense Hinduizing of three such men as Babbage, De Morgan, and George Boole on the mathematical atmosphere of 1830–1865. What share had it in generating the Vector Analysis and the mathematics by which investigations in physical science are now conducted?^[52]

Plaques and memorials[link]

• There is a green plaque commemorating the 40 years Babbage spent at 1 Dorset St, London.^[53]

Things named after Charles Babbage[link]

There have been a number of locations, institutions and others named after Babbage. They include:

• The Moon crater Babbage
• The Charles Babbage Institute, an information technology archive and research center at the University of Minnesota
• Babbage's, an American software retail store in the 1980s and 90s (it was later merged with other stores, into GameStop)
• The large Babbage lecture theatre at Cambridge University, used for undergraduate science lectures
• British Rail named a locomotive after him in the 1990s as part of a program of naming locomotives after famous and significant scientists
• The Babbage Building at the University of Plymouth, where the university's school of computing is based
• The IT Service of Cambridgeshire County Council was based in Babbage House on the Castle Park office complex up until December 2011.
• In Monk's Walk School, there is a block called "Babbage"
• In Chessington, in the Royal Borough of Kingston upon Thames, a road in a new housing development has been named Charles Babbage Close
• The Babbage programming language for GEC 4000 series minicomputers
• There is a Babbage Room at Totnes Museum, in Totnes where Babbage spent his youth
• "Babbage", The Economist's Science and Technology blog^[54]

In fiction[link]

Babbage frequently appears in steampunk works (the enumeration of which would be an exhausting effort), where he does build the Difference Engine, spurring on computer science in the Victorian Era.

Other fictional works in which Babbage appears include:

• Charles Babbage appears as a Great Thinker in the 2008 strategy video game Civilization Revolution.^[55]
• The 2008 short film Babbage shows Babbage at a dinner party

Publications[link]

Wikisource has original works written by or about: Charles Babbage

Wikimedia Commons has media related to: Charles Babbage

Wikisource has the text of the 1911 Encyclopædia Britannica article Babbage, Charles.

• Babbage, Charles (1826). A Comparative View of the Various Institutions for the Assurance of Lives. London: J. Mawman. http://books.google.com/?id=teGjS4XfpbMC&printsec=frontcover&dq=charles+babbage. 
• Babbage, Charles (1830). Reflections on the Decline of Science in England, and on Some of Its Causes. London: B. Fellowes. http://books.google.com/?id=3bgPAAAAMAAJ&printsec=frontcover&dq=charles+babbage. 
• Babbage, Charles (1835). On the Economy of Machinery and Manufactures (4 ed.). London: Charles Knight. http://books.google.ca/books?id=wUQeMa0MFnkC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false. 
• Babbage, Charles (1837). The Ninth Bridgewater Treatise, a Fragment. London: John Murray. http://books.google.com/?id=RlgEAAAAQAAJ&printsec=frontcover&dq=charles+babbage.  (reissued by Cambridge University Press 2009, ISBN 978-1-108-00000-0)
• Babbage, Charles (1841). Table of the Logarithms of the Natural Numbers from 1 to 108000. London: William Clowes and Sons. http://books.google.com/?id=teMGAAAAYAAJ&printsec=frontcover&dq=charles+babbage.  (the LOCOMAT site contains a reconstruction of this table)
• Babbage, Charles (1851). The Exposition of 1851. London: John Murray. http://books.google.com/?id=NZcBAAAAQAAJ&printsec=frontcover&dq=charles+babbage. 
• Babbage, Charles (1864). Passages from the Life of a Philosopher. London: Longman. http://books.google.com/?id=2T0AAAAAQAAJ&printsec=frontcover&dq=charles+babbage. 
• Babbage, Charles (1989). Hyman, Anthony. ed. Science and Reform: Selected Works of Charles Babbage. Cambridge University Press. ISBN 978-0-521-34311-4. http://books.google.com/books?id=0gZ7Bo2NnzAC. 

References[link]

External links[link]

Computer programming portal

Wikisource has original works written by or about: Charles Babbage

Wikiquote has a collection of quotations related to: Charles Babbage

• Babbage Science Museum, London. Description of Babbage's calculating machine projects and the Science Museum's study of Babbage's works, including modern reconstruction and model-building projects
• The Babbage Engine: Computer History Museum, Mountain View CA, USA. Multi-page account of Babbage, his engines and his associates, including a video of the Museum's functioning replica of the Difference Engine No 2 in action
• Charles Babbage A history at the School of Mathematics and Statistics,University of St Andrews Scotland.
• Mr. Charles Babbage: obituary from The Times (1871)
• The Babbage Pages
• Works by Charles Babbage at Project Gutenberg
• The Babbage Difference Engine: an overview of how it works
• "On a Method of Expressing by Signs the Action of Machinery", 1826. Original edition
• P1076 Archival material relating to Charles Babbage listed at the UK National Register of Archives
• Charles Babbage Institute: pages on "Who Was Charles Babbage?" including biographical note, description of Difference Engine No. 2, publications by Babbage, archival and published sources on Babbage, sources on Babbage and Ada Lovelace
• Babbage's Ballet by Ivor Guest, Ballet Magazine, 1997

Alan Mathison Turing, OBE, FRS ( /ˈtjʊərɪŋ/ TEWR-ing; 23 June 1912 – 7 June 1954), was an English mathematician, logician, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a significant role in the creation of the modern computer.^[1][2] Turing is widely considered to be the father of computer science and artificial intelligence.^[3]

During the Second World War, Turing worked for the Government Code and Cypher School (GCCS) at Bletchley Park, Britain's codebreaking centre. For a time he was 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 that could find settings for the Enigma machine.

After the war he worked at the National Physical Laboratory, where he created one of the first designs for a stored-program computer, the ACE. In 1948 Turing joined Max Newman's Computing Laboratory at Manchester University, where he assisted in the development of the Manchester computers^[4] and became interested in mathematical biology. He wrote a paper on the chemical basis of morphogenesis,^[5] and he predicted oscillating chemical reactions such as the Belousov–Zhabotinsky reaction, which were first observed in the 1960s.

Turing's homosexuality 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) as an alternative to prison. He died in 1954, just over two weeks before his 42nd birthday, from cyanide 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 Gordon Brown made an official public apology on behalf of the British government for the way in which Turing was treated after the war.^[6]

Childhood and youth[link]

Turing was conceived at Chhatrapur, Orissa, then part of British India.^[7][8] His father, Julius Mathison Turing, was a member of the Indian Civil Service. He and his wife Ethel Sara Stoney (1881–1976), daughter of Edward Waller Stoney, chief engineer of the Madras Railways, wanted their children to be brought up in England, so they returned to Maida Vale,^[9] London, where Turing was born on 23 June 1912, as recorded by a blue plaque on the outside of the house of his birth,^[10] later the Colonnade Hotel.^[7][11] 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, England^[12] 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 later to display prominently.^[13]

His parents enrolled him at St Michael's, a day school at 20 Charles Road, St Leonards-on-Sea, 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, a famous independent school in the market town of Sherborne in Dorset. His first day of term coincided with the 1926 General Strike in Britain, but so determined was he to attend his first day that he rode his bicycle unaccompanied more than 60 miles (97 km) from Southampton to school, stopping overnight at an inn.^[14]

King's College, Cambridge, where the computer room is named after Turing, who became a student there in 1931 and a Fellow in 1935

Turing's natural inclination toward mathematics and science did not earn him respect with some of the teachers at Sherborne, whose definition of education placed more emphasis on the classics. 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".^[15] 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 16, 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.^[16]

At Sherborne Turing formed a friendship with fellow pupil Christopher Morcom. This friendship, cut short by Morcom's death in February 1930 from complications of bovine tuberculosis (contracted after drinking infected cow's milk some years previously), would provide inspiration for Turing's future achievements.^{[17] [18]} Turing's religious faith was shattered by Morcom's death and he became an atheist. He adopted the conviction that all phenomena, including the workings of the human brain, must be materialistic,^[19] but he still believed in the survival of the spirit after death.^[20]

University and work on computability[link]

Alan Turing memorial statue in Sackville Park, Manchester

After Sherborne, Turing went to study at King's College, Cambridge. He was an undergraduate there from 1931 to 1934, graduating with first-class honours in Mathematics. In 1935, at the young age of 22, he was elected a fellow at King's on the strength of a dissertation in which he proved the central limit theorem,^[21] despite the fact that he had failed to find out that it had already been proved in 1922 by Jarl Waldemar Lindeberg.^[22]

In 1928, German mathematician David Hilbert had called attention to the Entscheidungsproblem (decision problem). In his momentous paper "On Computable Numbers, with an Application to the Entscheidungsproblem" (submitted on 28 May 1936 and delivered 12 November),^[23] Turing reformulated Kurt Gödel's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with what became known as Turing machines, formal and simple hypothetical devices. He proved that some such machine would be capable of performing any conceivable mathematical computation if it were representable as an algorithm. 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: in general, it is not possible to decide algorithmically, whether a given Turing machine will ever halt.

While his proof was published shortly after Alonzo Church's equivalent proof in respect of his lambda calculus, Turing was unaware of Church's work at the time that he developed it.^[24] Turing's approach is considerably more accessible and intuitive than Church's. It was also novel in its notion of a 'Universal Machine' (now known as a Universal Turing machine), with the idea that such a machine could perform the tasks of any other 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. In his memoirs Turing wrote that he was disappointed about the reception of this 1936 paper, which also introduced the notion of definable numbers, and that only two people had reacted – these being Heinrich Scholz and Richard Bevan Braithwaite.^{[citation needed]}

From September 1936 to July 1938 he spent most of his time at the Institute for Advanced Study, Princeton, New Jersey, studying under 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.^[25] In June 1938 he obtained his PhD from Princeton University; his dissertation (Systems of Logic Based on Ordinals^[26]) introduced the concept of ordinal logic and 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, he attended lectures by Ludwig Wittgenstein about the foundations of mathematics.^[27] The two argued and disagreed, with Turing defending formalism and Wittgenstein arguing that mathematics does not discover any absolute truths but rather invents them.^[28] He also started to work part-time with the Government Code and Cypher School (GCCS).

Cryptanalysis[link]

Two cottages in the stable yard at Bletchley Park. Turing worked here in 1939 and 1940, before moving to Hut 8.

During the Second World War, Turing was a leading participant in the breaking of German ciphers at Bletchley Park. The historian and wartime codebreaker Asa Briggs has said:

You needed exceptional talent, you needed genius at Bletchley and Turing's was that genius.^[29]

From September 1938, Turing had been working part-time with the Government Code and Cypher School (GCCS), the British code breaking organisation. He concentrated on Cryptanalysis of the Enigma, with Dilly Knox, a senior GCCS codebreaker.^[30] Soon after the July 1939 Warsaw meeting at which the Polish Cipher Bureau had provided the British and French with the details of the wiring of Enigma rotors and their method of decrypting Enigma messages, Turing and Knox started to work on a less fragile approach to the problem.^[31] The Polish method relied on an insecure indicator procedure that the Germans were likely to change, which they did in May 1940. Turing's approach was more general, using crib-based decryption for which he produced the initial functional specification of the bombe.

On 4 September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GCCS.^[32] Specifying the bombe was the first of five major cryptanalytical advances that Turing made during the war. The others were: deducing the indicator procedure used by the German navy; developing a statistical procedure for making much more efficient use of the bombes dubbed Banburismus; developing a procedure for working out the cam settings of the wheels of the Lorenz SZ 40/42 (Tunny) dubbed Turingery and, towards the end of the war, the development of a portable secure voice scrambler at Hanslope Park that was codenamed Delilah.

By using statistical techniques to optimise the trial of different possibilities in the code breaking process, Turing made an innovative contribution to the subject. He wrote two papers discussing mathematical approaches which were entitled Report on the applications of probability to cryptography^[33] and Paper on statistics of repetitions^[34] which were of such value to GCCS and its successor GCHQ, that they were not released to the UK National Archives until April 2012, shortly before the centenary of his birth. A GCHQ mathematician said at the time that the fact that the contents had been restricted for some 70 years demonstrated their importance.^[35]

Turing had something of a reputation for eccentricity at Bletchley Park. He was known to his colleagues as 'Prof' and his Treatise on Enigma was known as 'The Prof's Book'.^[36] 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.^[37]

While working at Bletchley, Turing, a talented long-distance runner, occasionally ran the 40 miles (64 km) to London when he was needed for high-level meetings,^[38] and he was capable of world-class marathon standards.^[39]

In 1945, Turing was awarded the OBE for his wartime services, but his work remained secret for many years.

Turing–Welchman bombe[link]

A complete and working replica of a bombe at the National Codes Centre at Bletchley Park

Within weeks of arriving at Bletchley Park,^[32] Turing had specified an electromechanical machine that could help break Enigma more effectively than the Polish bomba kryptologiczna, from which its name was derived. The bombe, with an enhancement suggested by mathematician Gordon Welchman, became one of the primary tools, and the major automated one, used to attack Enigma-enciphered messages.

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.^[40]

The bombe searched for possible correct settings used for an Enigma message (i.e. rotor order, rotor settings and plugboard settings), using a suitable crib: a fragment of probable plaintext. For each possible setting of the rotors (which had of the order of 10¹⁹ states, or 10²² for the four-rotor U-boat variant),^[41] 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 on to the next. Most of the possible settings would cause contradictions and be discarded, leaving only a few to be investigated in detail. The first bombe was installed on 18 March 1940.^[42] More than two hundred bombes were in operation by the end of the war.^[43]

Hut 8 and Naval Enigma[link]

Statue of Turing by Stephen Kettle at Bletchley Park, commissioned by the American philanthropist Sidney E Frank.^[44]

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".^[45] 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.^[45][46] That same night he also conceived of the idea of Banburismus, a sequential statistical technique (what Abraham Wald later called sequential analysis) 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".^[45] For this he invented a measure of weight of evidence that he called the Ban. Banburismus could rule out certain sequences 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 and cryptanalyst, 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.^[47]

Turing travelled to the United States in November 1942^[48] and worked with U.S. Navy cryptanalysts on Naval Enigma and bombe construction in Washington, visiting their Computing Machine Laboratory at Dayton, Ohio. His reaction to the American Bombe design was far from enthusiastic:

It seems a pity for them to go out of their way to build a machine to do all this stopping if it is not necessary. I am now converted to the extent of thinking that starting from scratch on the design of a Bombe, this method is about as good as our own. The American Bombe program was to produce 336 Bombes, one for each wheel order. I used to smile inwardly at the conception of test (of commutators) can hardly be considered conclusive as they were not testing for the bounce with electronic stop finding devices.^[49]

During this trip, he also assisted at Bell Labs with the development of secure speech devices.^[50]

He returned to Bletchley Park in March 1943. During his absence, Hugh Alexander 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 realized by the outside world.^[51]

Turingery[link]

In July 1942, Turing devised a technique termed Turingery (or jokingly Turingismus)^[52] for use against the Lorenz cipher messages produced by the Germans' new Geheimschreiber (secret writer) machine. This was a teleprinter rotor cipher attachment codenamed Tunny at Bletchley Park. Turingery was a method of wheel-breaking, i.e. a procedure for working out the cam settings of Tunny's wheels.^[53] He also introduced the Tunny team to Tommy Flowers who, under the guidance of Max Newman, went on to build the Colossus computer, the world's first programmable digital electronic computer, which replaced a simpler prior machine (the Heath Robinson), and whose superior speed allowed the statistical decryption techniques to be applied usefully to the messages.^[54] Some have mistakenly said that Turing was a key figure in the design of the Colossus computer. Turingery and the statistical approach of Banburismus undoubtedly fed into the thinking about cryptanalysis of the Lorenz cipher,^[55][56] but he was not directly involved in the Colossus development.^[57]

Secure speech device (Delilah)[link]

Following his work at Bell Labs in the US,^[58] Turing pursued the idea of electronic enciphering of speech in the telephone system, and in the latter part of the war, he moved to work for the Secret Service's Radio Security Service (later HMGCC) at Hanslope Park. There 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 communications machine codenamed Delilah.^[59] 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 and decrypting a recording of a Winston Churchill speech, Delilah was not adopted for use.^[60] Turing also consulted with Bell Labs on the development of SIGSALY, a secure voice system that was used in the later years of the war.

Early computers and the Turing test[link]

From 1945 to 1947 Turing lived in Richmond, London^[61] while he worked on the design of the ACE (Automatic Computing Engine) at the National Physical Laboratory (NPL). He presented a paper on 19 February 1946, which was the first detailed design of a stored-program computer.^[62] Von Neumann's incomplete First Draft of a Report on the EDVAC had predated Turing's paper, but it was much less detailed and, according to John R. Womersley, Superintendent of the NPL Mathematics Division, it "contains a number of ideas which are Dr. Turing’s own".^[63] 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 was built in his absence. It executed its first program on 10 May 1950. Although Turing's ACE was never built, a number of computers around the world owe a lot to it, for example, the English Electric DEUCE and the American Bendix G-15.

According to the memoirs of the German computer pioneer Heinz Billing from the Max Planck Institute for Physics, published by Genscher, Düsseldorf (1997), there was a meeting between Alan Turing and Konrad Zuse. It took place in Göttingen in 1947. The interrogation had the form of a colloquium. Participants were Womersley, Turing, Porter from England and a few German researchers like Zuse, Walther, and Billing. (For more details see Herbert Bruderer, Konrad Zuse und die Schweiz).

In 1948, he was appointed Reader in the Mathematics Department at the University of Manchester. In 1949, he became Deputy Director of the Computing Laboratory there, working on software for one of the earliest stored-program computers—the Manchester Mark 1. 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 which became known as the Turing test, an attempt to define a standard for a machine to be called "intelligent". The idea was that a computer could be said to "think" if a human interrogator could not tell it apart, through conversation, from a human being.^[64] 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 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, 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.^[65] The program lost to Turing's colleague Alick Glennie, although it is said that it won a game against Champernowne's wife.

His Turing test was a significant and characteristically provocative and lasting contribution to the debate regarding artificial intelligence, which continues after more than half a century.^[66]

He also invented the LU decomposition method in 1948, used today for solving matrix equations.^[67]

Pattern formation and mathematical biology[link]

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, putting forth the Turing hypothesis of pattern formation.^[68] 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 central to the field of pattern formation. 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.^[69]

Conviction for indecency[link]

Anthony Cave Brown's book, "C": The Secret Life of Sir Stewart Menzies, Spymaster to Winston Churchill, states:

Menzies had known that Turing was a practicing and aggressive homosexual; this had emerged soon after his employment at Bletchley. But since he caused no offence to his colleagues at Bletchley, and since he was perhaps the only man in Menzies's service who might have been called ‘indispensable,’ his services were retained... Early in 1944 a suspicion arose that he might have been the man responsible for molesting schoolboys at the main public library in Luton, a large industrial town not far from Bletchley. While no proceedings arose, it was decided that the need for good order and discipline required his removal — but not before he had done his finest work.^[70]

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.^[71]

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,^[72] and so both were charged with gross indecency under Section 11 of the Criminal Law Amendment Act 1885.^[73]

Turing was given a choice between imprisonment or probation conditional on his agreement to undergo hormonal treatment designed to reduce libido. He accepted chemical castration via oestrogen hormone injections.^[74]

Turing's conviction led to the removal of his security clearance, and barred him from continuing with his cryptographic consultancy for the Government Communications Headquarters (GCHQ), the UK signals intelligence agency that had evolved from GCCS in 1946. At the time, there was acute public anxiety about spies and homosexual entrapment by Soviet agents,^[75] because of the recent exposure of the first two members of the Cambridge Five, Guy Burgess and Donald Maclean, as KGB double agents. Turing was never accused of espionage but, as with all who had worked at Bletchley Park, was prevented from discussing his war work.^[76]

Death[link]

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,^[77] it is speculated that this was the means by which a fatal dose was delivered. An inquest determined that he had committed suicide, and he was cremated at Woking Crematorium on 12 June 1954.^[78] Turing's mother argued strenuously that the ingestion was accidental, caused by her son's careless storage of laboratory chemicals. Biographer Andrew Hodges suggests that Turing may have killed himself in an ambiguous way quite deliberately, to give his mother some plausible deniability.^[79] David Leavitt has suggested that Turing was re-enacting a scene from the 1937 film Snow White, his favourite fairy tale, pointing out that he took "an especially keen pleasure in the scene where the Wicked Witch immerses her apple in the poisonous brew."^[80]

Epitaph[link]

Hyperboloids of wondrous Light
Rolling for aye through Space and Time
Harbour those Waves which somehow Might

Play out God's holy pantomime^[81]

Recognition and tributes[link]

A Blue Plaque marking Turing's home at Wilmslow, Cheshire

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:^[1]

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 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 highest honour, equivalent to the Nobel Prize.^[82]

Breaking the Code is a 1986 play by Hugh Whitemore about Alan Turing. The play ran in London's West End 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 played Turing. The Broadway production was nominated for three Tony Awards including Best Actor in a Play, Best Featured Actor in a Play, and Best Direction of a Play, and for two Drama Desk Awards, for Best Actor and Best Featured Actor.

On 23 June 1998, on what would have been Turing's 86th birthday, Andrew Hodges, his biographer, unveiled an official English Heritage Blue Plaque at his birthplace and childhood home in Warrington Crescent, London, later the Colonnade Hotel.^[83][84] To mark the 50th anniversary of his death, a memorial plaque was unveiled on 7 June 2004 at his former residence, Hollymeade, in Wilmslow, Cheshire.^[85]

On 13 March 2000, Saint Vincent and the Grenadines issued a set of stamps 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 1 April 2003, Turing's work at Bletchley Park was named an IEEE Milestone.^[86] On 28 October 2004, a bronze statue of Alan Turing sculpted by John W. Mills was unveiled at the University of Surrey in Guildford, marking the 50th anniversary of Turing's death; it portrays him carrying his books across the campus.^[87] In 2006, Boston Pride named Turing their Honorary Grand Marshal.^[88]

Turing was one of four mathematicians examined in the 2008 BBC documentary entitled "Dangerous Knowledge".^[89] The Princeton Alumni Weekly named Turing the second most significant alumnus in the history of Princeton University, second only to President James Madison. 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 slate, it was sculpted by Stephen Kettle, having been commissioned by the late American billionaire Sidney Frank.^[90]

Turing has been honoured in various ways in Manchester, the city where he worked towards the end of his life. In 1994, a stretch of the A6010 road (the Manchester city intermediate ring road) was named "Alan Turing Way". Part of this road runs alongside the City of Manchester Stadium, where Manchester City play their games. A bridge carrying this road was widened, and carries the name Alan Turing Bridge. A statue of Turing was unveiled in Manchester on 23 June 2001. It is in Sackville Park, between the University of Manchester building on Whitworth Street and the Canal Street gay village. 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 memorial statue plaque in Sackville Park, Manchester

Turing is shown holding an apple—a symbol classically used to represent forbidden love, the object that inspired Isaac Newton'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: '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 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 computer, which was an early popular home computer, under the plinth, as a tribute to "the godfather of all modern computers".^[91]

In 1999, Time Magazine named Turing as one of the 100 Most Important People of the 20th century 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."^[2] Turing is featured in the 1999 Neal Stephenson novel "Cryptonomicon."

In 2002, Turing was ranked twenty-first on the BBC nationwide poll of the 100 Greatest Britons.^[92] In 2010, actor/playwright Jade Esteban Estrada portrayed Turing in the solo musical, "ICONS: The Lesbian and Gay History of the World, Vol. 4.". In 2011, in the Guardian's "My hero" series, writer Alan Garner chose Turing as his hero and described how they had met whilst out jogging in the early 1950s. Garner remembered Turing as "funny and witty" and said that he "talked endlessly". ^[93]

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, allowing them to stay at Bletchley Park.^[94]

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.^[95] Both the designer of the logo^[96] and the company deny that there is any homage to Turing in the design of the logo.^[97] In Series I, Episode 13 of the British television quiz show QI presenter Stephen Fry recounted a conversation had with Steve Jobs, saying that Jobs' response was, "It isn't true, but God, we wish it were."

Government apology[link]

In August 2009, John Graham-Cumming started a petition urging the British Government to posthumously apologise to Alan Turing for prosecuting him as a homosexual.^[98][99] The petition received thousands of signatures.^[100][101] Prime Minister Gordon Brown acknowledged the petition, releasing a statement on 10 September 2009 apologising and describing Turing's treatment as "appalling":^[6][100]

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.^[100][102]

In December 2011, William Jones created an e-petition^[103] requesting the British Government pardon Alan Turing for his conviction of "gross-indecency":^[104]

We ask the HM Government to grant a pardon to Alan Turing for the conviction of "gross indecency". In 1952, he was convicted of "gross indecency" with another man and was forced to undergo so-called "organo-therapy" - chemical castration. Two years later, he killed himself with cyanide, aged just 41. Alan Turing was driven to a terrible despair and early death by the nation he'd done so much to save. This remains a shame on the UK government and UK history. A pardon can go to some way to healing this damage. It may act as an apology to many of the other gay men, not as well known as Alan Turing, who were subjected to these laws.

The petition gained over 21,000 signatures, but the request was declined by Lord MacNally:^[105]

A posthumous pardon was not considered appropriate as Alan Turing was properly convicted of what at the time was a criminal offence. He would have known that his offence was against the law and that he would be prosecuted. It is tragic that Alan Turing was convicted of an offence which now seems both cruel and absurd—particularly poignant given his outstanding contribution to the war effort. However, the law at the time required a prosecution and, as such, long-standing policy has been to accept that such convictions took place and, rather than trying to alter the historical context and to put right what cannot be put right, ensure instead that we never again return to those times.

Tributes by universities[link]

The Alan Turing Building at the University of Manchester

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 on 5 June 2004.

• The Turing Room at the University of Edinburgh's School of Informatics houses a bust of Turing by Eduardo Paolozzi, and a set (#42/50) of his Turing prints (2000).
• The University of Surrey has a statue of Turing on their main piazza.
• Istanbul Bilgi University organises an annual conference on the theory of computation called "Turing Days".^[106]
• The University of Texas at Austin has an honours computer science programme named the Turing Scholars.^[107]
• The University of Puerto Rico in Humacao has a computer lab named after Turing.
• Keele University's School of Computing and Mathematics has a computing laboratory named after Turing.
• In the early 1960s Stanford University named the sole lecture room of the Polya Hall Mathematics building "Alan Turing Auditorium".^[108]
• One of the amphitheatres of the Computer Science department (LIFL^[109]) at the University of Lille in Northern France is named in honour of Alan M. Turing (the other amphitheatre is named after Kurt Gödel).
• The Department of Computer Science at Pontifical Catholic University of Chile, the Polytechnic University of Puerto Rico, Los Andes University in Bogotá, Colombia, King's College, Cambridge, Bangor University in Wales and Universities of Ghent and Mons in Belgium have computer laboratories named after Turing.
• The University of Manchester, the Open University, Oxford Brookes University and Aarhus University (in Århus, Denmark) all have buildings named after Turing.
• Alan Turing Road in the Surrey Research Park is named for Alan Turing.
• Carnegie Mellon University 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 Oregon has a bust of Turing on the side of the Deschutes Hall, the computer science building.^[110]
• The École Polytechnique Fédérale de Lausanne has a road and a square named after Alan Turing (Chemin de Alan Turing and Place de Alan Turing).^[111]

Centenary commemoration[link]

To mark the 100th anniversary of Turing's birth, the Turing Centenary Advisory Committee (TCAC) is coordinating the Alan Turing Year, a year-long programme of events around the world honouring Turing's life and achievements. The TCAC working with the University of Manchester faculty members and a broad spectrum of people from Cambridge University and Bletchley Park, is chaired by S. Barry Cooper, 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, New Zealand, Israel, Spain, Switzerland, Norway, Italy, Portugal 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 and the association Computability in Europe.^[112]

On February 23, 2012, the Royal Mail released a stamp featuring Turing as part its "Britons of Distinction" series.^[113]

The Turing Test, an opera by Julian Wagstaff which ran at the Edinburgh fringe in 2007, will also go on a UK tour in October to mark the 100th anniversary year of Turing's birth.^[114] The Turing Test is set in the near future and tells the fictional story of a brilliant young PhD student Stephanie, who is trapped in a bitter battle between two rival scientists racing to build the world's first truly intelligent computer.^[115]

See also[link]

	Biography portal
	Logic portal
	LGBT portal

• Good–Turing frequency estimation
• LU Decomposition
• Turing degree
• Turing completeness
• Turing machine
• Turing machine examples
• Turing pattern
• Turing reduction
• Turing switch
• Turing test
• Unorganized machine

Notes[link]