A difference engine: computing the solution to a polynomial function

Computer laboratory, Moody Hall, James Madison University, 2003

Wikimedia servers

Computing is the activity of using computer hardware and software.

Definitions[link]

Computing Curricula 2005^[1] defined "computing" as:

"In a general way, we can define computing to mean any goal-oriented activity requiring, benefiting from, or creating computers. Thus, computing includes designing and building hardware and software systems for a wide range of purposes; processing, structuring, and managing various kinds of information; doing scientific studies using computers; making computer systems behave intelligently; creating and using communications and entertainment media; finding and gathering information relevant to any particular purpose, and so on. The list is virtually endless, and the possibilities are vast."

The term "computing" has sometimes been narrowly defined, as in a 1989 ACM report on Computing as a Discipline^[2]:

The discipline of computing is the systematic study of algorithmic processes that describe and transform information: their theory, analysis, design, efficiency, implementation, and application. The fundamental question underlying all computing is "What can be (efficiently) automated?"

Computing Curricula 2005^[1] also recognizes that the meaning of "computing" depends on the context:

Computing also has other meanings that are more specific, based on the context in which the term is used. For example, an information systems specialist will view computing somewhat differently from a software engineer. Regardless of the context, doing computing well can be complicated and difficult. Because society needs people to do computing well, we must think of computing not only as a profession but also as a discipline.

The term "computing" is also synonymous with counting and calculating. In earlier times, it was used in reference to mechanical computing machines.

A computer is a machine that reads, stores, manipulates and displays data. The most common example are the various personal computers. Other common examples include: mobile phones, mp3 players, or video game consoles.

Computer[link]

A computer is a machine that manipulates data according to a set of instructions called a computer program. The program has an executable form that the computer can use directly to execute the instructions. The same program in its human-readable source code form, enables a programmer to study and develop the algorithm. Because the instructions can be carried out in different types of computers, a single set of source instructions converts to machine instructions according to the central processing unit type.

The execution process carries out the instructions in a computer program. Instructions express the computations performed by the computer. They trigger sequences of simple actions on the executing machine. Those actions produce effects according to the semantics of the instructions.

Computer software[link]

Computer software or just "software", is a collection of computer programs and related data that provides the instructions for telling a computer what to do and how to do it. Software refers to one or more computer programs and data held in the storage of the computer for some purposes. In other words, software is a set of programs, procedures, algorithms and its documentation concerned with the operation of a data processing system. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. The term was coined to contrast to the old term hardware (meaning physical devices). In contrast to hardware, software "cannot be touched".^[3] Software is also sometimes used in a more narrow sense, meaning application software only. Sometimes the term includes data that has not traditionally been associated with computers, such as film, tapes, and records.^[4]

Application software[link]

Application software, also known as an "application" or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with documents. Apps may be bundled with the computer and its system software, or may be published separately. Some users are satisfied with the bundled apps and need never install one.

Application software is contrasted with system software and middleware, which manage and integrate a computer's capabilities, but typically do not directly apply them in the performance of tasks that benefit the user. The system software serves the application, which in turn serves the user.

Similar relationships apply in other fields. For example, a shopping mall does not provide the merchandise a shopper is seeking, but provides space and services for retailers that serve the shopper. A bridge may similarly support rail tracks which support trains, allowing the trains to transport passengers.

Application software applies the power of a particular computing platform or system software to a particular purpose. Some apps such as Microsoft Office are available in versions for several different platforms; others have narrower requirements and are thus called, for example, a Geography application for Windows or an Android application for education or Linux gaming. Sometimes a new and popular application arises which only runs on one platform, increasing the desirability of that platform. This is called a killer application.

Computer user[link]

A user is an agent, either a human agent (end-user) or software agent, who uses a computer or network service. A user often has a user account and is identified by a username (also user name), screen name (also screenname), nickname (also nick), or handle, which is derived from the identical Citizen's Band radio term.

Users are also widely characterized as the class of people that use a system without complete technical expertise required to understand the system fully.[1] In hacker-related contexts, such users are also divided into lusers and power users.

In projects in which the actor of the system is another system or a software agent, it is quite possible that there is no end-user for the system. In this case, the end-users for the system would be indirect end-users.

Enthusiast computing[link]

Enthusiast computing refers to a sub-culture of personal computer users who focus on extremely high-performance computers. Manufacturers of performance-oriented parts typically include an enthusiast model in their offerings. Enthusiast computers (often referred to as a "box", "build", or "rig" by their owners) commonly feature extravagant cases and high-end components, and are sometimes liquid cooled.

Although high-end computers may be bought retail in the same manner as the common computer, they are frequently built by their owners. Enthusiasts build their systems in order to produce a computer that will out-perform an opponent's computer, thereby "winning" in a contest; to simply enjoy the best images and effects a new PC game has to offer; or even simply to obtain the best possible performance at a variety of tasks.

Computer programming[link]

Computer programming in general is the process of writing, testing, debugging, and maintaining the source code and documentation of computer programs. This source code is written in a programming language, which is an artificial language often more restrictive or demanding than natural languages, but easily translated by the computer. The purpose of programming is to invoke the desired behaviour (customization) from the machine. The process of writing high quality source code requires knowledge of both the application's domain and the computer science domain. The highest-quality software is thus developed by a team of various domain experts, each person a specialist in some area of development. But the term programmer may apply to a range of program quality, from hacker to open source contributor to professional. And a single programmer could do most or all of the computer programming needed to generate the proof of concept to launch a new "killer" application.

Computer programmer[link]

A programmer, computer programmer, or coder is a person who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst. A programmer's primary computer language (C, C++, Java, Lisp, Python etc.) is often prefixed to the above titles, and those who work in a web environment often prefix their titles with web. The term programmer can be used to refer to a software developer, software engineer, computer scientist, or software analyst. However, members of these professions typically^{[citation needed]} possess other software engineering skills, beyond programming; for this reason, the term programmer is sometimes considered an insulting or derogatory oversimplification of these other professions^{[citation needed]}. This has sparked much debate amongst developers, analysts, computer scientists, programmers, and outsiders who continue to be puzzled at the subtle differences in the definitions of these occupations.^{[5][6][7][8][9]}

Computer science[link]

Computer science or computing science (abbreviated CS or compsci) is the scientific and mathematical approach in information technology and computing.^[10][11] A computer scientist is a person who does work at a professional level in computer science and/or has attained a degree in computer science or a related field.

Its subfields can be divided into practical techniques for its implementation and application in computer systems and purely theoretical areas. Some, such as computational complexity theory, which studies fundamental properties of computational problems, are highly abstract, while others, such as computer graphics, emphasize real-world applications. Still others focus on the challenges in implementing computations. For example, programming language theory studies approaches to description of computations, while the study of computer programming itself investigates various aspects of the use of programming languages and complex systems, and human-computer interaction focuses on the challenges in making computers and computations useful, usable, and universally accessible to humans.

History of computing[link]

The history of computing is longer than the history of computing hardware and modern computing technology and includes the history of methods intended for pen and paper or for chalk and slate, with or without the aid of tables.

Computing is intimately tied to the representation of numbers. But long before abstractions like the number arose, there were mathematical concepts to serve the purposes of civilization. These concepts include one-to-one correspondence (the basis of counting), comparison to a standard (used for measurement), and the 3-4-5 right triangle (a device for assuring a right angle).

Eventually, the concept of numbers became concrete and familiar enough for counting to arise, at times with sing-song mnemonics to teach sequences to others. All the known languages have words for at least "one" and "two" (although this is disputed: see Piraha language), and even some animals like the blackbird can distinguish a surprising number of items.^[12]

The earliest known tool for use in computation was the abacus, and it was thought to have been invented in Babylon circa 2400 BC. Its original style of usage was by lines drawn in sand with pebbles. Abaci, of a more modern design, are still used as calculation tools today. This was the first known computer and most advanced system of calculation known to date - preceding Greek methods by 2,000 years.

Computer network[link]

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information.^[13] Where at least one process in one device is able to send/receive data to/from at least one process residing in a remote device, then the two devices are said to be in a network.

Networks may be classified according to a wide variety of characteristics such as the medium used to transport the data, communications protocol used, scale, topology, and organizational scope.

Communications protocols define the rules and data formats for exchanging information in a computer network, and provide the basis for network programming. Well-known communications protocols are Ethernet, a hardware and Link Layer standard that is ubiquitous in local area networks, and the Internet Protocol Suite, which defines a set of protocols for internetworking, i.e. for data communication between multiple networks, as well as host-to-host data transfer, and application-specific data transmission formats.

Computer networking is sometimes considered a sub-discipline of electrical engineering, telecommunications, computer science, information technology or computer engineering, since it relies upon the theoretical and practical application of these disciplines.

Internet[link]

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support email.

Computer industry[link]

The computer industry is made up of all of the businesses involved in developing computer software, designing computer hardware and computer networking infrastructures, the manufacture of computer components and the provision of information technology services.

Software industry[link]

The software industry includes businesses for development, maintenance and publication of software that are using any business model. The industry also includes software services, such as training, documentation, and consulting.

See also[link]

	Information technology portal
	Computer Science portal
	Computing portal

Wikiversity has learning materials about computing

• Index of history of computing articles
• List of computer term etymologies

References[link]

External links[link]

Wikibooks has more on the topic of Computing

Look up computing in Wiktionary, the free dictionary.

• http://foldoc.org/contents.html Free on-line dictionary of computing
• http://pubs.doc.ic.ac.uk/ open-access repository of publications - Department of Computing - Imperial College London

This article contains Japanese text. Without proper rendering support, you may see question marks, boxes, or other symbols instead of kanji and kana.

Michio Kaku (加来 道雄, Kaku Michio^?, born January 24, 1947) is an American theoretical physicist, the Henry Semat Professor of Theoretical Physics in the City College of New York of City University of New York, a co-founder of string field theory,^[1] a futurist, and a "communicator" and "popularizer" of science. He has written several books about physics and related topics; he has made frequent appearances on radio, television, and film; and he writes extensive online blogs and articles. He has written two New York Times best sellers, Physics of the Impossible (2008) and Physics of the Future (2011). He has hosted several TV specials for BBC-TV, the Discovery Channel, and the Science Channel.

Early life and education[link]

Kaku was born in San Jose, California to Japanese immigrant parents. His grandfather came to the United States to take part in the clean-up operation after the 1906 San Francisco Earthquake^{[citation needed]}. His father was born in California but was educated in Japan and spoke little English. Both his parents were put in the Tule Lake War Relocation Center, where they met and where his two brothers were born.

At Cubberley High School in Palo Alto, Kaku assembled an atom smasher in his parents' garage for a science fair project.^[2] At the National Science Fair in Albuquerque, New Mexico, he attracted the attention of physicist Edward Teller, who took Kaku as a protégé, awarding him the Hertz Engineering Scholarship. Kaku graduated summa cum laude from Harvard University in 1968 and was first in his physics class. He attended the Berkeley Radiation Laboratory at the University of California, Berkeley and received a Ph.D. in 1972, and in 1972 he held a lectureship at Princeton University.

During the Vietnam War, Kaku completed his U.S. Army basic training at Fort Benning, Georgia and his advanced individual training at Fort Lewis, Washington.^[3] However, the Vietnam War ended before he was deployed as an infantryman.

Academic career[link]

Kaku became a visiting professor at the Institute for Advanced Study in Princeton,^[4] and New York University.^[5] He currently holds the Henry Semat Chair and Professorship in theoretical physics at the City College of New York.^[6]

Kaku has had over 70 articles published in physics journals such as Physical Review, covering topics such as superstring theory, supergravity, supersymmetry, and hadronic physics.^[7] In 1974, along with Prof. Keiji Kikkawa of Osaka University, he authored the first papers describing string theory in a field form.^[8][9]

Kaku is the author of several textbooks on string theory and quantum field theory.

Popular science[link]

Kaku is most widely known as a popularizer of science.^[10] He has written books and appeared on many television programs as well as film. He also hosts a weekly radio program.

Books[link]

Kaku is the author of various popular science books.

• Hyperspace (1994)
• Beyond Einstein (with Jennifer Thompson) (1995)
• Visions: How Science Will Revolutionize the 21st Century^[11] (1998)
• Einstein's Cosmos (2004)
• Parallel Worlds (2004)
• Physics of the Impossible (2008)
• Physics of the Future (2011)

Hyperspace was a best-seller and was voted one of the best science books of the year by both The New York Times^[10] and The Washington Post. Parallel Worlds was a finalist for the Samuel Johnson Prize for non-fiction in the UK.^[12]

Radio[link]

Kaku is the host of the weekly, one-hour radio program Explorations, produced by the Pacifica Foundation's WBAI in New York. "Explorations" is syndicated to community and independent radio stations and makes previous broadcasts available on the program's website. Kaku defines the show as dealing with the general topics of science, war, peace, and the environment.

In April 2006, Kaku began broadcasting Science Fantastic on 90 commercial radio stations, the only nationally syndicated science program on commercial radio in the United States. It is syndicated by Talk Radio Network and now reaches 130 radio stations and America's Talk on XM. The program is formatted as a live listener call-in show, focusing on "futurology," which he defines as the future of science.^{[citation needed]} Featured guests include Nobel laureates and top researchers on the topics of string theory, time travel, black holes, gene therapy, aging, space travel, artificial intelligence, and SETI. When Kaku is busy filming for television, Science Fantastic goes on hiatus, sometimes for several months. Kaku is also a frequent guest on many programs, where he is outspoken in all areas and issues he considers of importance, such as the program Coast to Coast AM, where on 30 November 2007, he reaffirmed his belief that there is a 100% probability of extraterrestrial life in the universe.^[13]

Kaku has appeared on The Opie and Anthony Show a number of times, discussing popular fiction such as Back to The Future, Lost, and the theories behind time-travel that these and other fictional entertainment focus on.

Television and film[link]

Kaku has appeared in many forms of media and on many programs and networks, including Good Morning America, The Screen Savers, Larry King Live, 60 Minutes, Nightline, 20/20, Naked Science, CNN, ABC News, CBS News, NBC News, Al Jazeera English, Fox News Channel, The History Channel, Conan, The Science Channel, The Discovery Channel, TLC, Countdown with Keith Olbermann, The Colbert Report, The Art Bell Show and its successor, Coast To Coast AM, BBC World News America, The Opie & Anthony Show, The Covino & Rich Show, Head Rush, The Late Show with David Letterman, and Real Time with Bill Maher.

In 1999, Kaku was one of the scientists profiled in the feature-length film Me and Isaac Newton, directed by Michael Apted. It played theatrically in the United States, was later broadcast on national TV, and won several film awards.^{[citation needed]}

In 2005, Kaku appeared in the short documentary Obsessed & Scientific. The film is about the possibility of time travel and the people who dream about it. It screened at the Montreal World Film Festival and a feature film expansion is in development talks. Kaku also appeared in the ABC documentary UFOs: Seeing Is Believing, in which he suggested that while he believes it is extremely unlikely that extraterrestrials have ever actually visited Earth, we must keep our minds open to the possible existence of civilizations a million years ahead of us in technology, where entirely new avenues of physics open up. He also discussed the future of interstellar exploration and alien life in the Discovery Channel special Alien Planet as one of the multiple speakers who co-hosted the show, and Einstein's Theory of Relativity on The History Channel.

In February 2006, Kaku appeared as presenter in the BBC-TV four-part documentary Time which seeks to explore the mysterious nature of time. Part one of the series concerns personal time, and how we perceive and measure the passing of time. The second in the series deals with cheating time, exploring possibilities of extending the lifespan of organisms. The geological time covered in part three explores the ages of the earth and the sun. Part four covers the topics of cosmological time, the beginning of time and the events that occurred at the instant of the big bang.

On January 28, 2007, Kaku hosted the Discovery Channel series 2057. This three-hour program discussed how medicine, the city, and energy could change over the next 50 years.

In 2008, Kaku hosted the three-hour BBC-TV documentary Visions of the Future, on the future of computers, medicine, and quantum physics, and he appeared in several episodes of the History Channel's Universe series.

On December 1, 2009, he began hosting a 12-episode weekly TV series for the Science Channel at 10 pm, called Sci Fi Science: Physics of the Impossible, based on his best-selling book. Each 30-minute episode discusses the scientific basis behind imaginative schemes, such as time travel, parallel universes, warp drive, star ships, light sabers, force fields, teleportation, invisibility, death stars, and even superpowers and flying saucers. Each episode includes interviews with the world's top scientists working on prototypes of these technologies, interviews with science fiction fans, clips from science fiction movies, and special effects and computer graphics. Although these inventions are impossible today, the series discusses when these technologies might become feasible in the future.^[14]

In 2010, he began to appear in a series on the website Gametrailers.com called Science of Games, discussing the scientific aspects of various popular video games such as Mass Effect 2 and Star Wars: The Force Unleashed.

Kaku is popular in mainstream media because of his knowledge and his accessible approach to presenting complex subjects in science. While his technical writings are confined to theoretical physics, his public speaking and media appearances cover a broad range of topics, from the Kardashev scale to more esoteric subjects such as wormholes and time travel. In January 2007, Kaku visited Oman. While there, he talked at length to select members of that country's decision makers. In an interview with local media, Dr Kaku elaborated on his vision of mankind's future. Kaku considers climate change and terrorism as serious threats in man's evolution from a Type 0 civilization to Type 1.^[15]

He is pictured in Symphony of Science's newest song (as of September 6, 2011), 'The Quantum World.'

On October 11, 2010, Michio Kaku appeared in the BBC program "What Happened Before the Big Bang" (along with Laura Mersini-Houghton, Andrei Linde, Roger Penrose, Lee Smolin, Neil Turok, and other notable cosmologists and physicists), where he propounded his theory of the universe created out of nothing.^[16]

Social policy advocacy[link]

Kaku has publicly stated his concerns over matters including the anthropogenic cause of global warming, nuclear armament, nuclear power and the general misuse of science.^[17] He was critical of the Cassini–Huygens space probe because of the 72 pounds (33 kg) of plutonium contained in the craft for use by its radioisotope thermoelectric generator. Conscious of the possibility of casualties if the probe's fuel were dispersed into the environment during a malfunction and crash as the probe was making a 'sling-shot' maneuver around earth, Kaku publicly criticized NASA's risk assessment.^[18] He has also spoken on the dangers of space junk and called for more and better monitoring. Kaku is generally a vigorous supporter of the exploration of outer space, believing that the ultimate destiny of the human race may lie in extrasolar planets; but he is critical of some of the cost-ineffective missions and methods of NASA.

Kaku credits his anti-nuclear war position to programs he heard on the Pacifica Radio network, during his student years in California. It was during this period that he made the decision to turn away from a career developing the next generation of nuclear weapons in association with Edward Teller and focused on research, teaching, writing and media.^{[citation needed]} Kaku joined with others such as Helen Caldicott, Jonathan Schell, Peace Action and was instrumental in building a global anti-nuclear weapons movement that arose in the 1980s, during the administration of U.S. President Ronald Reagan.

Kaku was a board member of Peace Action and on the board of radio station WBAI-FM in New York City where he originated his long running program, Explorations, that focused on the issues of science, war, peace and the environment.

His remark from an interview in support of SETI, "We could be in the middle of an intergalactic conversation...and we wouldn't even know.", is used in the third Symphony of Science installment "Our Place in the Cosmos".

Personal life[link]

Kaku is married to Shizue Kaku and has two daughters.^[19]

Bibliography[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Michio Kaku

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• Official website
• Michio Kaku on Twitter
• Getting Physical: Dr. Michio Kaku Explains Einstein's Genius
• Russia Takes Aim at Asteroids, op-ed on asteroid defense, Wall St. Journal, Jan. 5, 2010
• The Skeptics' Guide To The Universe interview
• Michio Kaku at the Internet Movie Database
• Michio Kaku on National Public Radio
• About Michio Kaku
• Video: Michio Kaku discusses Physics of the Future on March 23, 2011, on Forum Network.
• In Depth interview with Kaku, October 3, 2010

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]

References[link]

Further reading[link]

• Alan Turing at the Mathematics Genealogy Project
• Jack Copeland, ed. "The Mind and the Computing Machine: Alan Turing and others". The Rutherford Journal. http://www.rutherfordjournal.org/article010111.html. 
• Hodges, Andrew (27 August 2007). "Alan Turing". In Edward N. Zalta. Stanford Encyclopedia of Philosophy (Winter 2009 ed.). Stanford University. http://plato.stanford.edu/entries/turing/. Retrieved 10 January 2011. 
• Gray, Paul (29 March 1999). "Computer Scientist: Alan Turing". TIME. http://www.time.com/time/magazine/article/0,9171,990624,00.html. 
• Gleick, James, The Information: A History, A Theory, A Flood, New York: Pantheon, 2011, ISBN 978-0-375-42372-7
• Leavitt, David, The Man Who Knew Too Much: Alan Turing and the Invention of the Computer, W. W. Norton, 2006

External links[link]

Wikiquote has a collection of quotations related to: Alan Turing

Wikimedia Commons has media related to: Alan Turing

• Alan Turing RKBExplorer
• Alan Turing Year
• CiE 2012: Turing Centenary Conference
• Visual Turing
• Turing Machine calculators at Wolfram Alpha
• Alan Turing site maintained by Andrew Hodges including a short biography
• AlanTuring.net – Turing Archive for the History of Computing by Jack Copeland
• The Turing Archive – contains scans of some unpublished documents and material from the Kings College, Cambridge archive
• Jones, G. James (11 December 2001). "Alan Turing – Towards a Digital Mind: Part 1". System Toolbox (The Binary Freedom Project). http://www.systemtoolbox.com/article.php?history_id=3. 
• Sherborne School Archives – holds papers relating to Alan Turing's time at Sherborne School
• Alan Turing plaques recorded on openplaques.org

Papers[link]

• An extensive list of Turing's papers, reports and lectures, plus translated versions and collections BibNetWiki
• List of publications from Microsoft Academic Search.
• Turing, Alan (October 1950), "Computing Machinery and Intelligence", Mind LIX (236): 433–460, DOI:10.1093/mind/LIX.236.433, ISSN 0026-4423, http://loebner.net/Prizef/TuringArticle.html, retrieved 2008-08-18 
• Oral history interview with Nicholas C. Metropolis, Charles Babbage Institute, University of Minnesota. Metropolis was the first director of computing services at Los Alamos National Laboratory; topics include the relationship between Alan Turing and John von Neumann