Alan Turing

British mathematician

• Born: June 23, 1912; London, England
• Died: June 7, 1954; Wilmslow, England

Twentieth-century British mathematician Alan Turing is regarded as one of the founders of modern computing. His research into machines and human thought helped shape the field of artificial intelligence.

Primary field: Mathematics

Specialties: Computability theory; logic; statistics

Early Life

Alan Mathison Turing was born in London, England, on June 23, 1912. As a student at the Sherborne School, he excelled at science and math, and he won a number of mathematics prizes despite his unconventional solutions. Turing went on to attend King’s College, Cambridge, where he continued to pursue mathematics at his own pace and using his own methods, with growing success. By 1933, Turing had begun to explore mathematical logic, which focuses on proofs and computation.

In 1936, Turing completed his first major paper, “On Computable Numbers, with an Application to the Entscheidungsproblem.” In the paper, published in the Proceedings of the London Mathematical Society, Turing describes a machine that could perform simple, carefully defined operations on paper tape. Turing modeled his machine on the action of a human following explicit instructions. This theoretical “Turing machine” was essentially a computer, although the technology did not yet exist to build the machine as described.

Also in 1936, Turing traveled to the United States and began his graduate studies at Princeton University. He earned his PhD from the university in 1938. He soon returned to Cambridge, where he began work on an analog mechanical device.

Life’s Work

World War II began soon after Turing’s return to England. The British Government Code and Cypher School (GCCS) asked Turing to use his mathematical skills to help decipher the codes being used by the Germans. German scientists had developed a device known as the Enigma cipher machine, which generated constantly changing codes that were nearly impossible to break. Turing helped design the Bombe, a machine that successfully deciphered the Enigma code, while working for the British government. Turing was also responsible for monitoring the communications of German submarines so that ships could be safely rerouted to avoid them.

Building on Turing’s work, other members of the GCCS designed Colossus, the first electronic, programmable, and digital computer. Unlike later computers, Colossus required that those operating it change some of the machine’s wiring manually to set it up for a new job. Although its functions were limited, Colossus proved that digital electronic computing machinery was feasible. For his part in the war effort, Turing was granted the title of Officer of the Order of the British Empire.

After the war, Turing went to work for Britain’s National Physical Laboratory (NPL), where he designed a computer that was based on programs rather than on the rearrangement of electronic parts. Turing’s proposed computer could handle many different types of tasks ranging from numerical work to algebra, file management, and code breaking. However, this computer was never built.

In 1947, Turing left the NPL for the University of Manchester, where he worked on the development of the Manchester Automatic Digital Machine, another early computer. In 1950, he published his paper “Computing Machinery and Intelligence,” introducing the concept of artificial intelligence. Turing believed that it was possible to create a machine that would imitate the processes of the human brain. Turing also proposed the “Turing test,” which could be used to explore the question of whether a computer can think for itself.

The Turing test challenges a machine’s capability to perform humanlike conversation. During the test, a human judge conducts a conversation with a human and a machine. If the judge cannot tell which is which, then the machine passes the test. Turing originally proposed the test to address objectively the question of whether machines can think. Turing believed that if the judge cannot tell the machine from the human after a reasonable amount of time, the machine is somewhat intelligent.

During the final years of his life, Turing worked on the concept that later came to be called artificial life. Turing’s main focus in biology was the physical structure of living things. He was interested in how and why organisms develop particular shapes, and he wondered how simple cells know how to grow into complex forms. Turing saw the development of natural forms such as plants and animals as nothing more than a simple set of steps, or an algorithm. He used a computer to simulate a chemical mechanism that the genes of a zygote, or egg, use to determine the anatomical structure of an animal or plant. At the same time, he was experimenting with neural networks and brain structure. Turing’s ultimate goal was to merge already established biological theory with mathematics and computers.

Turing was elected a fellow of the Royal Society of London in 1951, primarily in recognition of his work on Turing machines in the 1930s. In 1952, he published a theoretical paper on morphogenesis, the formation of living organisms. He also researched such topics as quantum theory and relativity theory.

In 1952, Turing was arrested and tried for engaging in a homosexual relationship, which was considered a crime in Britain. To avoid prison, he agreed to receive estrogen injections for one year in order to “neutralize” his homosexuality. Additionally, he was perceived as a security risk and subsequently lost his security clearance and ability to work for the government. Turing died on June 7, 1954. At the time, it was ruled a suicide.

Impact

Turing made many contributions to mathematics, logic, and statistics. He is best remembered, however, for his contributions to computability, machine design, and artificial intelligence. His work on computability, especially the universal Turing machine concept, was the first modern work on the theory of computation and became a central idea in recursive function theory (an active area of research in mathematical logic) and in automata theory (an important theoretical discipline within computer science). The value of Turing’s efforts in the design of code-breaking equipment to the war effort was also significant. His work at the NPL resulted in the creation of one of the first operating modern computers, which was used for important scientific and engineering applications in the 1950s. Turing’s work also influenced the design of later computers, though his design ideas largely fell outside the mainstream of computer design developments.

Turing was especially influential as the foremost champion of artificial intelligence research in the first decade of modern computing. He introduced the distinction between robotics and artificial intelligence research, arguing that the future of artificial intelligence lay in the use of the stored-program computer, not in the construction of special-purpose robots that could mimic vision or other human attributes. The Turing test has endured as the principal test of success in artificial intelligence research. In the decades since Turing’s death, the field of artificial intelligence has advanced to the point at which computers can be programmed to read stories and answer questions about them, assist medical doctors in diagnoses, play chess at the expert level, and assist humans in numerous information-processing tasks that have become commonplace in society.

Bibliography

Copeland, B. Jack, ed. Alan Turing’s Automatic Computing Engine: The Master Codebreaker’s Struggle to Build the Modern Computer. New York: Oxford UP, 2005. Print. Provides a detailed history of Turing’s contributions to computer science and presents diagrams and illustrations explaining the hardware, software, and other features of Turing’s computers.

Graham-Cumming, John. “Alan Turing: Computation.” New Scientist 214.2867 (2012): 2. Print. Describes Turing’s scientific achievements and discusses his efforts as a code breaker during World War II and his foundational work in computer science.

Hodges, Andrew. Alan Turing: The Enigma—The Centenary Edition. Princeton: Princeton UP, 2012. Print. Offers a biography of Turing, covering his influence on modern computer sciences, artificial intelligence, and the gay rights movement.

Petzold, Charles. The Annotated Turing: A Guided Tour through Alan Turing’s Historic Paper on Computability and the Turing Machine. Hoboken: Wiley, 2008. Print. Guides readers through Turing’s landmark paper, offering detailed explanation and examples.

Turing, Alan. “Computing Machinery and Intelligence.” Mind 59 (1950): 433–60. Print. Provides Turing’s counterarguments to common objections against artificial intelligence and introduces the Turing test, which decides when a computer has achieved intelligence.