Alan Turing was one of the leading theoreticians of digital computer scienceduring the 1930s, 1940s, and 1950s. Throughout his life, he used mathematicsas a way to explore whether nature, including human thought, worked like a machine. He is generally considered to be the founder of the field of artificial intelligence.
Turing was born in London, England. His father was a colonial civil servant and his mother came from a family of scholarly men and women. Turing receivedhis undergraduate degree in mathematics at Cambridge University in 1935. He spent the next three years doing graduate work at Princeton University, wherehe worked with the logician Alonzo Church.
While at Princeton, Turing defined a theoretical machine that used a binary code to solve mathematical problems or carry out a series of instructions onestep at a time. The machine could work with only a specified number of conditions, and it used a tape divided into squares, each of which carried a symbol. The machine scanned one square at a time, remembering all the symbols. Themachine's behavior at any one time depended on the number of conditions and the number of remembered symbols. It could change its behavior by changing either the number of conditions or by shifting from one square to another. Furthermore, the machine could be employed for a special purpose or for universaluse on any special problem, as long as the tape carried the necessary instructions.
Turing also proved logically that some problems could not be solved by such amachine. He soon learned that several other theorists had devised their ownsystems to produce an equally strong proof. One was Church's lambda (&lgr;) calculus, which is now used in artificial intelligence programming. The Turingmachine became a starting point for modern automata theory, a formal mathematical study of computers and other logical machines.
During World War II, Turing helped design computer-like devices, such as theColossus series, that broke German military codes produced with its Enigma cipher machines. While the war was in progress, Turing again spent some time inthe United States, possibly conferring with the mathematician John Von Neumann of the Institute for Advanced Studies in Princeton, New Jersey, who was working on computer designs.
After 1945, when the war ended, Turing designed the Automatic Computing Engine (ACE) at Britain's National Physical Laboratory. However, the existing technology was not adequate and computer construction was very slow.
Frustrated, he joined the faculty at Manchester University in 1948, where heturned his efforts to the nature of intelligence and information. Like the American Norbert Wiener (1894-1964), the founder of cybernetics, Turing believed that intelligence was strictly a matter of processing information, and thathuman thought and the operations of an intelligent machine differed only bydegree. He was convinced that just as artificial sensors performed the same operations as human ones, such as cameras and eyes, computers could perform the functions of the human brain.
In 1950, Turing invented a test for an intelligent machine: If a knowledgeable person cannot tell whether a problem is being solved by a computer or a person, the computer that solved the problem is "intelligent." Today some peopleare still trying to design computers and programs that can pass Turing's test. However, not all students of artificial intelligence support Turing's definition. Some believe that human thought involves more than computation alone.
Turing also investigated the mathematical aspects of biological interactions.He was named a Fellow of the Royal Society in 1951. He died in 1954, probably by suicide and possibly because of concerns that his homosexuality would become publicly known.