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Alan Turing: A Brief Biography

No one person invented the computer, but the most important figure in the development of computer science in the twentieth century was doubtless Alan Matheson Turing. Turing was born in 1912 in London. His father served in India, which at the time was a British colony. Alan, along with his brother, John, was raised in English foster homes, far from his parents, and attended the Sherbourne public school, where he was a mediocre student, at best. The school reports of this budding genius tell of a boy whose handwriting was terrible, who failed Latin and history, and who, most shocking of all at the time, had no proper grounding in religion. 

At Sherbourne, Turing became fast friends with Christopher Morcom, with whom he shared a growing interest, unrecognized by his rigid teachers, in mathematics and astronomy. Morcomís early death, in 1930, devastated the young Turing, whose life had already been more than commonly devoid of warmth and companionship. Morcomís death led Turing to speculate about the possibility of survival after death and to wonder whether belief in such survival was consistent with modern science, especially with the exciting discoveries of the new physicsórelativity theory and quantum mechanics. 

From 1931 to 1934, Turing studied at Kingís College, Cambridge, and in 1935 he was elected a fellow of the college. After receiving the M.A. degree from Kingís College and a Smithís prize for work in probability theory, Turing published ìOn Computable Numbers,î a paper that simultaneously explained what problems in mathematics were computable and described a simple mechanism, logically analogous to modern computers, capable of carrying out those computations. This so-called ìTuring Machineî provides the theoretical basis for modern computer science. In effect, Turing created on paper the concept of the modern computer, the encoding of both instructions and data in a universal form, long before computers were actually built. 

After a stint at Princeton, in the United States, where he received a Ph.D. in mathematical logic, Turing returned to England and to his fellowship at Kingís College. The British government soon drafted him to assist its effort to defeat Nazi Germany. The Nazis were using a machine called the Enigma to encrypt secret wartime communications. Turing headed a team of mathematicians who built a device called the Bombe that could decipher messages encrypted by the Enigma machine, thus giving the Allies access to critical battle plans and strategies. By breaking the Enigma code, Turing helped make it possible for the United States to seize control of the Atlantic from German U-2 boats, which in turn made possible the Allied invasion of Europe. 

When the war was over, Turing turned his attention to designing a real electronic computer to embody his concept of a universal computing machine, the Automated Computing Engine, or ACE. In those times, most people thought of computers as machines for doing calculations, but Turing had grander plans. Based on his belief that there is no substantive difference between a computer and a human brain, both of which are calculating machines, Turing imagined a machine equally at home doing mathematics, breaking codes, or playing chess. His work on Abbreviated Code Instructions for the Automated Computing Engine was one of the earliest developments of a programming language. He also experimented with creating computer systems that could learn, thus presaging modern neural nets. During this time, Turing, who had long enjoyed long-distance running, became an accomplished competitor in cross-country races. According to his biographer Andrew Hodges, he would have been ìseriously consideredî for a spot on the British team in the 1948 Olympics were it not for an untimely injury. 

In 1950, Turing published in the journal Mind a now-famous paper entitled ìComputing Machinery and Intelligence.î In this paper, Turing proposed an experiment, commonly known as The Turing Test, to settle the question of whether a computer can be considered intelligent. In this experiment, a person placed in one room communicates with a computer located in another room. Turing argued that if the person communicating with the computer believes that he or she is actually communicating with a human being, then the computer would have to be considered intelligent. In 1990, Dr. Hugh Loebner established the Loebner prize, offering $100,000 to anyone who could write a program that could successfully pass The Turing Test. Since then, the annual Loebner prize contest has stimulated the creation of many fascinating programs that mimic human conversation, but no one has yet claimed the $100,000 grand prize. 

By any standard, Alan Turing was one of the most gifted persons in the history of science or of mathematics. He laid the theoretical groundwork for computing and helped the Allies win World War II by breaking the Enigma code. He also made fundamental contributions to pure mathematics and to the development of programming languages, neural nets, and artificial intelligence. In the last years of his life, he turned his attention to the mathematical study of morphogenesis, the science of the development of biological forms. 

Sadly, this brilliant manís career was cut short.  In 1952, his home was burglarized by the friend of a male lover. Turing reported the burglary to the police but then was himself arrested because of his sexual orientation. Turing was tried for sodomy and publicly humiliated. Because of his homosexuality, his security clearance was revoked, and he was forced to undergo chemical castration by means of injections of the female hormone estrogen. The man who had invented modern computing and saved his country in wartime was found dead in 1954, an apparent suicide by means of cyanide poisoning. 

The story of the tragic end of Turingís life is told in Hugh Whitemoreís play Breaking the Code, a film version of which, starring Derek Jacobi and Harold Pinter, aired on United States television in February, 1997. There is also an excellent biography of Turing, Alan Turing: The Enigma, by Andrew Hodges. 

Questions for Discussion and Review 

The following questions are based on the preceding text. Clicking on a question will take you to the place in the text where the question is discussed. To return to these questions, simply click the "Back" button in your browser. 

1. What fundamental contribution did Turing make to the theory of computing in his paper "On Computable Numbers"? 

2. How did Turing help the Allies to win World War II? 

3. What contributions did Turing make to the development of software for computers? 

4. What is The Turing Test? Do you believe that a computer will ever be able to pass such as test? Why, or why not? 

5. How did Turing's life end? Why did it end this way? How would his later life have been different if the mores of today prevailed during the 1950s? 

World Wide Web Links to Sites Related to the Article 

The Alan Turing Home Page, by Turing's Biographer, Andrew Hodges 

Turing Machines 1 
Turing Machines 2 
Turing Machines 3


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