The life of Alan Turing

Timeline

1. 1912
   Born on 23 June in London. His parents live in India.
2. 1926
   Starts at Sherborne boarding school.
3. 1930
   Christopher Morcom, his best friend, dies.
4. 1931
   Enters King’s College, Cambridge.
5. 1935
   Elected a fellow of King’s, aged 22.
6. 1936
   Writes “On computable numbers”. Goes to Princeton.
7. 1938
   Doctorate at Princeton. Returns to Cambridge.
8. 1939
   Starts work at Bletchley Park, on breaking the Enigma.
9. 1940
   The first electromechanical bombe comes into operation.
10. 1945
    Moves to the National Physical Laboratory, where he designs the ACE.
11. 1948
    Moves to the University of Manchester.
12. 1950
    Publishes the paper on the imitation game.
13. 1952
    Publishes the theory of morphogenesis. Convicted for homosexuality.
14. 1954
    Dies on 7 June, in Wilmslow, aged 41.

A boy raised far from his parents

Alan Mathison Turing was born on 23 June 1912, in London. His father, Julius, was a British civil servant in India, and his mother, Ethel Sara, went back there soon after the birth. Alan and his elder brother, John, were brought up by a retired army couple in the south of England and saw their parents only when they were on leave.

He was a clumsy boy with dreadful handwriting who was interested in everything natural: plants, chemistry, maps, numbers. He taught himself to read in three weeks and did experiments with whatever he found at home.

Sherborne and Christopher

In May 1926, aged 13, Turing was due to start at Sherborne boarding school, in the south-west of England. It was the day of the General Strike, and there were no trains. He cycled from Southampton to the school, about a hundred kilometres, and spent the night at an inn halfway. A local newspaper reported the journey.

The school wanted to turn out gentlemen versed in Latin and Greek, and the headmaster complained that the boy “is wasting his time” on science. Turing read Einstein on his own and solved advanced problems without having studied calculus.

At Sherborne he met Christopher Morcom, a year older and also passionate about science. Christopher was his first great friend and, by all accounts, his first love. In February 1930 he died of bovine tuberculosis within a few days. Turing was devastated and spent years wondering whether a person’s mind survives the body and how mind is linked to matter. It is the question that, twenty years later, reappears in the imitation game.

Cambridge and the 1936 paper

In 1931 he entered King’s College, Cambridge, to study mathematics. He rowed, ran long distances and graduated with distinction. In 1935, aged 22, he was elected a fellow of the college for a proof of the central limit theorem, the reason the bell-shaped curve turns up everywhere. He later found out that the Finn Jarl Lindeberg had already proved it in 1922.

That same year he attended a course by Max Newman on the foundations of mathematics and heard of a question posed by David Hilbert: is there a mechanical procedure that can decide whether any mathematical statement is true? To answer it, Turing had to say what a “mechanical procedure” is. The answer was the Turing machine, and the conclusion was that such a procedure does not exist.

The paper was ready in May 1936. A few weeks earlier, the American Alonzo Church had published the same result by a different route. Turing then went to Princeton to do a doctorate with Church and returned in 1938.

Bletchley Park

On 4 September 1939, the day after Britain entered the war, Turing reported to Bletchley Park, a country estate where the government was gathering mathematicians, linguists and chess players to read German messages. There he headed Hut 8, in charge of the naval Enigma, the hardest of all. He designed the electromechanical bombe that tested thousands of keys an hour and invented a statistical method, Banburismus, to save the bombes’ work.

His colleagues remembered the eccentric who chained his mug to the radiator with a padlock and cycled in a gas mask because of his hay fever. In 1941 Turing and three colleagues wrote directly to Winston Churchill asking for more staff. Churchill replied with an order: “Action this day”. For his war work Turing was appointed to the Order of the British Empire in 1946, but he could not tell anyone why. The secret lasted until the 1970s.

The first computers

After the war, at the National Physical Laboratory in Teddington, Turing designed the ACE, an electronic computer that kept its program in memory, like the universal machine of the 1936 paper. The project fell behind, and in 1948 he moved to the University of Manchester, where one of the first computers in the world was running. He wrote the programming manual for the machine, including an instruction to make it play notes, from which came some of the first music played by a computer, and with a friend he created a chess program that he carried out by hand himself, for want of a machine fast enough.

In 1950 he published the paper on the imitation game and, in 1952, the theory of morphogenesis. In 1951 he had been elected to the Royal Society.

The conviction and the death

In January 1952 Turing’s house in Wilmslow, near Manchester, was burgled. When he told the police that the burglar was an acquaintance of a man with whom he was having a relationship, Turing ended up charged with “gross indecency”: relations between men were a crime in England. He pleaded guilty and, to avoid prison, accepted a year of treatment with female hormones. He lost his clearance to work on state secrets.

He went on working in Manchester. On 8 June 1954 his housekeeper found him dead at home. The inquest concluded that he had taken cyanide and recorded suicide. There was a half-eaten apple beside the bed, which was never tested. His mother always maintained it had been an accident with the chemicals from his experiments.

Sources: Andrew Hodges, Alan Turing: The Enigma (1983) · Turing biography, MacTutor · The Turing Digital Archive, King’s College.

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