This Month in Physics History

January 23, 1952: Alan Turing's house is burglarized

On January 23, 1952, British mathematician Alan Turing returned home to find that burglars had broken into his home. Turing admitted in a letter to a friend at the time that none of the stolen items were irreplaceable, although he expressed an understandable sense of personal violation. It soon became very personal indeed. What should have been a minor annoyance and disruption ended up profoundly changing Turing's life — a life that, until then, had been marked primarily by professional accolades and success.

Turing was born in London in 1912. Although his father, Julius, was a longstanding civil servant based in British India, Turing's parents wished to raise their growing family in England and moved to Maida Vale in west London. They continued to travel extensively, often leaving Turing and his older brother, John, with neighbors; school holidays were spent in the family home in Guildford. The young Alan showed academic promise at a young age, and at 13, began attending the Sherborne school in Dorset. So eager was the boy to learn, that when a strike shut down transport in Britain, he rode his bicycle the 60-mile distance, stopping just once at an inn for the night. That enthusiasm for physical activity stayed with him; he was a gifted long-distance runner, more than capable of the 40-mile distance to London from Bletchley Park during World War II.

Turing's gifts lay in math and science, but at Sherborne, the emphasis was on a traditional classics education, which led to conflict with a few of his instructors, but on the whole, he flourished intellectually. This was also where he met Christopher Morcom, an upperclassman who became Turing's first love — although his romantic affections were not returned. Morcom died of tuberculosis in 1930. Turing was devastated, and became an atheist, with a resolutely materialistic view of the universe, although he clung to the possibility that some part of his friend might live on. Some have speculated that this loss later influenced his thinking on the potential for artificial intelligence.

Having become interested in science through books by physicists such as Eddington and Einstein, Turing studied mathematics at Cambridge University, where he first encountered the work of American computer pioneer John von Neumann, among other intellectual influences. As a postgraduate fellow, he wrote an intriguing paper outlining ideas that would become features of modern computing. His mathematical gifts and abiding interest in cryptoanalysis snagged him a job with the Government Code and Cypher School in 1938 and eventually brought him to the now-famous Bletchley Park facility dedicated to cracking the German Enigma code, where by war's end he was one of nine thousand employees. His colleagues called him "Prof," and found his quirky eccentricities endearing, such as chaining his mug to the radiation pipes so that nobody would steal it.

Turing worked in Hut 8, the section assigned to cracking naval codes, even heading up his division for a time. Turing made several vital contributions to the cryptoanalytical war effort–including a portable secure voice scrambler nicknamed Delilah — but he is most famous for the Bletchley "bombe": a machine capable of deciphering the settings for the Germans' Enigma machine. More than 200 such machines were in operation by the end of the war, sounding like "a thousand knitting needles" when running.

Once the war ended, Turing worked at the National Physics Lab (NPL), developing early designs for a stored-program electronic computer. Much of his wartime research was classified, however, and Turing felt his achievements were not appreciated because of that continued secrecy. He left the lab in 1948, although the NPL did exhibit a prototype ACE computer in 1950 based on his design.

Turing was resolutely discreet about his private life, although close friends knew he was homosexual. He once proposed to his fellow Bletchley Park cryptologist, Joan Clarke, but broke it off when he realized he couldn't go through with the marriage. (Clarke was purportedly "unfazed" by his sexual orientation when he confessed it.) A few weeks before the 1952 burglary, he had met 19-year-old Arnold Murray, and the two men became lovers. Murray confessed that he knew the burglar when Turing confronted him.

An emotional Murray threatened to tell police about their relationship if Turing reported it — no idle threat, since homosexuality was a criminal offense in Britain at the time. Turing refused to be bullied into silence, although he initially withheld Murray's name and the fact that they were romantically involved. Eventually he was forced to admit the truth, and despite his prominence in British society, found himself on trial for "gross indecency." He pled guilty on the advice of his solicitor and was convicted in March, opting to undergo chemical castration in lieu of imprisonment. His elderly mother, Ethel, absorbed the shock and stood by her son, in sharp contrast to his brother, John, who denounced Turing's "disgusting and disreputable" proclivities.

Turing continued to do research during this stressful period, producing a fascinating paper on a possible reaction-diffusion mechanism for some patterns in nature, spurred by his interest in the prevalence of Fibonacci numbers in the structure of plants. But the hormonal treatments took a heavy physical toll, and his conviction severely limited his ability to travel, even for professional reasons. He also lost his security clearance, and thus was unable to continue his cryptography research.

On June 7, 1954, a cleaner found Turing's body in his home, with a half-eaten apple nearby. The coroner ruled his death a suicide by cyanide poisoning, although this remains a controversial finding. His mother insisted her son's death was accidental; Turing often ate an apple before bed. He also used cyanide in his home experiments and she had warned him about being careless in handling the poison in the past.

The laws used to convict Turing were not revoked until 1994, and on September 11, 2009, Prime Minister Gordon Brown made a posthumous apology for the mathematician's treatment, in response to a petition signed by thousands: "We are sorry. You deserved so much better."

Further Reading:

Hodges, Andrew. Alan Turing: The Enigma. New York: Simon and Schuster, 1983.

Levin, Janna. A Madman Dreams of Turing Machines. New York: Knopf, 2006.

Turing, Alan. "On Computable Numbers with an Application to the Entscheidungsproblem," Proceedings of the London Mathematical Society, 2d series, 42 (1936-37): 230-265.

Turing, Alan. (1952) "The Chemical Basis of Morphogenesis," Philosophical Transactions of the Royal Society of London B 237 (641): 37-72.