*The tragic loss of a friend during his teenage years exerted an extraordinary influence on Turing’s life, according to Roger Highfield and David Rooney.*

The defining moment of the remarkable life of Alan Turing, one of Britain’s most original thinkers, came much earlier than many realise. It was not while Turing cracked Nazi codes at Bletchley Park to change the course of the Second World War. Nor when he lay the mathematical foundations of modern computing. Or that instant when, during a 1951 visit to the Science Museum, he was fired up by the lifelike behaviour of a cybernetic tortoise.

The Museum’s Turing exhibition, which marked the centenary of his birth in 1912, showed that the signature moment of Turing’s life came on February 13, 1930, with the death of his classmate, Christopher Morcom, from tuberculosis. This shattering event propelled the great Turing through a remarkable career.

Morcom was Turing’s first love, a fellow, older pupil at Sherborne School, Dorset, who shared Turing’s passion for mathematics. Though Turing’s crush was not reciprocated, he was profoundly affected by the death of his friend. In a contribution towards an anthology for Morcom’s grieving mother, which is on display in the exhibition, Turing admitted that he ‘worshipped the ground he trod on’.

Morcom’s death cast a long shadow. Turing turned away from his Christian faith towards materialism, and began a lifelong quest to understand the tragedy. As he struggled to make sense of his loss, Turing pondered the nature of the human mind and whether Christopher’s was part of his dead body or somehow lived on.

Alan Turing is often portrayed as an isolated genius, even a borderline Asperger’s loner. This traditional depiction is, perhaps, a weak reflection of homophobia of recent decades. But read about his feelings for Morcom, his letters and the correspondence of those close to him and you obtain a more complete portrait. Far from being the insular genius of popular belief, Turing could be warm and gregarious, though he did not suffer fools gladly and had an original take on the way he lived his life as much as he conducted his science.

The October after the loss of his friend, Turing went up to Cambridge, where he studied mathematics. Our exhibition includes an essay, entitled “Nature of Spirit” that Turing wrote the next year, in 1932, in which he talked of his belief in the survival of the spirit after death, which appealed to the relatively recent field of quantum mechanics and reflected his yearning for his dear friend.

Around that time he encountered the Mathematical Foundations of Quantum Mechanics by the American computer pioneer, John von Neumann, and the work of Bertrand Russell on mathematical logic. These streams of thought would fuse when Turing imagined a machine that would be capable of any form of computation. Today the result – known as a universal Turing machine – still dominates our conception of computing.

Turing’s struggle to solve the codes of thought paved the way to his interest in cryptanalysis, the study of how to crack ciphers. Around the time of the Munich agreement in 1938 Turing began to help the UK government with the problem of deciphering German communication and this interest would culminate in an extraordinary effort during the Second World War when he worked for the Government Code and Cypher School at Bletchley Park.

There Turing would break the codes of society too. In 1941, Turing had proposed marriage to Joan Clarke, a fellow cryptanalyst, but decided he could not go through with the marriage after admitting his homosexuality to his fiancée, who was reportedly “unfazed” by the revelation.

Turing’s greatest challenge at Bletchley was the German enciphering machine, Enigma, three of which are on show in our exhibition (including one kindly lent by Sir Mick Jagger). He took particular responsibility for reading U-boat communications and led a team that designed the great ‘bombe’, a calculating machine that successfully decoded Germany’s wartime messages. Eventually, over 200 were built, each weighing a ton, that made the noise of a ‘thousand knitting needles’ when in full flight.

The breaking of the Enigma was vital, partly because it meant that the Allies could intercept messages to the U-boats that were attacking convoys, sinking merchant ships and threatening to isolate Britain. It’s even been claimed that, without Bletchley Park’s contribution, the war might otherwise have been lost.

At that time a ‘computer’ was not a machine but a person, often female, who did calculations by hand. Machines were used too, but only for defined jobs, such as aiming bombs or solving differential equations. Combining his ideas from mathematical logic, his experience in cryptology, and the remarkable code cracking machinery of Bletchley, Turing’s ambition was to create a computer in the modern, electronic, flexible sense.

He joined the National Physical Laboratory, NPL, in Teddington in 1945 where his detailed – and world-beating – plan for an electronic computer was accepted in March 1946. But by then his remarkable wartime achievements were a state secret and he was not taken as seriously as he deserved. Frustrated, Turing resigned in 1948 though eventually, in 1950, his ideas came to life at NPL in the form of the Pilot ACE computer, which is the star of the Museum’s Turing exhibition.

The machine was the fastest in its day. This remarkable testament to Turing’s inventive capabilities was in huge demand. Within the exhibition we show two vivid examples of how this pioneering machine was used: to reveal how metal fatigue caused the loss of BOAC Flight 781, a de Havilland Comet jet airliner; and the Nobel prize winning work by Dorothy Hodgkin to use X rays to unravel the molecular structure of Vitamin B12.

On Midsummer Day 1948, the first prototype general-purpose computer, a true universal Turing machine, went into action at Manchester. And it was at Manchester University, when Turing was Deputy Director of the computing laboratory, that he wrote his highly influential 1950 paper, “Computing Machinery and Intelligence.”

Turing had pondered how intelligence could arise in a machine, from operations which were themselves routine and, in a way, mindless. Perhaps it was possible to construct an artificial consciousness from blocks of cold mathematical logic.

He had a practical suggestion: if a computer could fool people into thinking that they were interacting with another person, rather than a machine, then it could be classified as possessing artificial intelligence. This simple idea has proved hugely influential. Since 1991, an annual competition based on the ‘Turing test’ has been held by the American inventor Hugh Loebner.

Turing was still haunted by the loss of Morcom. In his 1950 paper, he referred to research, perhaps by Samuel Soal in the UK, that there was ‘overwhelming’ statistical evidence of telepathy and remarked: “Once one has accepted them it does not seem a very big step to believe in ghosts.”

The next year Turing became interested in breaking the codes of life, furnishing a chemical basis for the means by which shape, structure and function arise in living things. It is known in biology as morphogenesis and had seemed so mysterious to some that it had fostered belief in vitalism, the idea that there was an élan vital that was distinct from physical or chemical forces.

Turing posed a basic question. How does an organism marshal a chemical soup into a biological structure or turn a spherical (symmetrical) bundle of identical cells into an (asymmetrical) organism? And why are there Fibonacci numbers (where each number is the sum of the previous two) in the leaf patterns of plants such as the close-packed spirals of sunflower heads? (our sister museum, the Museum of Science and Industry in Manchester, has carried out a mass experiment to investigate). Turing’s ideas have since led to some impressive descriptions of pattern formation in Nature, from snail shells to snake skins.

With the help of Age UK, the Science Museum has consulted lesbian and gay people who were alive in the 1950s to understand the moral climate. What became clear was that Turing was remarkably open about his homosexuality, despite the repressive attitudes of the day. Perhaps his logic and his honesty made him feel that his orientation could never be seen as a crime. After the sheltered, liberal environments of Cambridge and Bletchley, he was in for a shock.

Homosexuality was a criminal offence at the time and in February 1952 Turing was arrested for having a sexual relationship with a man, then tried and convicted of “gross indecency”. To avoid prison, he accepted treatment with the female sex hormone oestrogen: ‘chemical castration’ intended to neutralise his libido. In 2009 Gordon Brown, the then Prime Minister, issued a public apology for his treatment.

In that era, homosexual people were considered a security risk, being open to blackmail. Turing’s security clearance was withdrawn, so that he could no longer work for GCHQ, the post-war successor to Bletchley Park. He died soon after.

The precise circumstances leading to his demise on 7 June 1954, at home in Wilmslow, Cheshire, can never be known. But Turing had himself spoken of suicide and this was the conclusion of the coroner, following an inquest.

Next to Turing’s body was an apple, partly eaten. Years before, as some biographers have pointed out, Turing had gone to see Snow White and the Seven Dwarfs, the pioneering Disney film, in Cambridge, and was particularly taken with the scene where the Wicked Witch dangled an apple into a boiling cauldron: “Dip the apple in the brew. Let the Sleeping Death seep through”. One said that Turing had decided “to invest his departure from a world that had treated him shabbily with some of the gothic, eerie, colourful brilliance of a Disney film.”

The pathologist’s post-mortem report, reproduced in our new exhibition, suggests that the reality was more prosaic. The autopsy revealed that Turing’s stomach contained four ounces of fluid that smelt of bitter almonds: a solution of a cyanide salt. His death was not accidental: there was enough poison to fill a wine glass. Turing, thought the pathologist, had taken bites from the apple to make his last drink more palatable.

More than two decades earlier, when Turing was 17, he had had a vivid premonition of Morcom’s death, at the very instant that his first love was taken ill. Turing felt that this was an omen, one that lay beyond what science was able to explain.

Throughout his life he pursued the question of mind and body, believing that Morcom’s spirit lived on. Perhaps his suicide was one last experiment. On that cold, wet Whit Monday, did Turing take his own life in the hope that they would be together once more?

David Rooney is a Curator and Roger Highfield a Director at the Science Museum Group.

Codebreaker: Alan Turing’s Life and Legacy, opened at the Science Museum on the 21 June 2012 and ran until 31 July 2013.

## Ian Watson

Great article. I’ve just published a popular science book about Turing and his legacy called The Universal Machine http://goo.gl/Vn8Ab

I’d be very happy to arrange for my publisher to send you a review copy if you would like one.

Thanks for your time,

ian