Earlier this year, the Science Museum held an exhibition called Top Secret: From Ciphers to Cyber Security. From World War One to the present day, the exhibition explored the many forms of communications intelligence that have been used throughout the century. Visitors were able to see examples of past and present gadgets, read declassified documents, learn about GCHQ (Government Communications Headquarters) and discover previously unseen artefacts. An exhibition about cyphers, however, could not be complete without a section about Alan Turing and the Bletchley Park codebreakers of the Second World War.
Turing c. 1928 at age 16
Alan Mathison Turing (1912-54) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist who is mostly remembered for his work with the Government Code and Cypher School (GC&CS) at Bletchley Park where he helped to crack Nazi Germany’s Enigma Code. The Enigma Machine scrambled the 26 letters of the alphabet so that the Nazi Party could send messages that could not be intercepted and understood. This resulted in pages full of gibberish, a bit like Ejwsf Zyhcx, which is supposed to be “Alan Turing” when put through an online enigma decoder.
Turing was born on 23rd June 1912 in Maida Vale, London, to Julius Mathison Turing (1873-1947) and Ethel Sara Turing (1881-1976). Turing’s father worked with the Indian Civil Service in Chatrapur, India, however, wished his sons, John and Alan, to be brought up in England.
From a very young age, Turing’s potential genius was evident and his parents enrolled him at St Michael’s day school in St Leonards-on-Sea, near Hastings where the boys stayed with a retired Army couple when their parents were in India. At 9, Turing began attending Hazelhurst Preparatory School before being sent to Sherborne School at the age of 13, a boarding school in Dorset. Although Turing’s aptitude for numbers was appreciated by the teachers at his primary school, it did not earn him any respect at Sherborne, where more focus was given to classical studies.
Despite his school’s attitude to scientific subjects, Turing went on to achieve first-class honours in mathematics at King’s College, Cambridge in 1934. The following year, he was elected a fellow at King’s and, in 1936, published his first paper On Computable Numbers, with an Application to the Entscheidungsproblem. Computable numbers were problems that could be solved by human mathematical clerks, who at the time were known as “computers”.
The Entscheidungsproblem (decision method) was proposed by the German mathematicians David Hilbert (1862-1943) and Wilhelm Ackermann (1896-1962) in 1928. They believed a machine could be invented that would be able to determine whether a mathematical statement could be proven. To put it more simply, “Is it possible to prove this mathematical statement?” The machine would respond with either a yes or a no. Turing, on the other hand, believed such a machine to be impossible.
A Turing machine realisation in Lego
Turing’s paper essentially pointed out that a manmade machine can only achieve what it has been programmed to do by a human. Since a human’s mind is limited, it would not be possible to produce a machine that could solve mathematical problems that a “human computer” could not. To illustrate this, Turing proposed a theoretical machine, now known as the Turing Machine, that could solve through the use of special symbols a mathematical statement that a “human computer” had the power to achieve too. The Turing Machine demonstrated the fundamental logical principles of the future digital computer.
After the publication of his paper, Turing continued to study, this time at Princeton University in New Jersey, where he obtained a PhD in 1938. As well as mathematics, Turing studied cryptology, which proved to be vital to his future career. Returning to England that summer, Turing joined the Government Code and Cypher School (GC&CS), now known as the Government Communications Headquarters (GCHQ). A year later, Britain was at war in Germany and Turing moved to the organisation’s wartime headquarters at Bletchley Park, Buckinghamshire.
Shortly before the Second World War officially began in Britain, the government had been given details from Poland about the Nazi Enigma Machine used to encrypt radio messages, which a small team of Polish mathematicians had succeeded in deducing. Led by Marian Rejewski (1905-80), the Polish cryptologists had developed a code-breaking machine called the Bomba, which helped them crack the Enigma code. Unfortunately, the German’s changed the code, rendering the Bomba useless.
Bletchley Park
Bletchley Park, once a Victorian manor house situated on 58 acres of land, was acquired by the government in 1938 for the GC&CS. Renamed Station X, Alan Turing was one of 200 workers to begin working there after the outbreak of war. Crossword experts and chess players were sought and hired throughout the following years to assist the decyphering work. By 1944, 9000 people were employed at Bletchley Park, the majority being women.
Bombe machine
One of the first things Turing and his colleagues achieved was the Bombe machine, based on the details they were given about the Bomba. The Bombe successfully decoded large amounts of German military intelligence that had been encrypted by the Enigma, which was passed on to British army officials. As the team became more adept at using the machine, they were able to increase the number of messages they intercepted. Eventually, they were decoding 84,000 per month, which equates to two messages every minute.
As the personnel at Bletchley Park grew, the manor house became too cramped for everyone to work in comfortably. In order to accommodate people, machines, storage and so forth, dozens of wooden outbuildings known as Huts were constructed within the grounds. Turing and his associates worked in Hut 8, where they successfully cracked the Enigma code.
Enigma Cipher Machine
Since there was more than one Enigma machine, the code-breakers at Bletchley Park needed more than one Bombe machine. Unfortunately, there was a lack of sufficient resources to build the machines. In 1941, Turing wrote to Prime Minister Winston Churchill (1874-1965) to explain the situation and the importance of the machines. Churchill reportedly went straight to his chief of staff and gave the order to “make sure they have all they want on extreme priority and report to me that this has been done.”
Lorenz SZ42
Enigma was not the only type of machine the Germans used during the Second World War. The more sophisticated Lorenz cypher machine, nicknamed Tunny by the British, was used to transmit messages between the Axis countries. In 1942, Turing developed the first systematic method for breaking these messages.
The Tunny machine encrypted messages by converting individual letters into binary code, for example, A became 11000 and B 10011. To make the messages even harder to crack, the machine blended in other letters to mask the binary code.
William “Bill” Tutte (1917-2002) was the first at Bletchley Park to notice a systemic pattern in the code and began to identify the letters that did not belong to the encrypted message. Building upon this, Turing developed a method of breaking these codes by hand, however, the process was slow and it was impossible for people to keep up with the number of messages they were intercepting.
Colossus Computer
In 1944, Turing had finally completed a machine that was able to help the team translate the Tunny machine. Known as Colossus, Turing’s machine was a form of early computer involving 1600 vacuum tubes. The machine’s job was to strip the surplus letters from the messages, after which they were passed onto hand-breakers to translate the remaining code.
By the end of the war, there were nine Colossus machines, or Colossi, which helped to speed up the decryption process. The messages sent out by the Tunny machine revealed the German army’s plans, positions, supplies and conditions. The intelligence gathered was crucial to the success of the Normandy D-Day landings on 6th June 1944.
All the operations that took place at Bletchley Park were kept secret, even after the war ended. It was not until 1974 that the world began to learn about their achievements. Nonetheless, Alan Turing was made an Officer of the Most Excellent Order of the British Empire (OBE) for his code-breaking work.
“It is a rare experience to meet an authentic genius … Alan Turing was such a genius, and those, like myself, who had the astonishing and unexpected opportunity, created by the strange exigencies of the Second World War, to be able to count Turing as colleague and friend will never forget that experience, nor can we ever lose its immense benefit to us.”
– Peter Hilton, British mathematician
After the war, Turing moved to Hampton in the London Borough of Richmond where he stayed until 1947. He had been recruited by the National Physical Laboratory (NPL) to create a digital computer. Turing produced designs for the Automatic Computing Engine (ACE), the first concept for a stored-program computer, i.e. a computer with memory. Although the concept was entirely feasible, the NPL thought it too difficult to attempt and built a smaller machine instead. As a result, Turing missed out on the opportunity to be the first person to create a digital stored-program computer. This honour was achieved by the Royal Society Computing Machine Laboratory in 1948.
Disappointed with the lack of ambition at the NPL, Turing moved to Manchester where he was appointed Reader in the Mathematics Department at the Victoria University of Manchester. The following year he became the director of the Computing Machine Laboratory where he helped work on another digital stored-program computer, the Machester Mark 1. He also designed the programming system for the first-ever marketable electronic digital computer, which was eventually built in 1951.
Turing is credited as a founding father of artificial intelligence and modern cognitive science. He proposed a test to determine whether a machine could exhibit intelligent behaviour, i.e. can machines think? The Turing Test, as it is now known, would distinguish original thought (human) from “sophisticated parroting” (programmed machine). Turing argued that a machine can only be called intelligent if it reacts and interacts like a sentient being.
The Turing test, nicknamed the “imitation game” involved a human and a computer to answer a set of questions. A human interrogator would then attempt to determine which answers belonged to which test subject. A computer’s intelligence was rated by its probability of being mistaken for a human.
Turing’s idea was inspired by a few philosophers, particularly René Descartes (1569-1650) and his famous statement, “I think, therefore I am.” Another philosopher, Denis Diderot (1713-84) stated, “If they find a parrot who could answer to everything, I would claim it to be an intelligent being without hesitation.” Turing believed by the year 2000 a computer “would be able to play the imitation game so well that an average interrogator will not have more than a 70-per cent chance of making the right identification (machine or human) after five minutes of questioning.” So far, no computer has come close to this standard.
Today, a reversed form of the Turing Test is regularly used on the internet. When logging into some websites, people are often asked to complete a CAPTCHA, which stands for “completely automated public Turing test to tell computers and humans apart”. This test usually requires someone to enter a sequence of slightly distorted letters and numbers. This is something a computer would be unable to achieve, therefore, humans are effectively being asked to prove they are not a robot. This prevents computer hackers from using computer software to break into people’s online accounts.
In 1948, Turing and his colleague David Gawen Champernowne (1912-2000) began writing a chess program for a computer that had not yet been produced. Named the Turochamp after its creators, the game was tested on existing computers, however, they lacked enough power.
In March 1951, Turing received his highest honour when he was elected a fellow of the Royal Society of London. Unfortunately, Turing’s personal life was soon under scrutiny and all his successes rendered meaningless.
Back in 1941, Turing had proposed marriage to Joan Clarke (1917-96), a colleague at Bletchley Park. The engagement, however, was short-lived, ending soon after Turing admitted he was homosexual. Joan was unfazed by the revelation and thought they could make their relationship work, however, Turing was too ashamed to go through with the marriage.
Being gay was no longer a punishable crime, however, homosexual acts were still a criminal offence. In 1952, it came to light that Turing was in a relationship with 19-year-old Arnold Murray and they were both charged with “gross indecency”. Turing was given the choice between imprisonment or probation, of which he chose the latter, however, his criminal record meant he could never work for Government Communications Headquarters (GCHQ) again.
By opting for probation, Turing had to agree to undergo hormonal treatment to reduce his libido. For a year, Turing was injected with synthetic oestrogen, which caused breast tissue to form and rendered him impotent. Although he had lost his security clearance, he was able to continue his academic work throughout this process.
Sadly, Alan Turing was found dead at the age of 41 on 8th June 1954. A post-mortem revealed he had died the day before as a result of cyanide poisoning. It is thought, although not proved, he had ingested a fatal dose of cyanide that had been injected into an apple. His death was recorded as suicide. Some biographers have suggested Turing was re-enacting a scene from his favourite film, Snow White and the Seven Dwarfs.
Some people have questioned the coroner’s verdict, suggesting Turing’s death was not suicide but an experiment gone wrong. Turing had set up an experiment in a small room in his house, which involved the use of cyanide. Turing may have inhaled a considerable amount of the poison during the day, causing him to collapse later that evening. Although a half-eaten apple was found at Turing’s side, it was never tested for traces of cyanide.
Generally, it is assumed Turing’s death was suicide, which is attributed to the hormone “treatment” he received at the hands of the authorities for being gay. Nonetheless, the injections had ended a year before his death and his friends claimed he was in good spirits. This cleared the authorities from any blame.
Naturally, conspiracy theories have evolved suggesting Turing was murdered by the secret services for knowing too much about cryptanalysis. At the time, homosexuals were also regarded as threats to national security, which adds a certain weight to this theory.
Regardless of the cause of death, Turing’s prosecution for being gay has become infamous, causing Prime Minister Gordon Brown (b.1951) to apologise for Turing’s “unfair treatment” on behalf of the British Government in 2009. Queen Elizabeth (b.1926) followed suit in 2013 by granting Turing a royal pardon.
“Thousands of people have come together to demand justice for Alan Turing and recognition of the appalling way he was treated. While Turing was dealt with under the law of the time and we can’t put the clock back, his treatment was of course utterly unfair and I am pleased to have the chance to say how deeply sorry I and we all are for what happened to him … So on behalf of the British government, and all those who live freely thanks to Alan’s work I am very proud to say: we’re sorry, you deserved so much better.”
– Gordon Brown, 2009
Since the 1990s, Alan Turing has been honoured in various ways, particularly in Manchester where he was working at the end of his life. In 1994, the A6010 road was renamed Alan Turing Way, and the bridge the road goes over is now known as the Alan Turing Bridge.
In 1999, the American weekly magazine Time listed Turing as one of the 100 Most Important People of the 20th century. The article pointed out that “The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine.”
On 23rd June 2001, the Alan Turing Memorial was unveiled in Sackville Park in Manchester. The sculpture, which depicts Turing sitting on a bench with an apple in one hand, was created by Glyn Hughes from cast bronze. On the bench, a series of letters reveal the phrases “Alan Mathison Turing 1912–1954” and “Founder of Computer Science” as though encoded by an Enigma Machine. “IEKYF RQMSI ADXUO KVKZC GUBJ” The plaque on the ground in front of the statue is written in English, saying, “Father of computer science, mathematician, logician, wartime codebreaker, victim of prejudice” This is followed by a quote from the philosopher and mathematician Bertrand Russell (1872-1970): “Mathematics, rightly viewed, possesses not only truth, but supreme beauty — a beauty cold and austere, like that of sculpture.”
To mark the centenary of Alan Turing’s birth in 2012, the Alan Turing Memorial was visited by the London 2012 Olympic Torch. It also came to light that Turing attempted to enter the previous London Olympics but lost out to other candidates. Yet, in 1948 he had finished a cross-country race ahead of the future silver medalist and his best Marathon time of 2 hours, 46 minutes, 3 seconds, was only 11 minutes slower than the winner in the 1948 Olympic Games.
In 2019, the Bank of England revealed Alan Turing will feature on the new £50 notes when they switch from paper to polymer in 2021. Turing was selected from a long list of experts from the field of science, including Mary Anning, Ada Lovelace and Charles Babbage, Stephen Hawking and Ernest Rutherford.
Thankfully, Alan Turing will be remembered for his achievements rather than the events that marred the end of his life. Turing has been immortalised in films, books and plays. He features in Ian McEwan’s 2019 novel Machines Like Me and inspired William Gibson’s 1984 Neuromancer. In 2000, he was the main focus of a Doctor Who novel, The Turing Test.
Alan Turing’s life was portrayed by Derek Jacobi in the stage show and film Breaking the Code, and in 2014, Benedict Cumberbatch starred as Turing in The Imitation Game with Keira Knightly as Joan Clarke, which focused on Turing’s success at Bletchley Park.
Dozens of universities across the world have statues of or rooms named after Alan Turing. He will always be remembered and admired by students, particularly those involved with mathematics, computer science and cryptology.
“We can only see a short distance ahead, but we can see plenty there that needs to be done.”
– Alan Turing
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Hazel Stainer 