Turing. Even if you don't know the man, you've heard the name. There's the Turing Machine: a mathematical model that defined early computing and modern day programming, and the more well-known Turing Test, an early definition of artificial intelligence. Most people with any interest in computing or robotics will have heard of the name Turing, but how many know the story of the man behind it all?
All photos from Wikimedia Commons
Turing was a British computer scientist, cryptanalyst, mathematician and, later in life, a theoretical biologist. He worked on breaking German ciphers during the Second World War, and thanks to this experience designing and building code-breaking machines, as well as his background in mathematics,he laid the groundwork for the first computers (in the modern sense of the term) to be built. Even more astoundingly, he constructed a framework for questioning the capability of a machine to be 'intelligent' even when such technology was still rudimentary.
A Scientific Specialist
From an early age, Turing's incredible intelligence was apparent to many of his teachers. At the age of 13 he moved to Sherborne School, an independent school in the town of the same name. His first day at this new school happened to be on the same day as the 1926 General Strike in Britain -- but he was so determined to go to this school that he rode his bicycle more than 97km from Southampton to Sherborne, even having to stop overnight along the way. Although Sherborne was a prestigious school, it was not always the perfect fit for Turing. The school placed a lot more emphasis on classical studies than the science and mathematics that Turing excelled at, with the headmaster even writing a letter of warning to his parents saying: "I hope he will not fall between two stools. If he is to stay at public school, he must aim at becoming educated. If he is to be solely a Scientific Specialist, he is wasting his time at a public school."
It was here at Sherborne that Turing developed a close relationship with his fellow pupil, Christopher Morcom. A known homosexual throughout his life, Turing would later encounter scandal due to his relationships with men, although his so-called "first love", Morcom died not much later due to complications from bovine tuberculosis. Although the event caused Turing to spiral into grief, he did not give up his work. A love of science and mathematics was one of the things that he and Morcom had bonded over, and so he poured more of his energy into these pursuits in honour of his friend's memory. In a letter to Morcom's mother, he says:
I am sure I could not have found anywhere another companion so brilliant and yet so charming and unconceited. I regarded my interest in my work, and in such things as astronomy (to which he introduced me) as something to be shared with him and I think he felt a little the same about me ... I know I must put as much energy if not as much interest into my work as if he were alive, because that is what he would like me to do.
A year later in 1931, he went on to study as an undergraduate at King's College, Cambridge, earning a first-class honours in mathematics in 1934. The following year, he was elected a fellow at the college after writing a dissertation on the central limit theorem. This would not be his last time in the academic world however, and his further studies would prove fundamental to the study of early computer science.
While Turing's earlier work had been impressive, it wasn't until 1936 when he made a breakthrough that would form the basics of his Turing Machine theory. He wrote a paper based on German mathematician David Hilbert's Entscheidungsproblem or 'decision problem' titled "On Computable Numbers, with an Application to the Entscheidungsproblem". The paper was based on Kurt Gödel's 1931 results, although Turing replaced Gödel's formal arithmetic language with the simple hypothetical devices that came to be known as Turing machines.
Simply put, a Turing machine is a hypothetical machine that can theoretically perform any computation that any other computing device is capable of. It's essentially a machine that runs on a tape which is made up of a series of cell. Each cell has a single character written on it. With each step, the machine looks at the symbol currently under it and decides what to do based on what it sees there and on the information it has stored. It has a few available functions: it can change the information it has stored, write a new symbol onto the tape or move one cell to the left or right. This concept is either very simple or very abstruse, depending on how much you know about computing, but Turing's model formed the basis for computer science long before the first general purpose computer was even built.
A modern model of a Turing Machine by Mike Davey
Turing continued his study at Princeton University in later years, obtaining his PhD from the university in 1938. His dissertation expanded on the theory of Turing machines, using so-called 'oracles' to facilitate a study of problems that cannot be solved by a Turing machine.
The Prof At Bletchley Park
"You needed exceptional talent, you needed genius at Bletchley and Turing's was that genius."
Bletchley Park was Britain's central codebreaking facility during the Second World War, regularly penetrating top secret Axis communications. Historians have estimated that the intelligence coming out of Bletchley during World War II potentially shortened the war by two to four years, and that without it the outcome of the war could have been uncertain. As someone with an interest in codebreaking and cryptology throughout his university studies, Alan Turing was a sure fit.
Turing allegedly reported to Bletchley Park the day after war was declared, quickly becoming central to the team. His major breakthrough was the bombe device, which was used to decipher messages encrypted by the German Enigma machine. The Enigma was one of the most complex encryption machines used in the Second World War, and Turing's device was a major victory for the Allies. His unique way of thinking -- analysing ciphers based on a process of contradiction -- was one of the major reasons the bombe was far more efficient than any other codebreaking machine. Jack Good, another cryptanalyst who worked with him, said of it:
Turing's most important contribution, I think, was of part of the design of the bombe, the cryptanalytic machine. He had the idea that you could use, in effect, a theorem in logic which sounds, to the untrained ear, rather absurd; namely that, from a contradiction, you can deduce everything.
The rebuilt Bombe designed by Turing
Turing was known to be eccentric to his colleagues at Bletchley Park, who called him 'Prof' and referred to his writings on Enigma as 'The Prof's Book'. Jack Good has been quoted as saying of him:
In the first week of June each year he would get a bad attack of hay fever, and he would cycle to the office wearing a service gas mask to keep the pollen off. His bicycle had a fault: the chain would come off at regular intervals. Instead of having it mended he would count the number of times the pedals went round and would get off the bicycle in time to adjust the chain by hand. Another of his eccentricities is that he chained his mug to the radiator pipes to prevent it being stolen.
While he is known for his work with computers, Turing was also a skilled long-distance runner who occasionally ran the 64km from Bletchley to London for high-level meetings. He even tried out for the 1948 British Olympic team, coming in only 11 minutes slower than silver medallist Thomas Richards -- and that was with an injury slowing him down.
During the war, Turing also worked on the difficult German naval Enigma, even travelling to the United States in 1942 to work with US cryptanalysts. He worked on a few other important projects before the end of the war, including a technique for use against the Lorenz cipher that was being used by the Germans, and a speech enciphering system codenamed 'Delilah' that was never adopted for use.
While Turing was awarded the OBE by King George VI in 1945, his work remained a secret, for obvious reasons, for many years after. His colleague at Bletchley, Hugh Alexander, said of Turing's many breakthroughs:
It is always difficult to say that anyone is 'absolutely indispensable', but if anyone was indispensable to Hut 8, it was Turing. The pioneer's work always tends to be forgotten when experience and routine later make everything seem easy and many of us in Hut 8 felt that the magnitude of Turing's contribution was never fully realised by the outside world.
The silence surrounding Turing's work during the war was due to the overall secrecy of Bletchley Park, rather that the controversy that he courted during his later life. He did propose marriage to one of his co-workers, Joan Clarke, during 1941, but the engagement was not to last. He broke it off after confessing his homosexuality to her -- although Clarke was supposedly "unfazed", he decided that he could not go through with the marriage.
Once the war had ended Turing turned his attention to computers, during a time when the first general purpose computers were only just being designed and built. The first computer, the ENIAC, was finished in 1946 and while Turing was not involved in its construction, much of his work provided the foundation for its design.
Turing did work on a design for the ACE, or Automatic Computing Engine, although the secrecy surrounding his wartime work at Bletchley led to delays on this project. When he returned to Cambridge in 1947 for a sabbatical year, the Pilot ACE was built in his absence at London's National Physical Laboratory. The pilot machine executed its first program in 1950, although sadly Turing did not live long enough to see the full version of the ACE built. In 1948 he did spend some time writing a chess program to be run on a computer that, at that point, didn't exist. By 1950 it was complete and like much of his work ended up adopting his name, or part of it, being dubbed the "Turochamp."
The Pilot ACE Commputer
It was in 1950 when Turing developed the work for which he is most known today -- the so-called 'Turing Test' that is said to be a measure of artificial intelligence. This test began its life as an experiment that Turing proposed, whereby a computer could be said to 'think' if a human couldn't tell it apart, through written conversation, from another human being. He even wrote theories on how to create such artificial intelligence, suggesting that a computer program could be written to simulate a child's mind and then educated to an adult level, rather than tackling the complexity of programming an adult's mind from the start.
The Turing test is iconic -- indeed, one iteration of it is encountered by most internet users on a regular basis in the form of a CAPTCHA, which is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart".
A Death In Disgrace
Despite his contributions to the war effort, to Britain and to computer science worldwide, Turing lived his last years in disgrace. In 1952, at the age of 39, he started a relationship with a 19-year-old man, although it was not until his house was burgled by an acquaintance of this man that his relationship became known. At the time, homosexual acts were criminal offences in the United Kingdom, and after admitting a sexual relationship with the other man during the investigation into the burglary of his house, Turing was charged with gross indecency.
He entered a guilty plea in the end and was convicted, avoiding imprisonment by choice of a probation whereby he was subjected to hormonal treatment -- a series of injections that would reduce libido. By all accounts, Turing took his treatments with good humor, being quotes as saying that "no doubt I shall emerge from it all a different man, but quite who I've not found out". As a result of the treatment Turing became impotent, and developed gynaecomastia. To add insult to injury, he was stripped of his security clearance and barred from continuing his cryptographic consultancy, even during the early years of the Cold War.
Two years after his conviction, Turing was found dead at the age of 41, with the cause of death being named as cyanide poisoning. A half-eaten apple was found by his body, and despite a friend of Turing's claiming that this was not unusual as he was in the habit of eating an apple each night before bed, this was latched onto as the sensationalised means by which Turing supposedly committed suicide. As with all mysterious suicides, there has been much discussion over whether Turing did indeed take his own life or not, with some speculating that it could have been inhalation of cyanide fumes from his experiments that killed him.
The Turing Legacy
A monument to Alan Turing at his former workplace at Bletchley Park
Much of Turing's work was not acknowledged until after his death, with some of his wartime work still held under the Official Secrets Act. In 1966, the Turing Award was established by the Association for Computing Machinery, which is widely considered to be the highest honour that can be received by any in the computing world, even being compared by some to the Nobel Prize.
It wasn't until 2009 that a petition was started and signed by more than 30,000 people, urging the British Government to apologise for the way Turing was treated during the last year of his life. It wasn't long before the government responded, with Prime Minister Gordon Brown acknowledging the petition and the "appalling" treatment of Turing.
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.
However it wasn't until July 2012 when a bill was introduced in the House of Lords to grant a pardon to Turing for the offences for which he was convicted. After another long wait, Queen Elizabeth II finally signed a posthumous pardon for Turing's conviction, which is only the fourth royal pardon granted since the conclusion of the Second World War. Justice Secretary Chris Grayling said of the pardon that Turing should be "remembered and recognised for his fantastic contribution to the war effort" instead of for his conviction and disgrace. The same could also be said for his work in the computer sciences -- although the fact that his name lives on in so many ways today is more important than any royal pardon ever could be.
These Are Your Numbers is a new Lifehacker series where we profile great minds that have made significant contributions to robotics and computing.