Things could have been very different. The Second World War may have lasted a lot longer than it did. Computers today might have been significantly different than they are, and the United Kingdom might well have became the world's computing superpower. Hyperbole aside, these statements say a lot about the impact of the "father of modern computer science", Alan Turing. His story is certainly worth retelling on his birthday today, June 23.
Alan Mathison Turing was born in 1912, the son of a civil servant, and showed remarkable mathematical and scientific aptitude as a boy which led his early educators to push him towards expensive 'public' schooling (private schooling for the rest of the world) to make the most of his talents. Ironically, this almost proved to his disadvantage - public schools at the time expected students to concentrate heavily on a classical education, and the thought that young Alan would become a "scientific specialist" rather than "educated" was viewed with considerable disdain. He was able to understand and even extrapolate Einstein's theories at the age of 16, but the classical requirement made school difficult. However, he found solace in his first love, Christopher Morcom, a fellow student at the school, who helped him make it to his final term at the Sherborne Schoool in Dorset. Morcom had suffered from bovine tuberculosis as a child and tragically contracted complications in that final term - his death left Turing distraught and shattered his religious faith, becoming an atheist. He became even more unwilling to work on his classical studies, which cost him a scholarship to Trinity College, Cambridge, and ended up sending him to his second choice, King's. He graduated with distinction in 1934 and became a Fellow there in 1935 for his mathematical work.
In 1936, Turing wrote his momentous paper "On Computable Numbers," where he formalised the computing concept of an algorithm with what are now called Turing machines. It's worth remembering that the notions, possibility, and potential of computers at the time were yet to be realized. Many had theorized and even designed programmable machines, such as Charles Babbage's famous Analytical Engine over sixty years earlier (and, in fact, Heron of Alexandria's creations almost two millenia before), but it was still unknown what value such a machine would have. Complex calculation feats were done by hand, and attempts to automate them required the construction of custom machines for each problem. If the problem changed, a new machine had to be built. The concept of a general-purpose machine was appealing, but none knew whether the engineering complexity would be worthwhile - such a machine would surely require unearthly amounts of maintenance, and, most worryingly, if a later problem came along which the machine could not solve, then the construction would have been in vain.
Turing's solution of this until-then open question was ingenious. Instead of trying to determine upfront whether a particular machine could solve a particular problem, Turing considered what the simplest possible computing device would be - a list of symbols on a strip of paper or tape, which could be read by a single sensor which would interpret the symbols as instructions to move the paper or rewrite the symbols. The device thus has everything a classical computer design would need; program and storage. The set of calculations such a machine could perform are known as Turing computable, and that covers all but the most pathological. If any computer is constructed, provided it could simulate this ideal machine, then it could solve that enormous range of problems - without needing to consider the individual valves and circuits that make up its design. This work led Turing to Princeton, where he studied under Alonzo Church, who also at the same time was working on these new notions of computability.
Nothing, however, could prepare anyone for the furious and unprecedented acceleration of technology caused by the Second World War. There was an obvious demand for mathematicians and computing machinery in order to break the codes of enemy communications, and Turing reported to Bletchley Park, the wartime code-breaking headquarters, the day after war was declared. Turing's work at Bletchley Park remained a secret for many years but is now almost the stuff of legend. Turing designed the electromechanical machine that made breaking of the "Enigma" codes feasible, intercepting huge amounts of encrypted enemy messages - over two hundred of these machines went into operation, using a method of Turing's that made a seemingly-impossible decryption task tractable. It's impossible to estimate how enormous an impact this had on the war effort - but 63 million characters of secret messages were intercepted. He visited the United States again in 1942 to assist in the construction of more decryption machines in Washington. At the end of the war, he was awarded the OBE for his "wartime services", although the classified nature of his work remained secret for many years. The Bletchley Park site is sadly in considerable disrepair, yet, for computer scientists around the world, it remains as significant a monument as Stonehenge, or the pyramids of Giza.
Following the war, Turing proceeded to assist in the construction and development of some of the world's first "true" programmable computers, and continued with his research. It's only become clear in recent years with the declassification of secret papers just how far Turing's inspiration had taken the British computing efforts - without a doubt, the UK led the world in the research and construction of computers of the era, albeit behind closed doors. One major open question remained from his previous work on determining what these machines could calculate; whether or not they could actually think. In 1950, he proposed what is now known as the Turing Test, the benchmark for a machine to be considered "intelligent". Turing suggested that if the machine was convincing enough to appear human, then it could rightly be considered intelligent - furthermore, there was little sense in trying to simulate a fully-developed adult human mind, but instead it might be more feasible to develop a childlike mind that would be capable of learning. The test still remains as the ultimate goal of artificial intelligence efforts.
Tragically, Turing's personal life was to cast a long shadow. Homosexuality was considered more than just grounds for dismissal from the military and exclusion from espionage activities in 1950's Britain. High profile cases (such as Burgess & Maclean) had produced public outcry that homosexuals would be more vulnerable to blackmail and entrapment (I leave the reader to spot the obvious flaw in this reasoning). However, again perhaps incredibly, homosexual acts were still illegal in the UK at the time, and considered evidence of "mental illness" that could be "cured" (typically by chemical castration). Turing had even entered into a short-lived engagement with a female co-worker at Bletchley Park, presumably in an effort to conceal his preferences from the military. In 1952, Turing's home was broken into by two young men, and later investigation uncovered that Turing had had a sexual relationship with one of the protagonists. Turing was charged with gross indecency (in much the same way as Oscar Wilde had been, over fifty years earlier) and had to choose between imprisonment or estrogen injections, which he submitted to for a year. His security clearance was revoked, and he was barred from further cryptographic work for the Government, and prevented from further discussing his work, including refusal of subsequent entry to the US.
Turing's death on June 7 1954 has almost become apocryphal. His cleaner discovered his body the following day; he had died from cyanide poisoning. A half-eaten apple lay on the table beside him, presumed the vehicle for the poision, although it was never actually tested. The death was ruled a suicide, although there are many theories that consider otherwise. His mother for instance argued it was an accidental death due to his concentration on chemistry in the last few years of his life and perhaps due to mishandling of substances in the lab; others point to the apple as a reference to Snow White, Turing's favorite fairy tale; and of course many consider the possibility of espionage and assassination. Whatever the truth, the importance of his ground-breaking work remains without doubt - the Turing Award has been presented since 1966, as the computing equivalent of the Nobel Prize. However, perhaps because of his sexuality, it has only been in the last decade or so that his country of birth has endowed upon him the respect, recognition, and tributes he so rightfully deserves.
Without him, things might have been very different indeed. We can only imagine what was lost with his premature death at the mere age of 41.
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