1912: Alan Turing, who will go on to become one of the 20th century’s greatest mathematicians, computer scientists and philosophers, is born.

Turing is probably best known to Wired readers as the inventor of the “Turing test,” a way of measuring a computer’s ability to simulate intelligent human conversation.

But he’s more significant as one of the most influential computer-science pioneers of the 20th century, the man who invented and formally described the concept of a universal computing device, now known as a Turing machine.

He’s also a genuinely interesting figure, albeit a tragic one. An eccentric who liked to bicycle while wearing a gas mask and who occasionally wore pajama tops underneath suit jackets, he was also a prodigious and eclectic genius. He was elected a Fellow of King’s College, Cambridge University, just four years after entering as an undergraduate. Imagine enrolling at Harvard at 19 and becoming a faculty member in the mathematics department at 23, and you’ll have an idea how sharp he was.

A nearly Olympic-class marathon runner, Turing’s best time was 2 hours, 46 minutes, 3 seconds (by comparison, Delfo Cabrera won the 1948 Olympic marathon in 2:34:52). Yet, he was bookish, retiring and solitary in his study habits.

Turing was also a gay man in an era when homosexuality was not just taboo, but illegal. He was punished for his homosexuality in 1952 under the same 1885 law that had brought down Oscar Wilde more than half a century before. In lieu of a prison term, Turing was sentenced to a year of hormone “therapy” — basically, chemical castration with estrogen treatments aimed at curbing his sex drive.

Intellectually, Turing’s work defies easy categorization. He was influenced by Bertrand Russell and the circle of progressive intellectuals around John Maynard Keynes at Cambridge. His earliest work was mathematical, extending Kurt Gödel’s proofs that any mathematical system must necessarily be incomplete. But in solving that problem, Turing invented the notion of a universal machine, a now-fundamental concept in computer science.

A Turing machine is a device with an infinitely long tape, which it can use to write, read and alter arbitrary symbols (such as 1s and 0s). Starting with a basic set of operations, even the simplest Turing machine can be used to compute anything that is computable, Turing proved.

Interestingly, Turing machines can be used to simulate the behavior of other Turing machines — much as emulators let today’s Windows PCs play the same code that used to run on coin-operated Atari consoles in the 1980s.

After completing a Ph.D. at Princeton in just two years, Turing went on to play a pivotal role in the codebreaking work at Bletchley Park in England during World War II, cracking the code of the German “Enigma” cipher machine. After the war, he designed an ambitious computer, but the machine was never built.

Unfortunately, Turing’s work wasn’t widely recognized during his lifetime, in part because so much of it was done as part of classified government work.

In the last years of his life was working on what would now be called computational biology, using a computer to model how an organism’s genes manifest themselves in physical traits.

Turing died on June 7, 1954, in an apparent suicide. An apple found by the side of his bed may have been laced with cyanide.

It took more than 50 years, but in 2009, the British government apologized for the country’s appalling treatment of one of its great intellectual and wartime heroes. “It is no exaggeration to say that, without his outstanding contribution, the history of World War II could well have been very different,” then–Prime Minister Gordon Brown wrote. “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.”

The Alan Turing Year will commemorate Turing’s centennial in 2012 with a wide-ranging array of events.

For an accessible introduction to Turing, his concept of a Turing machine, and his contributions to artificial intelligence theory, check out the 4-minute video below from BCS, a British nonprofit.

Information Pioneers: Alan Turing from Information Pioneers on Vimeo.

Source: Various

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