Tuesday, October 28, 2014

Alan Turing

The other day, I started rereading Andrew Hodges' biography of Alan Turing, which I must have bought at least twenty years ago. This came about because last week I was reading Doug Hofstader's "I am a strange loop", which is about Gödel numbers (as much as it is about anything), and I remembered that Turing studied Gödel's work before publishing his famous 'On computable numbers' paper. Once started on Turing's biography, I then became interested in his short period at Princeton, which is when he completed his doctorate (now do you see the connection?). One of Turing's problems was that he didn't perform a literature survey: it happened at least twice that he independently discovered something that someone else had already discovered. Had he been more diligent, this wouldn't have happened. The book opines though that had he indeed performed the literature survey, he might possibly have not achieved the insights which he did in fact obtain. 

The fact that Turing often started from first principles, whilst ignoring prior work in the same area, paid back handsomely during his work on the Enigma: his fresh view allowed approaches to decoding the material which had never occurred to the Poles in their prior work on the Enigma, pre-World War II. To be fair to the Poles, they never saw Enigma in full use by a complete military machine, so some of the flaws would have been hidden from them.

This morning, I discover that Benedict Cumberbatch ('Sherlock', 'Tinker Tailor', etc) is portraying Turing in a film made of the biography: The Imitation Game.  I can hardly wait to see this film, although I do wonder how Turing's thinking (which is a lonely occupation at best) is going to be portrayed. 

If I recall correctly, Turing had already left the Enigma project by the time that Robert Harris' book "Enigma" takes place. The wiki states that "[Tom] Jericho is a doctoral student of the mathematician Alan Turing at a Cambridge college" before the war, although in real life, Turing never had doctoral students (he occasionally tutored undergraduates but was never a doctoral supervisor himself). Turing moved on when the decoding work on Enigma became 'industrial' and less needy of wizardly breakthroughs; he went on to work on building 'Delila', an invention far ahead of its time, which allowed digitisation of speech (or as we would call it now, both an A/D encoder and D/A decoder).

Then, of course, there was the computer, whose origins lie in his pre-war experience at building a differential analyser from gear wheels. Unfortunately, the British bureaucracy - which had been avoided to a certain extent during the war years - returned with a vengeance, and Turing never realised/was never allowed to achieve his full potential.

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