The Imitation Game

The first things to say about this film is that it is well worth seeing, profoundly moving and (in general) very well acted.

The second is that it gets to be this way by rather playing with the facts.

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I am no Turing expert – I’ve read On Computable Numbers (via the quite brilliant The Annotated Turing), Computing Machinery and Intelligence and listened to the audio book of Alan Turing: The Enigma (now subtitled “the book that inspired the film The Imitation Game”) but I know enough to doubt that there really was a late-night post-boozing moment when the bombe machine started to work (this appears to be an attempt to lump the success of the bombe and Turing’s insight into German naval codes into one gloriously cinematic moment) and I certainly know that Turing did not spend – as the film implies if not explicitly states – the whole of the war at Bletchley Park.


And the film does Turing’s co-workers a great dis-service when it implies that Turing alone wrote to Churchill and that Turing then used the letter’s success to dominate his co-workers. The letter was written collectively and,  what is more, after the first bombes were working, not as a device to get a bombe built.


Nor is the film fair on Turing in the sense that he is portrayed as – and the title implies he was adept at – hiding his sexuality. If anything it was Turing’s unwillingness to hide that caused him so much trouble. He was not ashamed to be gay (a word he used) even if some simulation just might have helped him dodge his indecency conviction.


No matter, though, the spirit of the film is correct and Cumberbatch is excellent in the lead role. Though it was Keira Knightly playing Joan Clarke who, if anything, impressed me more (though her accent seemed to swing back and forth between very posh and modern classlessness). Perhaps that is because Joan is now rather more of an enigma than Alan.


Reading this morning’s papers about the film it was implied that Turing’s work was not given due credit until recently because he was gay. I am not sure that is true.


We should not really expect the majority of the public to have heard of the “Church-Turing thesis” or to have grasped the basics of a Turing Machine, though the increased pervasiveness of computing devices does mean that Turing’s name as a key founder of the theoretical basis of electronic computing has become more widely known regardless of attitudes towards homosexuality. The Ultra decryption effort was kept hidden until the late 70s and the full details took some time to come out, but the ACM‘s Turing Award – the highest that a computer scientist could hope for, has been in existence since 1966: computer science did not disavow him.


But his story is a reminder of how bigotry damaged so many lives – even those to whom we owe so much.





The Great Alan Turing

Allan Turing Statue, on display at Bletchley Park
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Slashdot have a story to the effect that Leonardo DiCaprio is to play Alan Turing in a film that will mark the mathematician’s centenary next year.

Great news – the man’s memory deserves nothing more than the actor who has proved himself to be both great and edgy in recent work (he’s certainly not the milque toast figure the start of his career briefly suggested.)

As a geek, of course, I hope that the film will try to explain, just a little his achievements.

But how can you explain the ideas of computability and the Church-Turing thesis in a popular film? A tough one, but I suppose you could do something.

The Bletchley Park “bombe” and the idea that the weakness of the German Enigma machine – that it would never map a letter to itself (eg., in any message “e” would never be encrypted as “e”) – could be used to break the code (if a combination of a guessed plain text, usually a weather report, at the start of the message , and the initial key settings produced code that mapped letters to themselves then the initial settings were wrong) – is probably easier to explain.

And don’t forget about SIGSALY, the voice encryption system Turing worked on with Bell Labs. As a piece of engineering this is probably impossible to over-estimate in importance: as the first practical pulse code modulation system it could even be said to be the mother the mobile phone, or at least its grand aunt.

And, of course, let me again plug my book of the year: The Annotated Turing: A Guided Tour Through Alan Turing’s Historic Paper on Computability and the Turing Machine