It's pretty much what we know as the "Turing Test:" stick an intelligent something on the far end of a teletype circuit and try to figure out if it's man or machine.
It's also the title of an excellent film about Alan Turing, mostly his wartime experience at Bletchley Park and postwar conviction and suicide.
Turing's rehabilitation in recent years has been helped by the issue that ruined things for him currently being fashionable, but make no mistake: sure, he was gay, but ignore that and the man was still an oddball.
A genius oddball and there's the real point: growing up, I got to hang around with computer geeks back when you had to walk over to a terminal room and log on the mainframe and they all knew who Turing was: a computer pioneer. They knew all manner of interesting notions he'd put forward but you had to dig to learn how come he wasn't still around. The geeks didn't give a hang for his sex life and even with lingering wartime secrecy, they all knew he was one of the guys who got the whole "computer" thing rolling, one of the first people people who really grasped that all you needed was a machine that could precisely do simple operations rapidly, over and over, and you could get it to do anything computable, which turns out to be just about everything.
Just like many of the gang in the terminal room, he was awkward, impatient with fools, insightful, logical and intuitive. That's the fellow you'll meet if you go see The Imitation Game.
Benedict Cumberbatch does not look very much like Alan Turing -- and it doesn't make any difference; he steps into the character completely and from the first time he shows up on the screen, you're not looking at the guy who plays Sherlock Holmes in the BBC TV series, you seeing Alan Turing. It helps that all the little details in the film are as right as they can be. (The electromechanical decryption machine -- not Colossus -- used to read Enigma messages has been slightly rescaled for greater drama, but the components are right).
It's a good story, well-told. A bit complex -- at points, there are three timelines running and you do have to keep up -- but worth the effort.
Turing's story -- all of it, not just the made-for-tabloids ending but his real and valuable contributions to the bit-counting widgets inside everything these days -- deserves wider telling. The geeks never forgot him and with good reason.
ETA: New Yorker had an interesting review of the film, which addresses some of the ways in which the real story was telescoped for the screen and points up a few cultural false notes. Notably, the cinematic scene of exuberant celebration that punctuates the definitive cracking of Engima not only didn't happen, it simply would not have happened in 1940s Britain, not with that group (and generally, class) of persons. --Historical storytelling can at times be the art of telling truth by means of lies, of making the past decodable to the present; any time you point a camera at a subject, especially at some remove in time or place, you're faced with a series of choices about what to include, what to leave out -- and what to translate. With the pressure of time (decryption efforts at Bletchley Park having lasted a bit longer than a two-hour film) as well, you're going to get the occasional off note, a sharpening of drama, a narrowed view, a re-coding for the viewer. Given the subject and his work, it seems fitting.
8 months ago