
“The Imitation Game” and Alan Turing’s Real Contribution to Computing - johndcook
http://www.charlespetzold.com/blog/2014/12/The-Imitation-Game-and-Alan-Turings-Real-Contribution-to-Computing.html
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arketyp
I once read a proof of Gödel's first incompleteness theorem that used a
version of Turing's undecidability proof, which have had great impact on me.
That being said, I find the point of this article, if not nitpicking, then
asking too much of a Hollywood movie. I may be a bit cynical in suspecting
Petzold sees an oppurtunity here to Google rank his book.

With his famous paper, Turing (1) formalized the concept of the computation
and (2) showed, analogously to Gödel, that there are some facts about
computing that aren't reachable by computational means. He also did things
like _saving the world by decrypting the German Enigma machine_. Yet he was a
socially marginalized individual who died tragically because of it. I haven't
seen the movie, don't know what it's about. But I know it's not made for
computer scientists, and we should be glad that Turing is finally getting the
recognition he desereves.

~~~
Retric
_saving the world by decrypting the German Enigma machine_ this is often
repeated but mostly incorrect statement. Marian Rejewski, Jerzy Różycki and
Henryk Zygalski cracked v1 of the enigma in theory. So, Brittan was provided
with full pictures of the insides plus an approach to crack it by some polish
mathematicians, but they needed to build some actual physical devices. Also,
the enigma design continued to be improved upon over time, but the basic
approach more or less continued to work.
[http://en.wikipedia.org/wiki/Marian_Rejewski](http://en.wikipedia.org/wiki/Marian_Rejewski)

PS: Remember home grown heroes get all the credit whatever their actual
contributions.

~~~
cmdkeen
The four rotor enigma change the Germany Navy adopted though was a significant
change - and the decryption of that was something Turing was heavily involved
in.

In 1942 the Battle of the Atlantic was far from undecided and without cracking
the naval Enigma it is entirely possible that Britain would not have been able
to effectively stay in the war, or send convoys to Russia.

~~~
dspillett
_> was a significant change - and the decryption of that was something Turing
was heavily involved in._

It was still much more of a team effort than usually presented though. It does
irritate slightly the way that people concentrate on the code cracking and
Turing as it seems unfair in to directions: it forgets the other people who
also contributed significantly, and pretty much ignores the significant work
that Turning _did_ do largely solo.

~~~
Florin_Andrei
It might be because Turing's groundbreaking theoretical work is beyond the
realm of comprehension for the vast majority of people.

There's only one person who became famous on the grounds that he's so great,
almost nobody even understands what he's done - and that's Einstein.

~~~
JoeAltmaier
He did a lot. Everybody understands the simple stuff - matter and energy are
the same thing - e=mc2

------
drzaiusapelord
This is why I think non-documentary movie making of the lives of historical
people is a fool's errand. Of course Hollywood had to sex up Turing. He's a
pretty boring guy by Hollywood hero standards. There was no big breakthrough
with the Enigma. Well, there was, but it was a Polish team that figured it
out. Obviously, his sexuality is a dramatic point in his life, but that's not
much to build a movie on. I really wonder if a decent documentary team was
granted 1/10th the budget of this movie, what would their output be? Probably
a decent and educational flick.

Its also a weird production. I'm not even sure who made this movie. It seems
that it was produced by a near non-entity called Black Bear Pictures out of
NYC, which shows only this movie and three others on their webpage. It was
directed by a nobody with 3 other mediocre films under his belt and written by
a novice writer. It really has "pet indie project of a wealthy person or two"
written all over it. Shame really, a more mature and historically serious team
probably would have punched out a better film.

There's a great Turing/Enigma/WWII film to be made, and this just isn't it.
Considering its poor box office response (only 1m so far), I imagine this will
be the only one, ever for Turing. I really feel his story is Spielberg or
Scorsese worthy, but now alas, Turing is established as box office poison.

~~~
melling
It looks like the movie is playing in only 8 theaters in the United States. I
saw it in NYC where it was only playing in 1 theater.

[http://www.boxofficemojo.com/daily/chart/?view=1day&sortdate...](http://www.boxofficemojo.com/daily/chart/?view=1day&sortdate=2014-12-09&p=.htm)

Sort by average and it wins. It was a very entertaining movie. It would do
well in a wider release.

~~~
underwater
It is being released more widely. From Wikipedia: "The film will expand into
additional markets in 12 December and will be released nationwide on Christmas
day".

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jimhefferon
To me,

> any conceivable mathematical calculation can be done by a single device
> shuffling 1’s and 0’s back and forth

seems right. It does not say that Turing's machine solves every problem. It
says it does every conceivable calculation.

That was Turing's contribution (anyway, one of them). The controversy at the
time (1930's) was that there were a number of proposed definitions for what
are conceivable mathematical computations (Kleene, Post, Herbrand ..). All of
them gave schemes that the authors claimed were exhaustive. Turing's paper
convinces a reader, as it convinced Godel, that his definition does indeed do
everything mechanically possible (and everyone else's definitions, since they
all prove to be equi-powerfull).

Of course Godel knew there were unsolvable problems. The question was whether
there was a single maximally-powerful device.

~~~
skywhopper
A Turing machine can compute anything that can be mechanically calculated, but
the key point here, which Godel proved, is that there are exist problems that
_cannot_ be mechanically calculated.

~~~
Florin_Andrei
If the brain is a computer, the implications are staggering. Basically, there
can be no Theory Of Everything. Instead, all we can hope for is a loosely-
coupled federation of local theories.

------
mabbo
“On Computable Numbers, with an Application to the Entscheidungsproblem” is a
hugely important work, and Petzold's book "The Annotated Turing" makes it very
accessible. I highly recommend anyone who is interested pick up a copy. High
school education is all that's really needed.

Turing was decades ahead of the rest of us. It's a shame that we're portraying
him so inaccurately (though really, not nearly as shameful as how we treated
him when he lived).

~~~
termain
"Turing was decades ahead of the rest of us."

That seems unfair to Alonzo Church.

~~~
peterfirefly
And Emil Post.

------
jgrahamc
This is true, but there are so many other things horribly wrong with that film
that it hardly seems worth mentioning that they screwed up the description of
the Turing Machine's capabilities.

~~~
tokenadult
What other things do you find wrong with that film? Do you think that the film
detracts from the story of Turing's life, overall, or are the things wrong
just Hollywood repackaging of a story that is still told in a meaningful way
in the film? I'd like to support a movie that represents Turing's life fairly,
but the film hasn't opened here yet, so I haven't had a chance to see it.

~~~
jgrahamc
1\. Turing did not write by himself to Churchill and get himself put in
charge. He wrote with others and asked for more resources.

2\. Pretty much all sequences with the Bombe are a cringe because they appear
to be building a machine but not know what it is for. It's implied that it's a
Turing Machine.

3\. They apparently hadn't thought of using a crib resulting in a dramatic run
back to Bletchley from the pub sequence to get the Bombe working.

4\. John Cairncross didn't work in Turing's group. So the whole plot with
Cairncross and Turing and blackmail is nonsense.

5\. Gordon Welchman doesn't appear in the film and Hugh Alexander is instead
credited with coming up with the Bombe diagonal board.

6\. Turing is shown building a computer in his home in the early 1950s. Not
likely.

7\. Turing never told a Manchester police officer his entire life story
revealing all of Bletchley's secrets. Also, he didn't try to stop the police
investigation. He's the one that reported the burglary.

8\. Joan Clarke wasn't recruited through a crossword competition, she was
already known to be a bright mathematician.

I could go on.

Of course, none of this had to happen. I met the director and offered (for
free) to help them get stuff right.

~~~
chriswarbo
This is why we can't have nice things.

These kinds of criticisms seem little more than trying to jump on an SEO
bandwagon. It's important that the true accomplishments, history and
acknowledgements are understood by the writers and others working on a
production like this, but it does _not_ matter so much that the film portrays
exactly these. Just like SciFi writers should understand what is and is not
possible, but are free to relax those limits in their stories.

Firstly, it is not a documentary, it is a work of fiction which is "based on a
true story". Secondly, we're not watching presenters telling us what's going
on; we're watching actors playing characters. With that in mind, when I
watched the film I not only enjoyed it immensely, but I also found it
completely clear that the writers had their facts straight. I didn't once
cringe at the presentation, which I often do when non-experts describe
something technical which I understand.

As for your individual points:

1) The intention of having Turing write to Churchill was to establish the
(partially subconscious) arrogance of the Turing character, and his logical
approach to solving problems. Mentioning Churchill's involvement at all gives
the audience a clue to the importance of the work, which might otherwise be
seen as conscription-dodging. This was more important for the film than making
a realistic portrayal of the process of resource aquisition in wartime
Britain.

2) There was definitely the feeling that nobody understood Turing's exact
approach when he was _designing_ the Bombe, but during the construction phase
the only sense of confusion I got was whether their time was better spent on
Turing's unproven machine or on their known, but inefficient manual
approaches.

The character of Joan _guesses_ at one point that Turing is _trying_ to build
a Universal Turing Machine. There is no mention whether the Bombe itself is or
is not such a machine, but as the film progresses, we see post-war Turing
working on another machine which is most likely universal (presumably the
Manchester Mark 1 or one of its successors). The Bombe was clearly a stepping-
stone to get to this later machine, just as Turing hints that this machine is
just a stepping-stone to some later, "smarter" machine. There is a strong
implication that Turing's character doesn't regard these machines as distinct
devices, but as the continual "upgrade" of the same core concept. That his
first iteration wasn't universal doesn't matter.

3) Artistic license. The audience mustn't be bombarded by too many encryption
concepts early on, but the story much march ahead, so why not use each one as
a plot device?

4) It makes the film more interesting though. Again, it's not a documentary.
It does give a sense of the paranoia of the period, and the
double/triple/quadruple bluffs work very well to portray the intelligence of
the characters, especially that Turing can't just think his way out of his
problems (which is important, given how much Turing's intelligence had been
put across earlier). This changes the character of the film from superhero
Turing saving the day with his super brain, to a dangerous and intricate game
between _very_ capable people.

5) The fact it was mentioned at all shows that the history was known. The
theatrical intension is clear: Turing's character needed the help of his team,
even if he would not admit it. This minor plot point could be established
without bringing in a new character for the audience to keep track of, so the
attribution was shifted on to an existing character. Again, not a documentary.

6) That scene works well in his home, and benefits from the presence of the
machine. It would be awkward to interrupt the conversation while they pop down
the road to the University where it would have been in reality.

7) How else could it be told to the audience? Should Turing have been talking
to himself while out on a run? The police interrogation provides a context for
telling the story in the first place, as well as an impending darkness that
it's not all going to end well (else he wouldn't be getting investigated).
Having a bunch of eminent historians and scientists doing talking-head
sequences interspersed with CGI infographics only works for documentaries.

8) The crosswords are a useful plot point, can be related to by the audience
(using competitions to recruit secret spies would be especially effective at
inspiring children) and are a nice little piece of trivia. The fact that they
weren't very useful kind of ruins it though; hence they invented a use by
recruiting the Joan character that way. Also, this allowed the contemporary
marginalisation of women in computing to be projected into the film; she is
forced to prove herself to the doubtful men.

I think it is an excellent film, and it spreads knowledge of the nature and
importance of the work done by early computer scientists, and hopefully gives
some people the inspiration to carry on that work (Computer Science, not
GCHQ!). It is not a reference book; very few will even remember the kind of
minutiae pointed out here. It's better to bring a lot of people most of the
way to the truth, in a way that they enjoy; than to squabble over the last few
mm, alienate almost everyone, present the field as toxic and jaded and make
those few who stick around miserable.

~~~
brianmcc
>> These kinds of criticisms seem little more than trying to jump on an SEO
bandwagon.

Wtf? Do you realise this is the jgrahamc who successfully campaigned for the
Prime Minister of the UK to finally apologise for Turing's treatment? Frankly
if anyone's entitled to adjudicate here, he is. I note that jgrahamc isn't
criticising the film or its aims, rather questioning why single out one aspect
when so many others have been given similar manipulation, and responding to a
_direct request_ for expansion on said "tweaks". I for one say thank you
jgrahamc.

------
scott_s
This is a good essay, and I am hesitant to see the film because I am worried
that I will cringe every few minutes. But, I disagree with this sentence:

"Everyone agrees that Alan Turing is a seminal figure in the computer
revolution, so it's puzzling why these movies deliberately misrepresent his
work."

I sincerely doubt the movies _deliberately_ misrepresent his work. Rather, I
assume they _honestly_ misrepresent his work, meaning that they tried to get
it right, but they don't understand it well enough to do so.

~~~
gone35
_I sincerely doubt the movies deliberately misrepresent his work. Rather, I
assume they honestly misrepresent his work, meaning that they tried to get it
right, but they don 't understand it well enough to do so._

Well, movies _deliberately misrepresent everything_ , all the time --it's
called artistic license! Accuracy (scientific or otherwise) is always a
distant second to cinematic flair, or whatever is it studios are trying to
optimize.

~~~
saraid216
Yup. That's why R'as al Ghul dies.

------
BruceIV
Odd that an article so nit-pickily concerned with the accuracy of the
mathematics of Turing's work would over-generalize the actual computation he
proved to be impossible, which was deciding if an arbitrary algorithm
terminates on all possible inputs (i.e. there are no infinite loops), to
"there are no bugs".

The Annotated Turing is a great book though, I highly reccomend it (Turing's
original paper is _very_ dense).

~~~
j2kun
What do you mean by over-generalization? If you could solve the problem of
determining if a program has a bug, you could solve the Halting problem. So
it's just a generalization. Maybe it could be formalized more technically, but
that makes it imprecise, not inaccurate.

~~~
svantana
Halting has nothing to do with being bug-free -- lots of buggy programs halt,
and some obviously bug-free programs may not halt (e.g. a brute force search
to determine Goldbach's conjecture)

~~~
j2kun
Of course it does: checking for halting _reduces_ to checking for bug-
freeness. See the other comment in this thread.

------
j2kun
Considering the budget for these kinds of things, I'm shocked they don't just
pay some theoretical computer scientists to read the script and provide
feedback on the mathematical correctness of the lines. You don't even need to
find _great_ computer scientists; you'd root out this bug with graduate
students.

~~~
mikeash
Many productions _do_ hire expert advisors. Various iterations of Star Trek
had a real scientist at hand to ensure accuracy. Tons of bad science slipped
through anyway.

The monetary cost is small, but the time cost can be big. Writer time and
attention is a scarce resource and time spent rewriting scripts for accuracy
is time not spent polishing them for other things. And the simple fact is that
scientific accuracy doesn't really sell. A movie with an otherwise good script
that contains bad science will do far better than a movie with an otherwise
bad script that contains good science. There isn't even much reason to think
that improved science improves viewership _at all_. As far as I can tell,
those productions that made attempts to portray accurate science did so
because the people involved genuinely wanted to.

Nerds flock to Star Trek and Star Wars and Gravity and other such movies even
though they're full of problems. And if we're really being cynical, every "the
problems with the science in Movie X" article written is just more free
publicity for it.

------
richieb
The New Yorker had a pretty good review of this movie:
[http://www.newyorker.com/magazine/2014/12/01/keeping-
secrets...](http://www.newyorker.com/magazine/2014/12/01/keeping-secrets-2)

