In 1936 a young man of 24 years took a long walk in the crisp air of the Cambridgeshire spring, and during that walk had an idea that changed the world. The idea was his answer to a question whose time had come: "What is a computer?"
The young man was Alan Turing, protagonist of a new film titled The Imitation Game. It tells the story of another world-changing feat of Turing's: During World War II he was the brains of a small army of geniuses who worked for the British military intelligence to break the Nazi code "Enigma" — a feat that went a long way towards winning the battle of the Atlantic, and perhaps even the whole thing. In the process, in 1943 they created the Colossus, the world's first computer similar to the one on which you are reading this: electronic, digital, and programmable.
The 'Turing machine' and the birth of software
In 1935, computers were just below the horizon, and many clever engineers and mathematicians around the world were wondering how to put one together. But Turing had a different take: what he wanted to do is prove that a computer, once constructed, will never be able to solve one particular problem in math: find proofs of theorems in first-order logic.
It's funny, when you want to establish that something cannot be done, only then are you forced to put your act together and define crisply what "done" means. This is how Alan Turing accomplished two momentous things at once: He solved one of the great mathematical problems of that era and, far more consequentially, he came up with an abstract device that would become the world's blueprint of the computer.
Through the "Turing machine," as this device came to be called, Alan Turing gave us the gift of universality. Of software. All the other computer buffs of the time were convinced that computers should be specialized to address specific tasks.
Today, when you stop responding to your email and you start editing a file, you don't change computers, you just load another piece of software. This was Alan's original idea. In the paper he wrote – considered the birth certificate of computer science – he created one particular Turing machine that could simulate all other Turing machines, if supplied with a description of that machine: a universal – programmable, that is – Turing machine.
(Incidentally, he did not need universality to prove his theorem, he seems to have done it for fun. My theory is, he was seeking a programming challenge worthy of his intellect. Don't many programmers nowadays come of age by writing a compiler?)
More intellectual feats
Alan Turing went on to other things. In "The Imitation Game," he saves the world through his code breaking. Earlier, at the age of 20, he was the youngest of the dozen or so mathematicians, all over the world, who independently came up with proofs of the central-limit theorem.
Much later, he defined and kick-started the field of artificial intelligence by coming up with an evocative role-playing game, to which I guess this film owes its title: How can a computer program convince you over the net that it is a person? Before that, he did ingenious engineering work with computers.
Turing also started the field of morphogenesis in developmental biology, which studies how patterns are formed in the embryos of organisms, how the spherical symmetry of the fertilized egg is broken to create an animal that is decidedly not spherically symmetric. How the tiger gets its stripes, so to speak. He identified a phenomenon in chemistry that is still called "Turing instability." When the pioneers of developmental biology started thinking about this question in the 1980s, they were astonished to discover that a British mathematician, 30 years earlier, had already articulated and answered it completely.
One man's passion
It is easy to read this list of amazing intellectual accomplishments, what is harder is to imagine the passion that drove the man. If you delve seriously into Turing's opus, into his impeccable, composed, and loudly self-conscious prose, what jumps out at you is his passion, his raw, unadulterated passion.
Let me insert here a passage adapted from my 2003 novel Turing . The plot is a fantasy; Alan is having a good time in the Internet, fiddling with the lives and the minds of two modern-day lovers, Ethel and Alexandros. This is Turing speaking:
I should now tell you why I lived my life the way I did. It's odd, how writing that Latin nonsense in the bottom of the page, QED, can make you feel the most intense, intoxicating pleasure, almost like love's tickle and explosion – no, even more exquisite and sweet than that. Except that theorems don't have the lovely lathed curves – neck, arm, and torso, red with excitement, throbbing with sweat – of a young athlete leaning on the oar after the race. A race that was a metaphor and prelude of the game starting next, a game of war where victory! you break the cypher, save the king, the clever little hun is bleeding in his bunker, you are whole again, fulﬁlled, godlike, leaning, exhausted, on your desk (your oar, your notebook, your machine) until the daemon with a thousand faces calls again – because you know he will .
'The Imitation Game'
Alan Turing is my hero, an inspiration in both my science and my art, so much that I was prepared to dislike " The Imitation Game ." Deep down, I did not expect a mere director to do him justice.
That I ended up enjoying the film is a tribute to Benedict Cumberbatch, an actor apparently specializing in brains – he is Sherlock in the BBC series, and will play Hamlet in London next August. His Turing is complex and decidedly brilliant and yet too often of one track, tragic and funny, distant and endearing. He even stutters with brio (as Alan did).
The code-breaking gang offers delightful interaction and stellar acting. It includes Jane Clarke (Keira Knightley), a young woman who is Alan's equal – or better? – in maths. They even have a brief romantic involvement. (Many viewers will assume this is a scriptwriter's liberty, to supply a few scenes of public flirt in 1940s garb, but it actually happened).
The science is appropriately scarce and almost always surprisingly well told. One exception: the war-time code-breaking computers are confused with the Turing machine. The over-dramatization of history (just-so discoveries of promethean code-breaking stratagems, non-credible coincidences, such as the brother of a member of the team happening to be on a British warship whose fate is being decided by their code breaking) is only occasional. Flashbacks to Turing's difficult adolescence in public school are superbly acted by Alex Lawther, and very moving.
Persecution of a great
The film starts with a tragic narrative, framing the wartime story: The year is now 1952, and Turing, a war hero nobody has heard of, owing to the Crown's obsession for secrecy (the Colossus was classified, its existence officially denied, until recently), tells his war story while interrogated by a police detective, after a puzzling burglary to his home.
The detective suspects espionage and another academic Soviet mole, and yet the crime uncovered by the process is of a very different kind: Homosexuality.
Turing lived his scientific life as if the clock were three or four decades ahead. He tried to live the rest of his life the same way: as the film subtly points out, he had always been less than meticulous in hiding his sexual orientation.
But tragedy loomed: one of the greatest scientists who ever lived, the father of my field and progenitor of the technology that has changed the lives of all, a brave young man who had contributed as much to his country's war victory as anybody, ended up being persecuted, fiercely and publicly, by an ungrateful nation. He was prosecuted and condemned under the Gross Indecency Act of 1885 – indeed one of the grossest among all the untold indecencies perpetrated by states.
The court offered Turing chemical castration, as a charitable alternative to prison. The hormones altered the man's body and mind. Two years later, Alan Mathison Turing died of cyanide poisoning, apparently of his own hand. He was 42.
Postscripta to the Turing story have been abundant in recent years. In 2012, a grateful world, forever transformed by the man's ingenuity, celebrated Turing's centennial. In 2013, in a statement decried by all as the epitome of too little, too late, a queen fortunate to have reigned over her victorious kingdom well into her late eighties, was kind enough to exonerate Turing through the voice of her prime minister (no mention of the 50,000 other victims of the Act).
And currently – while, by eerie coincidence, Citizenfour is playing in theaters, telling the saga of another brave young man being persecuted by the state – we have seen a thoroughly entertaining film honoring the days and ideas of Alan Turing.