[RADIOLAB INTRO]

ROBERT KRULWICH: Three, two, one. Hey there, I'm Robert Krulwich. Jad is on paternity leave. This is Radiolab, the podcast. And today, I thought I'd introduce you to a particular guy on a particular day in Manchester, England. It's 1952, and Alan Turing, a math professor, discovers that a number of things have disappeared from his home. Looked kinda like a burglary. He was missing a shirt, a pair of shoes.

JANNA LEVIN: An old pair of pants, maybe a compass.

DAVID LEAVITT: It was stuff. It was just household stuff. Nothing of any value.

JANNA LEVIN: Nothing of any value.

ROBERT: That's Janna Levin and David Leavitt. Both of them have written books about Alan Turing.

DAVID LEAVITT: And so being very literal-minded, he thought, "Well, what do you do when you're robbed? You call the police."

JANNA LEVIN: So the police come to his house, the detectives. He has this conversation, and they say, "You know, he's kind of a curious chap." They let him talk, and they're like, "It's a real shame we're going to have to arrest him."

ROBERT: Who?

JANNA LEVIN: Turing.

ROBERT: Why would they have to—they're just coming to ...

JANNA LEVIN: Because he's effectively implicated himself in terms ...

ROBERT: Here's what happened. The police sat Turing down and said, "Who do you think made off with those things of yours?" And he says to them ...

DAVID LEAVITT: He suspected the thief was an acquaintance of his boyfriend.

ROBERT: His boyfriend.

DAVID LEAVITT: Yes. Yes.

ROBERT: You see, at the time, there was a law in England ...

DAVID LEAVITT: Which criminalized, quote-unquote, "Acts of gross indecency between adult men in public or private."

ROBERT: So he told the cops that he was having sex with a guy, is that why ...

JANNA LEVIN: He doesn't exactly say we're having sex. But he says enough that it's clear.

ROBERT: Oh.

JANNA LEVIN: He was never ashamed of being gay. This was just not something, again, that he understood what the fuss was about.

ROBERT: So what happened to him? Was he convicted?

JANNA LEVIN: Yeah. He's convicted and he's ...

ROBERT: What's his sentence?

JANNA LEVIN: Estrogen pills and implants. Estrogen implants.

ROBERT: Oh my God!

JANNA LEVIN: Yeah. Chemical castration.

ROBERT: And when I learned this, I wondered if those policemen had any idea that the guy they were arresting was, first of all, one of the great minds of the 20th century, a war hero who single-handedly, almost by himself, shortened World War II by at least two years. And the questions he posed way back then are still, I think, the most provocative ideas I know. But we're getting a little ahead of ourselves, so let me back up to when he was a schoolboy around 15 or 16 in England.

DAVID LEAVITT: He gets to Sherborne School, which is the public school, as they say in England.

JANNA LEVIN: I guess you would call it a boarding school, boarding school for boys, where ...

ROBERT: What did he look like?

JANNA LEVIN: He had dark hair, very dark hair. Sort of square face. He wasn't unattractive, he was just so goofy.

ROBERT: So did the other kids make fun of him at school, or did he ...?

JANNA LEVIN: Yeah. I mean, he's teased, taunted, bullied, but he's not completely unhappy. He falls in love.

DAVID LEAVITT: With another student named Christopher Morcom.

JANNA LEVIN: He was very charming, very socially smooth, handsome. And they have this bond over science. It's an unrequited love.

ROBERT: Did he express his love to this other kid, or ...?

JANNA LEVIN: I think it was pretty obvious. He was always sort of there, standing next to Chris Morcom, every class, right behind him, right next to him. And I think at some point Chris commented that, you know, "Maybe it's a little too much attention." But I don't think he really made a formal declaration of his love. But he did maintain a relationship with Chris' mother, even after Chris died. Chris Morcom died while he was still in school of Bavarian tuberculosis.

ROBERT: Huh.

JANNA LEVIN: And had kept his illness a secret. Just one day, there was just this announcement he was dead. So I think it came as a complete shock to Alan.

DAVID LEAVITT: His memory really lingered, and I think that ...

ROBERT: How do we know that a kid had a boy crush in school?

DAVID LEAVITT: There are letters. Most moving are the letters that he wrote after Morcom's death.

ROBERT: We actually went out and found a few of them, and here's one that he wrote to his mother. He says, "I feel sure that I shall meet Morcom again somewhere, and there will be some work for us to do together, as I believe there was for us to do here. Now that I'm left ..."

JANNA LEVIN: He wanted to believe that Chris's spirit lived on, and he was sort of awkwardly trying on these ideas that he had inherited from his religious upbringing. And ...

ROBERT: But—and you can see this in the letters too ...

JANNA LEVIN: Turing begins to lose his faith, and eventually comes to this sort of brutal conclusion that when Chris was gone he was gone."

ROBERT: The only love he had left at that point was mathematics. So he goes off to King's College, Cambridge to study math.

DAVID LEAVITT: Yeah, exactly.

ROBERT: He was still kind of a loner.

DAVID LEAVITT: If you look at photographs of Turing, I think I'm always struck by the fact that he looks like he's not actually there. He looks like he's—like a lot of mathematicians, he lives simultaneously in two different worlds—the world that the rest of us live in, and a world lived in a kind of extraordinary world of abstraction.

JANNA LEVIN: You know, lying in the fields in Cambridge, just him and his thoughts.

ROBERT: Hmm. Staring up at the sky?

JANNA LEVIN: [laughs]

ROBERT: Or was that just ...

JANNA LEVIN: He did do that. He would literally go and lie in the meadow, and he would have these epiphanies, these realizations.

ROBERT: And one day, he's lying in Grantchester Meadows—that's near the campus—and he's thinking over a pretty tough problem: is there a quick, automatic way to prove or disprove a mathematical proposition. This was a big question in math at the time. The ins and outs of which aren't all that important to us, what's important is that it led to Alan Turing's idea for, of all things, a machine.

JAMES GLEICK: The machine doesn't exist. The machine is never built. It is never meant to be built.

ROBERT: This is James Gleick, a science writer who has studied Turing.

JAMES GLEICK: It's the world's most impractical machine.

ROBERT: But it's very simple.

JAMES GLEICK: These were the elements of the machine.

ROBERT: Number one ...

JAMES GLEICK: Piece of tape infinitely long, so therefore it's already never gonna exist, because we can't have infinitely long pieces of tape. And ...

ROBERT: Number two, something that reads or writes ones and zeros on the tape. And number three, a set of instructions.

JAMES GLEICK: So if you've got a zero, then you go to the left and you write a one. Or if you've got a one, go to the left and you write another one. And you've gotta remember where you've been, so you have a certain amount of memory, but that's it. And then he proved that the machine could do anything.

ROBERT: You could add, of course, and then you could subtract and multiply. You could also do a little calculus—actually a lot of calculus. You could do trig and mathematical proofs and sophisticated mathematical proofs.

JAMES GLEICK: Anything that could be done in mathematics mechanically could be done by his imaginary, idiot, simple machine.

ROBERT: Is this such a big idea? I mean, all you're saying really, is he figured out how to put logic, or actually how to program a machine.

JAMES GLEICK: [laughs] Okay. But no, Robert, you're already cheating because as soon as you say you're gonna give the machine some logic ...

ROBERT: Yeah?

JAMES GLEICK: ... and then as soon as you use the word "program," you're using very modern bits of knowledge that we've all internalized. But the idea of putting logic into a machine, no one thought of that. That's just weird!

DAVID LEAVITT: Machines at that time, bear in mind, were generally single function.

JANNA LEVIN: The idea that you do your email on your computer and Photoshop, you know, you don't buy a different machine. That is ingenious. That traces back to Turing's original idea, that I can build an electromechanical brain and I can teach it how to do different things.

ROBERT: This was the dawn of the computer age.

JANNA LEVIN: "Computer" used to mean a person.

DAVID LEAVITT: Usually a woman who would sit and do mathematics.

ROBERT: And now we got this guy who's saying that with a simple formula—tape, code and a set of instructions—we can give human-like abilities to a machine. And not just the abilities of our hands, but the nimble ability of our beautiful brains.

JAMES GLEICK: It's a beautiful, magical, simple idea. Turing's machine is Cézanne's watercolors, it's—it's Bach's Prelude. He was a lonely 22 year old just thinking, and he invented a thing that lives in the minds of every computer scientist today. He didn't realize that just a few years later he was gonna be applying these same skills to winning the war for—for England.

[NEWS CLIP: The Battle of London, which began with strong forces of Nazi bombers attacking the capital at night, led to a big fire on the waterside early in the ...]

ROBERT: It's 1940, and the German high command is sending secret messages written in code to naval commanders, to U-Boat captains, saying, like, "Sink that ship, mine this harbor." The messages were encrypted in this crazy-fangled encrypting thing that they called the Enigma Machine.

JANNA LEVIN: Kind of a typewriter. So ...

ROBERT: They would type, "Bomb that boat"—in German, of course—and the machine would swap the letters and turn the type into gibberish.

JANNA LEVIN: But they changed the settings every transmission, and what this meant was that it was considered by both the Germans and the British to be uncrackable.

ROBERT: Except Winston Churchill thought, "Let me try." So in total secrecy, British Intelligence brought together the most talented amateur decoders that they could find.

DAVID LEAVITT: They chose mathematicians.

JANNA LEVIN: Chess champions.

DAVID LEAVITT: People who could solve the Sunday Times crossword puzzle extremely fast.

ROBERT: And they were all instructed to go to a set of buildings halfway between Oxford and Cambridge. It was a place called Bletchley Park.

DAVID LEAVITT: But the architect of the effort, really, was Alan Turing.

ROBERT: Who was an odd kind of choice because in many ways he was a very strange man.

DAVID LEAVITT: He was kind of paranoid. I think that was clear. I mean, he had this system where his bicycle chain came off every certain number of revolutions, and he knew how many revolutions he was able to ride before the chain would come off.

ROBERT: [laughs]

DAVID LEAVITT: And it was, I think, in order to stop other people from riding his bicycle. But he was the one who again had a very typically Turing-ish sort of breakthrough. He thought, "Well, this code is generated by a machine, therefore a machine can be built that will be able to break the code." So he built this machine that was called The Bomb. And it was ...

ROBERT: And it was huge. It was the size of a wall, and it could try out all kinds of different solutions to this breaking the code problem. And Turing decided to focus this machine on one little Achilles heel that he found in the code itself. At the beginning of a typical message, a German would get on the machine, and he'd have ...

JANNA LEVIN: Sort of habitual openings.

DAVID LEAVITT: You know, phrases that were very, very commonly used. And the Germans were fairly unimaginative.

ROBERT: Unimaginative at the start, like, you know, "Heil Hitler!" Or, "Good morning!"

DAVID LEAVITT: Yeah.

ROBERT: Or something like that.

DAVID LEAVITT: Exactly.

JANNA LEVIN: Heil Hitler, or the weather, or ...

ROBERT: So "Heil" would be H-E-I-L.

JANNA LEVIN: Right, yeah.

ROBERT: There's your in.

JANNA LEVIN: And then they realized that they could actually crack the code because of this, I would say, misstep.

[NEWS CLIP: Throughout the world, throngs of people hail the end of the war in Europe!]

ROBERT: When the English realized that Alan Turing and his team had broken the code, did that make Alan Turing into a superstar? I mean, did he get, like, a birthday greetings from the Queen?

DAVID LEAVITT: No, not at all. Because it was all top secret.

ROBERT: Well, does that mean that King George didn't know of Alan Turing, or Winston Churchill didn't know of ...

DAVID LEAVITT: Churchill certainly knew.

JANNA LEVIN: Churchill definitely took a particular interest in Turing and Turing's transmissions.

ROBERT: Oh, he did?

JANNA LEVIN: Sure.

ROBERT: Oh!

JANNA LEVIN: No, he's a war hero. There's no question about that. His contribution is of crucial importance in terms of turning the tide of the war in favor of the Allies.

ROBERT: And yet ...

JAMES GLEICK: As far as I'm aware, Turing was never thanked or acknowledged for what he did.

ROBERT: Well if I were King George, I would have, like, sent him a little, um ...

JAMES GLEICK: He didn't.

ROBERT: Having defeated the Enigma Machine, Turing now goes back to his first love: the Turing Machine. Mathematicians all over the world are now building computers and big, refrigerator-sized contraptions, actually. There was one at Manchester University, where Turing took a teaching job. And the one there did a lot more than just math.

JAMES GLEICK: And the machine could do all sorts of things. I believe it could sing.

ROBERT: [laughs]

JAMES GLEICK: I'm pretty sure it could sing "God Save the King."

ROBERT: Really?

JAMES GLEICK: Not very well.

ROBERT: This is what it actually sounded like. It's not something you'd really want to march to.

JAMES GLEICK: It was not the machine that Turing ideally would have liked to build.

ROBERT: Turing had a bigger idea at this point.

JAMES GLEICK: The idea of the thinking machine. He really invented the field of artificial intelligence, and was the first person to hypothesize about whether a machine could actually be said to think.

ROBERT: And not just think, thought Turing, but maybe flirt with you a little bit, or joke with you. To have a sentience inside an electronic, manufactured mind.

JANNA LEVIN: And when people said, "How would you know that mind was truly sentient?" He said, "Just ask it. Just ask it"

JAD ABUMRAD: "Are you truly sentient?"

[COMPUTER VOICE: Yes.]

ROBERT: [laughs] Well, it's not gonna be ever that easy, but Turing did come up with a test, a way to test whether a machine is doing something like thinking, like human thinking.

JAMES GLEICK: What we now call the Turing test.

ROBERT: We've described it on our show before.

JAD: How we'll know is ...

ROBERT: This from a show we called "Talking to Machines."

JAD: Get a person, sit them down at a computer, have them start a conversation in text.

BRIAN CHRISTIAN: You know, "Hi, how are you?" Enter. "Good" pops up on the screen.

JAD: Sort of like internet chat.

ROBERT: Yeah.

JAD: So after that first conversation, have him do it again and then again. You know, "Hi. Hello. How are you?" Et cetera.

BRIAN CHRISTIAN: Back and forth.

JAD: But here's the catch ...

BRIAN CHRISTIAN: Half of these conversations will be with real people, half will be with these computer programs that are basically impersonating people.

JANNA LEVIN: If you can put this thing behind a curtain, and you talk to it and it convinces you that it's intelligent and alive and sentient, then it is. What's the big fuss?

ROBERT: But there was a big fuss.

JAMES GLEICK: One second.

ROBERT: A neuroscientist at the time, Sir Jeffrey Jefferson, turned to Turing and said, "How dare you! No machine will ever think like a human, because no machine can feel like we do in all the ways we do."

DAVID LEAVITT: "Pleasure at its success, grief when its valves fuse, be warmed by flattery, be made miserable by its mistakes, be charmed by sex, be angry or miserable when it cannot get what it wants."

ROBERT: Huh.

DAVID LEAVITT: And Turing's response to that was, "Well, I can say the same thing to you." You know, I can say to you, Robert, "I don't know what's going on inside your brain. You tell me what you're feeling and what you're experiencing, but how do I know that what you're—how do any of us know that any other human being is a human being?"

JANNA LEVIN: Turing is really one of the first to say—he's the first to say, "It's not just that I want to build a machine that can think, it's that we are machines that think."

DAVID LEAVITT: We are nothing more than flesh, blood, neurons. We are just machines ourselves.

JANNA LEVIN: Just soulless, biological machines. And this isn't a dark moment for him.

ROBERT: It's a moment of acceptance, says Janna. But this time, it's not about math or science, it's about something bigger. It's about the nature of the universe and our place in it. And according to David, not only did Turing feel like he himself was kind of a machine, he felt a kinship with all the thinking machines that would ever be manufactured in the future. All those mechanical minds. He felt he had something in common with them.

DAVID LEAVITT: For Turing, the machines were more likely to be victims—victims of prejudice, victims of injustice, victims of people like Jefferson. Jefferson is saying to the machines, "You don't think because I say you don't think." And, you know, England was saying to Turing, "You can't be what you are, and we're going to change you."

ROBERT: Which brings us back to where we started this show. It is now 1952. Alan Turing has been convicted of gross indecency, a crime punishable by, as we told you, a jail term or the court can order you to take hormone injections.

DAVID LEAVITT: And he was given a choice. He could go to prison or he could be, quote-unquote, "cured." And the cure consisted of massive doses of estrogen.

ROBERT: Nobody important went and said to the judge, "Here's a character reference."

DAVID LEAVITT: No.

ROBERT: "By the way, this guy won the World War that we just fought." Or ...

DAVID LEAVITT: Well, I suppose you could say that they were cutting him a break by not sending him to prison, by giving this horrific, horrific alternative.

ROBERT: What were the hormones supposed to do?

DAVID LEAVITT: It was the crudest kind of pseudoscience. There was some claptrap theory that homosexuality could be cured through injections of estrogen. What it really did was it made him ...

JANNA LEVIN: Impotent and profoundly depressed. He grows breasts. This certainly doesn't work to repress his homosexuality. He's still vocally gay.

ROBERT: But he's also worried that because he's now famously gay, his court case being in the papers and all, that everybody from now on will dismiss his ideas. Writing once to a friend, he said ...

DAVID LEAVITT: "I'm rather afraid that the following syllogism may be used by some in the future. Turing believes machines think. Turing lies with men. Therefore, machines do not think." It is signed, "Yours in distress, Alan."

ROBERT: The hormone treatments ended. He kept working, but his mood darkened.

DAVID LEAVITT: Turing's favorite film was Snow White and the Seven Dwarves. And he particularly loved the scene where the—the witch dips the apple in the brew and she chants, "Dip the apple in the brew, let the sleeping death seep through."

ROBERT: One night in 1954, it was June 8, he was at home, and at some point during that night ...

JANNA LEVIN: He kills himself.

ROBERT: How?

JANNA LEVIN: He laces an apple with cyanide and he bites from the poison apple.

ROBERT: He left no note. 55 years later, in 2009, the Prime Minister of Great Britain, Gordon Brown, issued a formal apology to Alan Turing. And in 2011, coming up on his hundredth birthday, 23, 000 people sent a petition to the British government asking that Alan Turing be given a posthumous pardon for the so-called crime of "moral turpitude." In 2012, a government minister, Lord Tom McNally, said, "No, that we will not do." Here's the statement.

ROBERT: "A posthumous pardon was not considered appropriate, as Alan Turing was properly convicted of what was at the time a criminal offense. He would have known that his offense was against the law and that he would be prosecuted."

ROBERT: It's an amazing life, and I'm in awe that anybody could have accomplished quite as much as he did—and suffered as much as he did. It's almost overwhelming. But when I think about it, there's a piece of what Alan Turing thought up that just hurts a little—at least me. This idea that machines can one day become, in fact, our equivalent.

JAMES GLEICK: This is still just such a powerful and emotional question for us to deal with. And I guess we're still divided between people who think that would be kind of a cool thing and people who think that would be a horrible thing. And the people who think it would be a horrible thing, I guess feel that way partly because it makes us feel kind of bad about ourselves. You know, because we aren't—there's nothing magical about us if we're just machines. But ...

ROBERT: Do you fall on—do you fall on one side of these lines?

JAMES GLEICK: No. I think—what I'm willing to say is I think we're just machines. And ...

ROBERT: Huh.

JAMES GLEICK: ... I think we're just made of matter. I'm sorry to be giving religious opinions here, because these are religious opinions, but for me, that doesn't make me feel that we're any less special. That makes—I think how—what a wonderful thing, that a collection of matter created by a process of evolution that lasted billions of years, how wonderful that this process and that these little collections of matter are able to produce Cézanne's watercolors and Bach's Preludes.

ROBERT: But ...

JAMES GLEICK: I can live with that.

ROBERT: ... could you—if I built you a computer that could create equally beautiful watercolors and equally beautiful musical compositions, would you feel happier, or diminished?

JAMES GLEICK: I think in a way, you're asking if you see how the trick is done, does it then vanish? Does it just become a trick? The trick being a great painting or a great piece of music. I feel the art I love is always art that I don't fully understand. There's some mystery there always. I don't quite fathom it. Now so if the computer is churning out a bunch of notes and you know exactly what the rules are that the computer is following and there's no mystery, how can that possibly be a great piece of music? And the answer is we don't know how the computer is gonna do it. We don't know how the machine is gonna do it, and when the machine produces music that is as lovely as the music that you and I love, I believe it will still be unfathomable.

ROBERT: James Gleick is the author of The Information. It's a book about information theory and artificial intelligence. David Leavitt has a book called The Man Who Knew Too Much. It's a biography of Alan Turing. And Janna Levin has a novel about Turing and Kurt Gödel, another mathematician, she calls her novel—and it's quite something, too, actually, it's kinda like a—well anyways, it's called A Madman Dreams of Turing Machines. Jad will be back soon. I'm Robert Krulwich. This is Radiolab.

[LISTENERS: Hey Radiolab, this is Billy Davenport. And Mila Davenport. We're listeners from Knoxville, Tennessee. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.org. Thank you, Radiolab!]

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