Leonard Susskind: My friend Richard Feynman

904,122 views ・ 2011-05-16

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00:16
I decided when I was asked to do this
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that what I really wanted to talk about was my friend, Richard Feynman.
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I was one of the fortunate few that really did get to know him
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and enjoyed his presence.
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And I'm going to tell you about the Richard Feynman that I knew.
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I'm sure there are people here who could tell you
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about the Richard Feynman they knew,
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and it would probably be a different Richard Feynman.
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Richard Feynman was a very complex man.
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He was a man of many, many parts.
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He was, of course, foremost, a very, very, very great scientist.
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He was an actor. You saw him act.
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I also had the good fortune to be in those lectures,
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up in the balcony.
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They were fantastic.
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He was a philosopher.
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He was a drum player.
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He was a teacher par excellence.
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Richard Feynman was also a showman,
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an enormous showman.
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He was brash, irreverent.
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He was full of macho, a kind of macho one-upmanship.
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He loved intellectual battle.
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He had a gargantuan ego.
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But the man had, somehow,
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a lot of room at the bottom.
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And what I mean by that is a lot of room, in my case --
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I can't speak for anybody else, but in my case --
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a lot of room for another big ego.
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Well, not as big as his,
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but fairly big.
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I always felt good with Dick Feynman.
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It was always fun to be with him.
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He always made me feel smart.
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How can somebody like that make you feel smart?
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Somehow he did.
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He made me feel smart. He made me feel he was smart.
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He made me feel we were both smart,
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and the two of us could solve any problem whatever.
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And in fact, we did sometimes do physics together.
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We never published a paper together,
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but we did have a lot of fun.
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He loved to win,
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win these little macho games we would sometimes play.
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And he didn't only play them with me, but with all sorts of people.
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He would almost always win.
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But when he didn't win, when he lost,
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he would laugh and seem to have just as much fun
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as if he had won.
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I remember once he told me a story
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about a joke the students played on him.
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I think it was for his birthday --
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they took him for lunch
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to a sandwich place in Pasadena.
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It may still exist; I don't know.
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Celebrity sandwiches was their thing.
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You could get a Marilyn Monroe sandwich.
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You could get a Humphrey Bogart sandwich.
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The students went there in advance,
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and arranged that they'd all order Feynman sandwiches.
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One after another, they came in and ordered Feynman sandwiches.
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Feynman loved this story.
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He told me this story, and he was really happy and laughing.
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When he finished the story, I said to him,
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"Dick, I wonder what would be the difference
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between a Feynman sandwich and a Susskind sandwich."
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And without skipping a beat at all,
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he said, "Well, they'd be about the same.
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The only difference is a Susskind sandwich would have a lot more ham."
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"Ham" as in bad actor.
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(Laughter)
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Well, I happened to have been very quick that day,
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and I said, "Yeah, but a lot less baloney."
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(Laughter)
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(Applause)
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The truth of the matter
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is that a Feynman sandwich had a load of ham,
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but absolutely no baloney.
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What Feynman hated worse than anything else
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was intellectual pretense --
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phoniness,
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false sophistication, jargon.
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I remember sometime during the mid-'80s,
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Dick and I and Sidney Coleman would meet a couple of times
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up in San Francisco -- at some very rich guy's house --
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up in San Francisco for dinner.
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And the last time the rich guy invited us,
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he also invited a couple of philosophers.
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These guys were philosophers of mind.
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Their specialty was the philosophy of consciousness.
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And they were full of all kinds of jargon.
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I'm trying to remember the words --
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"monism," "dualism," categories all over the place.
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I didn't know what those meant, neither did Dick or Sydney, for that matter.
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And what did we talk about?
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Well, what do you talk about when you talk about minds?
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There's one obvious thing to talk about:
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Can a machine become a mind?
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Can you build a machine
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that thinks like a human being that is conscious?
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We sat around and talked about this -- we of course never resolved it.
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But the trouble with the philosophers
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is that they were philosophizing
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when they should have been science-ophizing.
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It's a scientific question, after all.
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And this was a very, very dangerous thing to do
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around Dick Feynman.
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(Laughter)
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Feynman let them have it -- both barrels, right between the eyes.
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It was brutal; it was funny -- ooh, it was funny.
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But it was really brutal.
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He really popped their balloon.
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But the amazing thing was -- Feynman had to leave a little early;
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he wasn't feeling too well, so he left a little bit early.
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And Sidney and I were left there with the two philosophers.
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And the amazing thing is these guys were flying.
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They were so happy.
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They had met the great man;
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they had been instructed by the great man;
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they had an enormous amount of fun
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having their faces shoved in the mud ...
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And it was something special.
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I realized there was something just extraordinary about Feynman,
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even when he did what he did.
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Dick -- he was my friend; I did call him Dick --
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Dick and I had a little bit of a rapport.
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I think it may have been a special rapport that he and I had.
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We liked each other; we liked the same kind of things.
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I also like the intellectual macho games.
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Sometimes I would win, mostly he would win,
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but we both enjoyed them.
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And Dick became convinced at some point
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that he and I had some kind of similarity of personality.
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I don't think he was right.
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I think the only point of similarity between us
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is we both like to talk about ourselves.
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But he was convinced of this.
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And the man was incredibly curious.
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And he wanted to understand what it was and why it was
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that there was this funny connection.
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And one day, we were walking.
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We were in France, in Les Houches.
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We were up in the mountains, 1976.
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And Feynman said to me, "Leonardo ..."
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The reason he called me "Leonardo" is because we were in Europe,
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and he was practicing his French.
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(Laughter)
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And he said, "Leonardo,
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were you closer to your mother or your father when you were a kid?"
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I said, "Well, my real hero was my father.
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He was a working man,
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had a fifth-grade education.
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He was a master mechanic, and he taught me how to use tools.
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He taught me all sorts of things about mechanical things.
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He even taught me the Pythagorean theorem.
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He didn't call it the hypotenuse,
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he called it the shortcut distance."
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And Feynman's eyes just opened up.
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He went off like a lightbulb.
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And he said that he had had
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basically exactly the same relationship with his father.
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In fact, he had been convinced at one time
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that to be a good physicist,
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it was very important to have had that kind of relationship
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with your father.
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I apologize for the sexist conversation here,
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but this is the way it really happened.
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He said he had been absolutely convinced that this was necessary,
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a necessary part of the growing up of a young physicist.
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Being Dick, he, of course, wanted to check this.
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He wanted to go out and do an experiment.
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(Laughter)
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Well, he did.
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He went out and did an experiment.
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He asked all his friends that he thought were good physicists,
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"Was it your mom or your pop that influenced you?"
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They were all men,
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and to a man, every single one of them said,
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"My mother."
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(Laughter)
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There went that theory, down the trash can of history.
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(Laughter)
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But he was very excited that he had finally met somebody
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who had the same experience with his father
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as he had with his father.
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And for some time, he was convinced this was the reason we got along so well.
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I don't know. Maybe. Who knows?
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But let me tell you a little bit about Feynman the physicist.
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Feynman's style -- no, "style" is not the right word.
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"Style" makes you think of the bow tie he might have worn,
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or the suit he was wearing.
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It's something much deeper than that,
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but I can't think of another word for it.
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Feynman's scientific style was always to look for the simplest,
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most elementary solution to a problem that was possible.
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If it wasn't possible, you had to use something fancier.
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No doubt, part of this was his great joy and pleasure
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in showing people that he could think more simply than they could.
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But he also deeply believed, he truly believed,
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that if you couldn't explain something simply,
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you didn't understand it.
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In the 1950s, people were trying to figure out
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how superfluid helium worked.
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There was a theory.
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It was due to a Russian mathematical physicist.
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It was a complicated theory;
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I'll tell you what it was soon enough.
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It was a terribly complicated theory,
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full of very difficult integrals and formulas
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and mathematics and so forth.
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And it sort of worked, but it didn't work very well.
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The only way it worked
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is when the helium atoms were very, very far apart.
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And unfortunately,
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the helium atoms in liquid helium are right on top of each other.
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Feynman decided, as a sort of amateur helium physicist,
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that he would try to figure it out.
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He had an idea, a very clear idea.
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He would try to figure out
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what the quantum wave function of this huge number of atoms looked like.
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He would try to visualize it,
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guided by a small number of simple principles.
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The small number of simple principles were very, very simple.
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The first one was that when helium atoms touch each other,
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they repel.
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The implication of that is that the wave function has to go to zero,
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it has to vanish when the helium atoms touch each other.
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The other fact is that in the ground state --
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the lowest energy state of a quantum system --
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the wave function is always very smooth;
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it has the minimum number of wiggles.
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So he sat down --
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and I imagine he had nothing more
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than a simple piece of paper and a pencil --
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and he tried to write down, and did write down,
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the simplest function that he could think of,
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which had the boundary conditions
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that the wave function vanish when things touch
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and is smooth in between.
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He wrote down a simple thing -- so simple, in fact,
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that I suspect a really smart high-school student
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who didn't even have calculus
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could understand what he wrote down.
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The thing was, that simple thing that he wrote down
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explained everything that was known at the time about liquid helium,
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and then some.
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I've always wondered whether the professionals --
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the real professional helium physicists --
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were just a little bit embarrassed by this.
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They had their super-powerful technique,
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and they couldn't do as well.
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Incidentally, I'll tell you what that super-powerful technique was.
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It was the technique of Feynman diagrams.
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(Laughter)
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He did it again in 1968.
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In 1968, in my own university -- I wasn't there at the time --
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they were exploring the structure of the proton.
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The proton is obviously made of a whole bunch of little particles;
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this was more or less known.
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And the way to analyze it was, of course, Feynman diagrams.
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That's what Feynman diagrams were constructed for --
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to understand particles.
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The experiments that were going on were very simple:
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you simply take the proton,
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and you hit it really sharply with an electron.
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This was the thing the Feynman diagrams were for.
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The only problem was that Feynman diagrams are complicated.
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They're difficult integrals.
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If you could do all of them, you would have a very precise theory,
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but you couldn't -- they were just too complicated.
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People were trying to do them.
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You could do a one-loop diagram. Don't worry about one loop.
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One loop, two loops -- maybe you could do a three-loop diagram,
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but beyond that, you couldn't do anything.
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Feynman said, "Forget all of that.
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Just think of the proton
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as an assemblage, a swarm, of little particles."
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He called them "partons."
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He said, "Just think of it as a swarm of partons moving real fast."
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Because they're moving real fast,
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relativity says the internal motions go very slow.
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The electron hits it suddenly --
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it's like taking a very sudden snapshot of the proton.
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What do you see?
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You see a frozen bunch of partons.
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They don't move,
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and because they don't move during the course of the experiment,
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you don't have to worry about how they're moving.
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You don't have to worry about the forces between them.
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You just get to think of it as a population of frozen partons."
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This was the key to analyzing these experiments.
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Extremely effective.
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Somebody said the word "revolution" is a bad word.
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I suppose it is, so I won't say "revolution,"
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but it certainly evolved very, very deeply our understanding of the proton,
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and of particles beyond that.
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13:58
Well, I had some more that I was going to tell you
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about my connection with Feynman,
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what he was like,
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but I see I have exactly half a minute.
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So I think I'll just finish up by saying:
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I actually don't think Feynman would have liked this event.
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I think he would have said, "I don't need this."
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But ...
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(Laughter)
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How should we honor Feynman?
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How should we really honor Feynman?
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I think the answer is we should honor Feynman
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14:26
by getting as much baloney out of our own sandwiches
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as we can.
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Thank you.
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(Applause)
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