大象传媒

Discovery: The Feynman Variations 大象传媒 World Service

Original broadcast 29 September 2010

Transcript

Copyright 大象传媒

Presenter: Brian Cox

Producer: Rami Tzabar 听听

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颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅颅

Set to Bongos playing (note 鈥� this is a recording of someone playing Feynman鈥檚 actual bongos!)

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FEYNMAN ON UNCERTAINTY

I have approximate answers and possible beliefs and different degrees of certainty about different things, but I'm not absolutely sure of anything and there are many things I don't know anything about, such as whether it means anything to ask why we're here, and what the question might mean.

I might think about it a little bit and if I can't figure it out, then I go on to something else, but I don't have to know an answer, I don't feel frightened by not knowing things, by being lost in a mysterious Universe without having any purpose, which is the way it really is so far as I can tell. It doesn't frighten me.

0.33 (from Horizon: the pleasure of finding things out)

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MESSENGER LECTURE 1 CLIP (INTRODUCTION by provost of Cornell)

Ladies and Gentlemen .. it鈥檚 my privilege to introduce the Messenger Lecturer Mr Richard P Feynman of CALTECH. Professor Feynman is a distinguished theoretical physicist and he鈥檚 done much to bring order out of the confusion which has marked much of the spectacular development in physics during the post war period. Before I let him talk I want to tell you just a little bit more about him. 3-4 years ago he started teaching a beginning physics course at Caltech and the result has added a new dimension to his fame. His lectures are now published in two volumes and they represent a refreshing approach to the subject. In the preface to the published lectures there is a photograph of Feynman (laughter) performing happily on the bongo drums (laughter)鈥� Another of his specialities is safe cracking (laughter) one legend says he once opened a locked safe in a secret establishment, removed a secret document and left a note that said 鈥榞uess who?鈥� I could tell you about the time that he learned Spanish before he went to give a series of lectures in <?xml:namespace prefix = "st1" ns = "urn:schemas-microsoft-com:office:smarttags" />Brazil, but I won鈥檛 (huge laughter) FADES鈥�

1.16

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BRIAN COMM

Richard P Feynman was one of the most important and influential scientists of the second half of the 20th century, arguably as influential as Einstein. He was possessed with a remarkable ability not only to understand the inner workings of the natural world but also an innate talent at communicating them to the rest of us. As curious as he was clever, Feynman not only made great contributions to physics, but also to other branches of science.

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And yet many people have probably never heard of him, but to physicists he is something of a legend, as Nobel Laureate Hans Bethe and Feynman鈥檚 mentor during his early career, recalls

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BETHE

Feynman was a Magician. With an ordinary genius 鈥μ� well he does very good work and it鈥檚 not easy to do this kind of work but you can imagine if you try very hard you could do similar work and get to a similar answer but with a magician you just don鈥檛 know how he does it.

0.25

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FEYNMAN Messenger Lecture 听7: New Laws

In general we look for a new law by the following process鈥�first we guess it [laughter], don鈥檛 laugh that鈥檚 really true. Then we compute the consequences of the guess to see if this is right if this law that we guessed is right and then we compare those results to nature or to experiment or experience with direct observation to see if it works鈥�If it disagrees with experiment鈥� it鈥檚 WRONG. In that simple statement is the key to science. doesn鈥檛 make any difference how beautiful your guess 鈥�or how smart you are, who made the guess or what his name is, if it disagrees with experiment, its wrong, that鈥檚 all there is to it 鈥�[giggling]鈥�

0.44

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FADE UNDER

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BRIAN

Feynman was in the vanguard of his profession but he never seemed elitist. He was seen as eccentric and awkward, an image he enjoyed playing up to, with a healthy disregard for authority. And for the most part he enjoyed playing the gallery. 听Today, we鈥檙e more used seeing scientists in the media, presenting programmes, authoring populist books.听 But back then, this was rare and Feynman鈥檚 great skill as a scientist was matched by his remarkably deft ability to communicate ideas to students and public alike with incredible clarity and wit. No wonder he was dubbed 鈥淭he Great Explainer鈥�. 听Though when asked by a reporter to explain what he got the Nobel for, in 3 minutes, he famously quipped, 鈥渋f I had to explain it in 3 minutes it wouldn鈥檛 be worth a Nobel prize鈥濃��

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WEINBERG

Richard Feynman was a participant in one of the greatest scientific breakthroughs of the 20th century or indeed any century, the development right after WW2 of听 an understanding of the interactions of light and charged particles that鈥檚 known as quantum electro dynamics

0.20

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BRIAN

Steven Weinberg, another Nobel winning physicist, on the theory that made Feynman famous, at least in science. Quantum Electro Dynamics or QED 鈥� it鈥檚 basically an explanation for all phenomena that鈥檚 important in the everyday world, everything from how atoms give out light to why the ground beneath your feet is solid and it鈥檚 the most successful theory ever devised by human beings. Its predictions agree to many, many decimal places and there is nowhere (so far that we know) where it doesn鈥檛 actually match experiments.

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Feynman shared his Nobel with two other physicists who made key contributions to QED - Sin鈥揑tiro Tomonaga from Japan and fellow American Julian Schwinger. As Steven Weinberg explains, Feynman鈥檚 contribution was and remains unique, something that they believe no one else could have come up with 鈥� they鈥檙e called Feynman Diagrams鈥�

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WEINBERG

Feynman has his characteristically innovative and personal approach that was eventually expressed as Feynman Diagrams 鈥� a unique language 鈥� that now all physicists that work on elementary particles use to communicate with each other鈥�to express what physical effects 鈥� what calculation they鈥檙e doing 鈥�

This was a Feynman contribution that has proved to be of inestimable value to physics鈥�

0.35

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BETHE

It never occurred to any of us to put the calculations so graphically and then to combine the electrons and positrons in this ingenious way, that鈥檚 just why he is a genius

0.19 (NOG 1)

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BRIAN

The idea of turning the complexities of sub-atomic behaviour from abstract mathematics to two dimensional drawings 鈥� doodles almost 鈥� was such a startlingly simple idea, almost childlike, yet obvious to no one else but Feynman.

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WEINBERG

Students used to come over from Harvard to take my course in QED and it wasn鈥檛 because I was a brilliant lecturer it was because I used Feynman Diagrams鈥� distinguished Professor from Harvard, Julian Schwinger didn鈥檛 like Feynman Diagrams and he wouldn鈥檛 use them but the students knew they had to learn this language鈥�

0.29

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BRIAN

Steve Weinberg. One student during Feynman鈥檚 early days at Caltech was Ronald Blum, having just graduated with his friend Carl Sagan, back in Chicago, he arrived in California in 1956 to study physics and encountered Feynman, whose reputation for extra-curricular activities was almost as great as his reputation for science.

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BLUM

At Caltech Feynman was the golden boy. He was everybody鈥檚 ideal physicist, in other words if you had to be a physicist鈥� you鈥檇 want to be Feynman, a guy like Einstein, a bit inaccessible, looked strange, Feynman look and talked like a regular guy, he was resolutely egalitarian and opposed to pretence of any kind and yet he played bongos, had a sense of humour 鈥�

0.32

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FEYNMAN Messenger Lecture: gravitation 鈥� sound quality!!

Now鈥�that shows that gravitation extends to the great distances鈥�but Newton said that everything attracted everything else鈥�do I attract you 鈥� excuse me I mean 鈥榙o I attract you?鈥� I was gonna say do I attract you physically鈥�[laughter]

0.19

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FADES

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BLUM

鈥�I guess it was Julian Schwinger who called Feynman the greatest intuitionist of the 20th century, a man for whom physics reasoning was so reflexive and on the right track that I guess to me he always seemed like the Mozart of physics 鈥� this was what he did

0.18

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HIBBS

One on One with me as a student he was very good. In lectures, in advance lecture courses he was inspiring.

0.05

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BRIAN

Al Hibbs was one of Feynman few PhD students and understood that Feynman鈥檚 unique performances, entertaining as they were, could also be counter-productive at times.

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HIBBS

鈥� there was a saying that a lecture from Feynman was like a Chinese Meal, an hour later you wonder what you learned. Because he was talking, this was common, many had this experience, while he was speaking everything quite clear, carried you along with his stream of thought, from one idea to the other to the conclusion but an hour later when you tried to reconstruct the stream of thought you couldn鈥檛 you lost some of the key elements, that seemed so obvious when he was talking鈥�but his way of thinking was not typical

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FEYNMAN Horizon: Pleasure of Finding things out: 鈥楩lower鈥�

I have a friend who's an artist, and he sometimes taken a view which I don't agree with. He'll hold up a flower and say, "Look how beautiful it is," and I'll agree. But then he'll say, "I, as an artist, can see how beautiful a flower is. But you, as a scientist, take it all apart and it becomes dull." I think he's kind of nutty. First of all the beauty that he sees is available to other people and to me too although I may not be quite as refined aesthetically as he is, I can appreciate the beauty of a flower. At the same time, I see much more about the flower than he sees, I could imagine the cells in there the complicated actions which also have a beauty, not just beauty at this dimension, 1 cm there鈥檚 also beauty at smaller dimensions, the inner structure. Also the processes, the fact that the colour of the flower evolved to attract insects, in interesting it means they can see the colour 鈥� it asks another question 鈥� does this aesthetic sense have evolved in lower forms? There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower. It only adds. I don't understand how it subtracts.

1.27

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BRIAN

Feynman鈥檚 unique way of thinking was something many of his students would be deeply affected by, even decades later. But for the rest of us, the Feynman affect would have to wait until a landmark documentary turned up on 大象传媒2 way back in 1981, called The Pleasure of Finding Things Out. It was the start of long relationship with filmmaker Christopher Sykes鈥�

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SYKES

I was somewhat intimidated by Feynman鈥檚 reputation鈥�.I knew he was a Nobel laureate and also a scary sort of character intellectually鈥�anyway I rang him up and he didn鈥檛 like the idea of a television programme at all, he said he didn鈥檛 really like that sort of thing but I told a lie and said I was going to LA anyway and asked if it would be possible to come and see him鈥�.actually I didn鈥檛 know I was going to tell you this story but I will because it鈥檚 quite funny鈥�and he said well, I lecture between 11-12 each day and if you come along I could see you just after the lecture at 12. So I went to LA, I thought I鈥檇 go to the lecture, there were about 8 guys in there and they were all Chinese and they all had shorts and trainers on and no-one took notes and Feynman was giving a lecture in some aspect of quantum theory 鈥� totally incomprehensible to me, but there was one really good thing which was just at the end he stopped and looked at the clock and he said 鈥榥ow this problem we鈥檝e been talking about there are two ways of dealing with it. One is very messy and complicated and the other is just beautifully simple and we鈥檝e only got five minutes so I鈥檒l just tell you about the messy and complicated one鈥�.

1.13

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FEYNMAN PLEASURE 鈥� Honours

I don鈥檛 like honours. I鈥檓 appreciated for the work that I did and I notice that other physicists use my work I don鈥檛 need anything else, there鈥檚 no sense in anything else, I don鈥檛 see that it makes any point that someone in the Swedish academy decides that this work is Nobel enough to receive a prize, I鈥檝e already got the prize, the prize is the pleasure of finding the thing out, the kick of the discovery the observation that other people use it those are the real things, the honours are unreal to me. I don鈥檛 believe in honours.

0.41

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SYKES

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SYKES

It鈥檚 become a cult film and sometimes I get letters from professors of physics at Bermuda or Barbados or Wisconsin or somewhere and it鈥檚 all because I watched this film, when I was twelve or thirteen, this Horizon, the pleasure of finding things out 鈥�

0.21

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FEYNMAN PLEASURE 鈥� (encyclopaedia)

We had the Encyclopaedia Britannica at home and even when I was a small boy he used to sit me on his lap and read to me from the Encyclopaedia Britannica, and we would read, say, about dinosaurs and maybe it would be talking about the brontosaurus or something, or the tyrannosaurus rex, and it would say something like, "This thing is twenty five feet high and the head is six feet across," you see, and so he'd stop all this and say, "Let's see what that means. That would mean that if he stood in our front yard he would be high enough to put his head through the window but not quite because the head is a little bit too wide and it would break the window as it came by. Everything we'd read would be translated as best we could into some reality and so I learned to do that - everything that I read I try to figure out what it really means, what it's really saying鈥�

0.58

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BRIAN

What鈥檚 driving Feynman in these films is endless fascination with the nature of things and this would be the sole focus of his next TV project with Sykes, called Fun to Imagine

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FEYNMAN Fun: intro

The world is a dynamic mess of jiggling things if you look at it right and magnified you can hardly see anything anymore because everything is jiggling and all in patterns and all lots of little balls 鈥� its; lucky that we have such a large scale view of everything so that we can see them as things without having to worry about these little atoms all of the time

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BRIAN 鈥� a guide

Fun to Imagine, broadcast in 1983, was a series of 6 shorts, in which Feynman explains the laws behind everyday phenomena such as why things feel hot or cold, how do mirrors work, how light works, using vivid stories, analogies and explanations dramatically enhanced through his intricate hand movements. But in one scene, there鈥檚 a memorable exchange between Feynman and Sykes, who鈥檚 asking the questions off-camera, which reveals what some have called a key flaw in Feynman鈥檚 thinking about how to communicate ideas. But others suggest this is an example of Feynman鈥檚 intellectual honesty 鈥� his refusal to 鈥榗heat鈥�. It concerns just how much one can simplify a complex scientific ideas and it still make sense? For once it seemed, the 鈥楪reat Explainer鈥� was stumped鈥�Sykes starts off asking him about magnetism鈥�

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FUN MAGNETS (argument)

CS: If you get hold of two magnets and you push them and feel this pushing, what is this feeling?鈥�RPF: what do you mean what鈥檚 the feeling? CS: Well it鈥檚 a sensation that something is there when you push these 2 magnets together鈥�RPF: listen to my question, what do you mean when you say there is a feeling, of course you feel it but what do you want to know? CS: What I want to know is what鈥檚 going on鈥�RPF: they repel each other鈥�CS: yes but what does that mean, or why are they doing that or how?听 [long silence]鈥�CS: I have to say that this is a perfectly reasonable question 鈥�RPF: 听Of course, it鈥檚 an excellent question okay? But the problem is when you ask FADE

0.58

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FADE UNDER CHRIS

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SYKES

I realise now listening to it鈥�I asked 5-6 questions, I didn鈥檛 realise what I was asking鈥�about was one of the most difficult problems in the whole of physics to which he knows the answer as well as anybody but he took care to explain in a very interesting way why he wasn鈥檛 going to be able to answer the question that I鈥檇 put鈥�

0.37

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FADES UP

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FEYNMAN Fun: Magnets 鈥� CUT for now

鈥�For example鈥�if we said the magnets would be connected together as if they were attached by rubber bands I would be cheating you 鈥� I鈥檒l get into trouble because you鈥檒l ask me about the nature of the bands and secondly if you were curious enough you鈥檇 ask me more questions about the rubber bands and I鈥檇 ended up explaining that and I would have cheated you very badly you see but I really can鈥檛 do a good job of explaining magnetic force in terms of something else that you鈥檙e more familiar with because I don鈥檛 understand it in terms of anything else you鈥檙e more familiar with

0.45 CUT for now

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BRIAN

For me, this argument between physicist and television producer provides an insight into why Feynman was such a brilliant scientist. He is not being difficult for the sake of it 鈥� he simply is not comfortable offering an explanation of something if it must be incomplete and therefore not illuminating. Many scientists, I assume, because I do it, try to explain things to themselves in their heads as part of the process of developing a deep understanding. The best scientists will not trick themselves or gloss over the details 鈥� they want to leave no gaps in their understanding. What you hear in this wonderful clip is this internal scientific integrity extended to the popularisation of science 鈥� and it is a valuable lesson. An explanation of something which is made so simple that it is wrong and without content, never helped anyone to understand anything.

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FADES

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FEYNMAN

If you鈥檙e interested in the ultimate character of the physical world and at the present time our only way to understand that is through mathematical reasoning then I don鈥檛 think a person can fully appreciate or much of these aspect of the world in great depth or character of the universality of the laws the relationships of things without an understanding of mathematics I don鈥檛 know any other way to do it we don鈥檛 know any other way to describe it accurately and well or to see the interrelationships without it so I don鈥檛 think a person who hasn鈥檛 developed a mathematical sense is capable of fully appreciating this aspect of the world DON鈥橳 misunderstand me there are many aspects of the world mathematics is unnecessary for such as LOVE and which are very delightful and wonderful to appreciate and to be awed and mysterious about and I don鈥檛 mean to say that the only thing in the world is physics but if that鈥檚 what you鈥檙e talking about then to no know mathematics is a severe limitation in understanding the world

1.14

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WEINBERG 鈥� very important point being made here

鈥� one of the truly interesting questions in the philosophy of science is what is a physicist doing when he uses mathematics and I think they way Feynman expressed it is right, that mathematics is not only a logical engine to draw conclusions from theories, that we use for example to take the theory and then calculate the energy or scattering probability, but it is also the language in which indispensably our theories are expressed 鈥� we cannot state our theories without mathematics. Of course this is the great tragedy of physics that we think we鈥檙e making great progress, I think so, but we can鈥檛 ever succeed in explaining to the public just what we鈥檙e doing without mathematics which is not generally known by people.

0.58

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BRIAN

Weinberg and Feynman are of course correct 鈥搕he true beauty and power of physics is made manifest in the language of mathematics. This is perhaps where much of the disconnect between the scientific world-view and some members of the non-scientifically trained public lies. It is, as Weinberg says, a tragedy. Imagine if a deep appreciation of music, literature or art were only accessible after years of study of an entirely new and difficult language.

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The challenge for those wishing to communicate the deep beauty of modern physics to the non-mathematician is I suppose equivalent to that faced by a writer attempting to convey the power of Beethoven鈥檚 9th in a magazine article 鈥� it鈥檚 not easy, but we have to try. Because many of the great problems we face in the world today can only be answered by science, and so no matter how arcane the language, the wider public must have confidence in its conclusions.听

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BRIAN

In spite of this strong held belief in the importance of mathematics, Feynman was no elitist. Indeed he revelled in his rebelliousness, reaching out to the wider public beyond science through a number of best selling books which retold the infamous stories and encounters of this remarkable man. The best known of these is Surely You鈥檙e Joking Mr Feynman, still in print today, not so much written by Feynman as dictated to his long time friend Ralph Leighton, the son of one of his Caltech colleagues.

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FEYNMAN - SAFE CRACKER STORY

After the war was over I did some safe opening which I could write a safe cracker book better than any safe cracking book it would start in the beginning and explain how I opened the safe which contained behind it the secret of the atomic bomb, all the secrets, the formulas the rates at which neutrons were liberated from uranium how much uranium you need to make a bomb all the theories all the calculations, the whole damn thing!

0.19

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RALPH

We did feel like they were jewels slipping through out fingers and when we tried to retell them we couldn鈥檛 because not everyone has the art of story telling so we slowly got the idea that maybe ought to record the stories

0.14

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FEYNMAN: SAFE CRACKER STORY

Old Freddy de Hoffman鈥�had 9 filing cabinets鈥�in two rooms full of all the documents of Los Alamos. BUT, carelessly scrawled across the top is pi is equal to 3.14159鈥�I walk up to the first safe and try 314159 鈥� doesn鈥檛 open, 131495 doesn鈥檛 open, 951413 doesn鈥檛 open鈥�20 minutes I鈥檓 there turning pi upside down鈥�nothing. So I start walking out of the office and remembered a book about psychology I read and I said you know, Freddy de Hoffman is just the kind of guy to use as mathematical constant for his safe combination. So the other important mathematics constant is E鈥�so walk back to the safes, 271828 CLICK it opens 鈥�[laughter]

0.52 (courtesy: Ralph Leighton Archive)

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BRIAN

The result was the autobiographical collection of incredible stories called 鈥楽urely You鈥檙e Joking Mr Feynman鈥� 鈥� subtitled, 鈥楢dventures of a Curious Character鈥�, a surprise hit that sold over half听 a million copies鈥�and is still in print today鈥�

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RALPH

They brought it out in January 1985鈥�we thought, January?? What a terrible time to bring out a book, the holidays over, nobody鈥檚 doing anything and now you鈥檙e gonna put out a book? Turns out it was brilliant, since no other books were out at the time, it got noticed and got onto the NYT best seller list and Time magazine as something you needed to read

0.12

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BRIAN

The phrase thinking outside the box has become management speak clich茅 these days, but you almost get the sense that it was invented to describe the Feynman approach to science. He loved, as he called it, to 鈥榩lay with physics鈥� and for him, simply letting his mind wander wherever it went in thinking about nature and contemplating its beauty was as important and valuable as arriving at answers that someone else might define as useful.听

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By jealously protecting his freedom to think, Feynman made significant conceptual contributions to at least two fields that didn鈥檛 even exist when he was alive; Yet they have become two of the most important branches of science and technology today. One is Quantum computing, and the other is Nanotechnology: a field that Feynman is now widely acknowledged to have started, some 50 years ago.

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FEYNMAN PLEASURE with bongos running under

If you expected science to give all the answers to the wonderful questions about what we are, where we鈥檙e going, what the meaning of the universe is and so on, then I think you could easily become disillusioned and then look for some mystic answer to these problems. How a scientist can take a mystic answer I don鈥檛 know because the whole spirit is to understand well, never mind that. Anyhow, I don鈥檛 understand that, but anyhow if you think of it, the way I think of what we鈥檙e doing is we鈥檙e exploring, we鈥檙e trying to find out as much as we can about the world. People say to me, 鈥淎re you looking for the ultimate laws of physics?鈥� No, I鈥檓 not, I鈥檓 just looking to find out more about the world and if it turns out there is a simple ultimate law which explains everything, so be it. That would be very nice to discover. If it turns out it鈥檚 like an onion with millions of layers and we鈥檙e just sick and tired of looking at the layers, then that鈥檚 the way it is, but whatever way it comes out its nature is there and she鈥檚 going to come out the way she is, and therefore when we go to investigate it we shouldn鈥檛 pre-decide what it is we鈥檙e trying to do except to try to find out more about it. If you say your problem is, why do you find out more about it, if you thought you were trying to find out more about it be- cause you鈥檙e going to get an answer to some deep philosophical question, you may be wrong. It may be that you can鈥檛 get an answer to that particular question by finding out more about the character of nature, but I don鈥檛 look at it [like that]. My interest in science is to simply find out about the world, and the more I find out the better it is, like, to find out.

1.31

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END