Richard Feynman citations

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Richard Feynman

Date de naissance: 11. mai 1918
Date de décès: 15. février 1988
Autres noms:Richard Feynman Philips,Richard Phillips Feynman,Ричард Филлипс Фейнман

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Richard Phillips Feynman est l'un des physiciens les plus influents de la seconde moitié du XXe siècle, en raison notamment de ses travaux sur l'électrodynamique quantique, les quarks et l'hélium superfluide.

Il reformula entièrement la mécanique quantique à l'aide de son intégrale de chemin qui généralise le principe de moindre action de la mécanique classique et inventa les diagrammes qui portent son nom et qui sont désormais largement utilisés en théorie quantique des champs .

Pendant la seconde guerre mondiale, il est impliqué dans le développement de la bombe atomique américaine. Après la Seconde Guerre mondiale, il enseigna à l'université Cornell puis au Caltech où il effectua des travaux fondamentaux notamment dans la théorie de la superfluidité et des quarks. Sin-Itiro Tomonaga, Julian Schwinger et lui sont colauréats du prix Nobel de physique de 1965 pour leurs travaux en électrodynamique quantique. Vers la fin de sa vie, son action au sein de la commission d'enquête sur l'accident de la navette spatiale Challenger l'a fait connaître du grand public américain.

Pédagogue remarquable, il est le rédacteur de nombreux ouvrages de vulgarisation reconnus. Parmi ces livres, les Feynman lectures on physics, un cours de physique de niveau universitaire qui, depuis sa parution, est devenu un classique pour tous les étudiants de premier cycle en physique et leurs professeurs. Il raconte aussi ses nombreuses aventures dans plusieurs ouvrages : Surely You're Joking, Mr. Feynman! et What Do You Care What Other People Think? . Ce tome est lié au soutien moral que sa première épouse Arlene lui donnait, l'encourageant par ce biais dans sa poursuite intellectuelle en tant que libre-penseur.

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Citations Richard Feynman

„il s’agit en quelque sorte d’une caractéristique de la simplicité de la nature.“

— Richard Feynman
Sur le fait qu'il existe de nombreuses manières de formuler une même théorie, Discours de réception du prix Nobel.

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„We can deduce, often, from one part of physics like the law of gravitation, a principle which turns out to be much more valid than the derivation.“

— Richard Feynman
Context: Now we have a problem. We can deduce, often, from one part of physics like the law of gravitation, a principle which turns out to be much more valid than the derivation. This doesn't happen in mathematics, that the theorems come out in places where they're not supposed to be! chapter 2, “ The Relation of Mathematics to Physics http://www.youtube.com/watch?v=M9ZYEb0Vf8U” referring to the law of conservation of angular momentum

„God was always invented to explain mystery. God is always invented to explain those things that you do not understand.“

— Richard Feynman
Context: God was always invented to explain mystery. God is always invented to explain those things that you do not understand. Now, when you finally discover how something works, you get some laws which you're taking away from God; you don't need him anymore. But you need him for the other mysteries. So therefore you leave him to create the universe because we haven't figured that out yet; you need him for understanding those things which you don't believe the laws will explain, such as consciousness, or why you only live to a certain length of time — life and death — stuff like that. God is always associated with those things that you do not understand. Therefore I don't think that the laws can be considered to be like God because they have been figured out. interview published in Superstrings: A Theory of Everything? (1988) edited by Paul C. W. Davies and Julian R. Brown, p. 208-209

„Feynman is the young American professor, half genius and half buffoon, who keeps all physicists and their children amused with his effervescent vitality.“

— Richard Feynman
Context: Feynman is the young American professor, half genius and half buffoon, who keeps all physicists and their children amused with his effervescent vitality. He has, however, as I have recently learned, a great deal more to him than that, and you may be interested in his story. The part of it with which I am concerned began when he arrived at Los Alamos; there he found and fell in love with a brilliant and beautiful girl, who was tubercular and had been exiled to New Mexico in the hope of stopping the disease. When Feynman arrived, things had got so bad that the doctors gave her only a year to live, but he determined to marry her and marry her he did; and for a year and a half, while working at full pressure on the Project, he nursed her and made her days cheerful. She died just before the end of the war. Freeman Dyson, in letter to his parents on 8 March 1948, as published in From Eros to Gaia (1992), p. 325 In 1988 he revised his statement and declared that:

„We are at the very beginning of time for the human race. It is not unreasonable that we grapple with problems. But there are tens of thousands of years in the future. Our responsibility is to do what we can, learn what we can, improve the solutions, and pass them on.“

— Richard Feynman
Context: We are at the very beginning of time for the human race. It is not unreasonable that we grapple with problems. But there are tens of thousands of years in the future. Our responsibility is to do what we can, learn what we can, improve the solutions, and pass them on. ... It is our responsibility to leave the people of the future a free hand. In the impetuous youth of humanity, we can make grave errors that can stunt our growth for a long time. This we will do if we say we have the answers now, so young and ignorant as we are. If we suppress all discussion, all criticism, proclaiming "This is the answer, my friends; man is saved!" we will doom humanity for a long time to the chains of authority, confined to the limits of our present imagination. It has been done so many times before. ... It is our responsibility as scientists, knowing the great progress which comes from a satisfactory philosophy of ignorance, the great progress which is the fruit of freedom of thought, to proclaim the value of this freedom; to teach how doubt is not to be feared but welcomed and discussed; and to demand this freedom as our duty to all coming generations.

„Why should we care about Feynman? What was so special about him? Why did he become a public icon, standing with Albert Einstein and Stephen Hawking as the Holy Trinity of twentieth-century physics?“

— Richard Feynman
Context: Why should we care about Feynman? What was so special about him? Why did he become a public icon, standing with Albert Einstein and Stephen Hawking as the Holy Trinity of twentieth-century physics? The public has demonstrated remarkably good taste in choosing its icons. All three of them are genuinely great scientists, with flashes of true genius as well as solid accomplishments to their credit. But to become an icon, it is not enough to be a great scientist. There are many other scientists, not so great as Einstein but greater than Hawking and Feynman, who did not become icons.... Scientists who become icons must not only be geniuses but also performers, playing to the crowd and enjoying public acclaim. Einstein and Feynman both grumbled about the newspaper and radio reporters who invaded their privacy, but both gave the reporters what the public wanted, sharp and witty remarks that would make good headlines. Hawking in his unique way also enjoys the public adulation that his triumph over physical obstacles has earned for him. I will never forget the joyful morning in Tokyo when Hawking went on a tour of the streets in his wheelchair and the Japanese crowds streamed after him, stretching out their hands to touch his chair. Einstein, Hawking, and Feynman shared an ability to break through the barriers that separated them from ordinary people. The public responded to them because they were regular guys, jokers as well as geniuses. The third quality that is needed for a scientist to become a public icon is wisdom. Besides being a famous joker and a famous genius, Feynman was also a wise human being whose answers to serious questions made sense. To me and to hundreds of other students who came to him for advice, he spoke truth. Like Einstein and Hawking, he had come through times of great suffering, nursing Arline through her illness and watching her die, and emerged stronger. Behind his enormous zest and enjoyment of life was an awareness of tragedy, a knowledge that our time on earth is short and precarious. The public made him into an icon because he was not only a great scientist and a great clown but also a great human being and a guide in time of trouble. Other Feynman books have portrayed him as a scientific wizard and as a storyteller. This collection of letters shows us for the first time the son caring for his father and mother, the father caring for his wife and children, the teacher caring for his students, the writer replying to people throughout the world who wrote to him about their problems and received his full and undivided attention. Freeman Dyson, in "Wise Man" http://www.nybooks.com/articles/18350, The New York Review of Books (20 October 2005)

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„And therefore when we go to investigate we shouldn’t pre-decide what it is we are trying to do except to find out more about it“

— Richard Feynman
Context: People say to me, "Are you looking for the ultimate laws of physics?" No, I'm not. I'm 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's like an onion with millions of layers and we're just sick and tired of looking at the layers, then that's the way it is!… And therefore when we go to investigate we shouldn’t pre-decide what it is we are trying to do except to find out more about it… My interest in science is to simply find out more about the world. p. 251-252, from interview in "The Pleasure of Finding Things Out" (1981): video http://www.youtube.com/watch?v=NEwUwWh5Xs4&t=45m21s (Also in book The Pleasure of Finding Things Out (1999) p. 23.)

„It is not unscientific to make a guess, although many people who are not in science think it is.“

— Richard Feynman
Context: It is not unscientific to make a guess, although many people who are not in science think it is. Some years ago I had a conversation with a layman about flying saucers — because I am scientific I know all about flying saucers! I said “I don’t think there are flying saucers”. So my antagonist said, “Is it impossible that there are flying saucers? Can you prove that it’s impossible?” “No”, I said, “I can’t prove it’s impossible. It’s just very unlikely”. At that he said, “You are very unscientific. If you can’t prove it impossible then how can you say that it’s unlikely?” But that is the way that is scientific. It is scientific only to say what is more likely and what less likely, and not to be proving all the time the possible and impossible. To define what I mean, I might have said to him, "Listen, I mean that from my knowledge of the world that I see around me, I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence." It is just more likely. That is all. chapter 7, “Seeking New Laws,” p. 165-166: video http://www.youtube.com/watch?v=-2NnquxdWFk&t=37m21s

„It is important to realize that in physics today, we have no knowledge what energy is.“

— Richard Feynman
Context: It is important to realize that in physics today, we have no knowledge what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. volume I; lecture 4, "Conservation of Energy"; section 4-1, "What is energy?"; p. 4-2

„Have no respect whatsoever for authority; forget who said it and instead look what he starts with, where he ends up, and ask yourself, "Is it reasonable?"“

— Richard Feynman
Context: Doubting the great Descartes … was a reaction I learned from my father: Have no respect whatsoever for authority; forget who said it and instead look what he starts with, where he ends up, and ask yourself, "Is it reasonable?" "What Do You Care What Other People Think?", p. 28-29

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„Mathematics is not just a language. Mathematics is a language plus reasoning.“

— Richard Feynman
Context: Mathematics is not just a language. Mathematics is a language plus reasoning. It's like a language plus logic. Mathematics is a tool for reasoning. It's, in fact, a big collection of the results of some person's careful thought and reasoning. By mathematics, it is possible to connect one statement to another. chapter 2, “The Relation of Mathematics to Physics”

„Agnostic for me would be trying to weasel out and sound a little nicer than I am about this.“

— Richard Feynman
Context: [I call myself] an atheist. Agnostic for me would be trying to weasel out and sound a little nicer than I am about this. Response when asked whether he called himself an atheist or an agnostic. The Voice of Genius: Conversations with Nobel Scientists and Other Luminaries by Denis Brian (1995), Basic Books, p. 49.

„If our small minds, for some convenience, divide this glass of wine, this universe, into parts — physics, biology, geology, astronomy, psychology, and so on — remember that nature does not know it!“

— Richard Feynman
Context: A poet once said, "The whole universe is in a glass of wine." We will probably never know in what sense he meant that, for poets do not write to be understood. But it is true that if we look at a glass of wine closely enough we see the entire universe. There are the things of physics: the twisting liquid which evaporates depending on the wind and weather, the reflections in the glass, and our imagination adds the atoms. The glass is a distillation of the Earth's rocks, and in its composition we see the secrets of the universe's age, and the evolution of stars. What strange arrays of chemicals are in the wine? How did they come to be? There are the ferments, the enzymes, the substrates, and the products. There in wine is found the great generalization: all life is fermentation. Nobody can discover the chemistry of wine without discovering, as did Louis Pasteur, the cause of much disease. How vivid is the claret, pressing its existence into the consciousness that watches it! If our small minds, for some convenience, divide this glass of wine, this universe, into parts — physics, biology, geology, astronomy, psychology, and so on — remember that nature does not know it! So let us put it all back together, not forgetting ultimately what it is for. Let it give us one more final pleasure: drink it and forget it all! volume I; lecture 3, "The Relation of Physics to Other Sciences"; section 3-7, "How did it get that way?"; p. 3-10

„This is not yet a scientific age.“

— Richard Feynman
Context: Is no one inspired by our present picture of the universe? This value of science remains unsung by singers, you are reduced to hearing not a song or poem, but an evening lecture about it. This is not yet a scientific age.

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