Feynman Science Quotes

Physics is like sex: sure, it may give some practical results, but that's not why we do it.

The first principle is that you must not fool yourself and you are the easiest person to fool.

I learned very early the difference between knowing the name of something and knowing something.

Religion is a culture of faith; science is a culture of doubt.

I would rather have questions that can't be answered than answers that can't be questioned.

We are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress.

If you thought that science was certain - well, that is just an error on your part.

For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.

You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing — that's what counts. I learned very early the difference between knowing the name of something and knowing something.

What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school... It is my task to convince you not to turn away because you don't understand it. You see my physics students don't understand it... That is because I don't understand it. Nobody does.

I have a friend who's an artist and has sometimes taken a view which I don't agree with very well. He'll hold up a flower and say "look how beautiful it is," and I'll agree. Then he says "I as an artist can see how beautiful this is but you as a scientist take this all apart and it becomes a dull thing," and I think that he's kind of nutty. First of all, the beauty that he sees is available to other people and to me too, I believe. 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 inside, which also have a beauty. I mean it's not just beauty at this dimension, at one centimeter; there's also beauty at smaller dimensions, the inner structure, also the processes. The fact that the colors in the flower evolved in order to attract insects to pollinate it is interesting; it means that insects can see the color. It adds a question: does this aesthetic sense also exist in the lower forms? Why is it aesthetic? All kinds of interesting questions which the science knowledge only adds to the excitement, the mystery and the awe of a flower. It only adds. I don't understand how it subtracts.

Science is like sex: sometimes something useful comes out, but that is not the reason we are doing it.

It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.

To every man is given the key to the gates of heaven. The same key opens the gates of hell. And so it is with science.

Philosophy of science is about as useful to scientists as ornithology is to birds.

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 doesn't seem to me that this fantastically marvelous universe, this tremendous range of time and space and different kinds of animals, and all the different planets, and all these atoms with all their motions, and so on, all this complicated thing can merely be a stage so that God can watch human beings struggle for good and evil - which is the view that religion has. The stage is too big for the drama.

Science is what we have learned about how to keep from fooling ourselves.

Quantum mechanics describes nature as absurd from the point of view of common sense. And yet it fully agrees with experiment. So I hope you can accept nature as She is - absurd.

When it came time for me to give my talk on the subject, I started off by drawing an outline of the cat and began to name the various muscles. The other students in the class interrupt me: "We *know* all that!" "Oh," I say, "you *do*? Then no *wonder* I can catch up with you so fast after you've had four years of biology." They had wasted all their time memorizing stuff like that, when it could be looked up in fifteen minutes.

Science is the belief in the ignorance of experts.

Tell your son to stop trying to fill your head with science — for to fill your heart with love is enough.

Poets say science takes away from the beauty of the stars - mere globs of gas atoms. I too can see the stars on a desert night, and feel them. But do I see less or more? The vastness of the heavens stretches my imagination - stuck on this carousel my little eye can catch one - million - year - old light. A vast pattern - of which I am a part... What is the pattern, or the meaning, or the why? It does not do harm to the mystery to know a little about it. For far more marvelous is the truth than any artists of the past imagined it. Why do the poets of the present not speak of it? What men are poets who can speak of Jupiter if he were a man, but if he is an immense spinning sphere of methane and ammonia must be silent?

Science is a way of trying not to fool yourself. The principle is that you must not fool yourself, and you are the easiest person to fool.

Why make yourself miserable saying things like, "Why do we have such bad luck? What has God done to us? What have we done to deserve this?" - all of which, if you understand reality and take it completely into your heart, are irrelevant and unsolvable. They are just things that nobody can know. Your situation is just an accident of life.

Poets say science takes away from the beauty of the stars - mere globs of gas atoms. I, too, can see the stars on a desert night, and feel them. But do I see less or more?

You know, the most amazing thing happened to me tonight... I saw a car with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!

It doesn't make a difference how beautiful your guess is. It doesn't make a difference how smart you are, who made the guess, or what his name is. If it disagrees with experiment, it's wrong.

Science is the organized skepticism in the reliability of expert opinion.

Philosophers say a great deal about what is absolutely necessary for science, and it is always, so far as one can see, rather naive, and probably wrong.

I can live with doubt and uncertainty and not knowing. I think it's much more interesting to live not knowing than to have answers that might be wrong.

It is surprising that people do not believe that there is imagination in science. It is a very interesting kind of imagination, unlike that of the artist. The great difficulty is in trying to imagine something that you have never seen, that is consistent in every detail with what has already been seen, and that is different from what has been thought of; furthermore, it must be definite and not a vague proposition. That is indeed difficult.

I have no responsibility to live up to what others expect of me. That's their mistake, not my failing.

Knowledge isn't free. You have to pay attention.

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.

We absolutely must leave room for doubt or there is no progress and there is no learning. There is no learning without having to pose a question. And a question requires doubt. People search for certainty. But there is no certainty. People are terrified — how can you live and not know? It is not odd at all. You only think you know, as a matter of fact. And most of your actions are based on incomplete knowledge and you really don't know what it is all about, or what the purpose of the world is, or know a great deal of other things. It is possible to live and not know.

When I tried to show him how an electromagnet works by making a little coil of wire and hanging a nail on a piece of string, I put the voltage on, the nail swung into the coil, and Jerry said, “Ooh! It’s just like fucking!

Once you start doubting, just like you’re supposed to doubt, you ask me if the science is true. You say no, we don’t know what’s true, we’re trying to find out and everything is possibly wrong.

Maybe that’s why young people make success. They don’t know enough. Because when you know enough it’s obvious that every idea that you have is no good.

I think we should teach them [the people] wonders and that the purpose of knowledge is to appreciate wonders even more.

There are thousands of years in the past, and there is an unknown amount of time in the future. There are all kinds of opportunities, and there are all kinds of dangers.

The exception proves that the rule is wrong.” That is the principle of science. If there is an exception to any rule, and if it can be proved by observation, that rule is wrong.

A philosopher once said, "It is necessary for the very existence of science that the same conditions always produce the same results." Well, they don't!

A very great deal more truth can become known than can be proven.

psychoanalysis is not a science: it is at best a medical process, and perhaps even more like witch-doctoring.

We have been led to imagine all sorts of things infinitely more marvelous than the imagining of poets and dreamers of the past. It shows that the imagination of nature is far, far greater than the imagination of man. For instance, how much more remarkable it is for us all to be stuck-half of us upside down-by a mysterious attraction, to a spinning ball that has been swinging in space for billions of years, than to be carried on the back of an elephant supported on a tortoise swimming in a bottomless sea.

I don't mind not knowing. It doesn't scare me.

You see, the chemists have a complicated way of counting: instead of saying "one, two, three, four, five protons," they say, "hydrogen, helium, lithium, beryllium, boron.

I was born not knowing and have only had a little time to change that here and there.

Mathematics is not a science from our point of view, in the sense that it is not a natural science. The test of its validity is not experiment.

THE QUESTION IS, OF COURSE, IS IT GOING TO BE POSSIBLE TO AMALGAMATE EVERYTHING, AND MERELY DISCOVER THAT THIS WORLD REPRESENTS DIFFERENT ASPECTS OF ONE THING?

It doesn't matter how beautiful your theory is ... If it doesn't agree with experiment, it's wrong.

My faith in the expertise of physicists like Richard Feynman, for instance, permits me to endorse—and, if it comes to it, bet heavily on the truth of—a proposition that I don't understand. So far, my faith is not unlike religious faith, but I am not in the slightest bit motivated to go to my death rather than recant the formulas of physics. Watch: E doesn't equal mc2, it doesn't, it doesn't! I was lying, so there!

The only way to have real success in science, the field I'm familiar with, is to describe the evidence very carefully without regard to the way you feel it should be. If you have a theory, you must try to explain what's good and what's bad about it equally. In science, you learn a kind of standard integrity and honesty.

If you thought you were trying to find out more about it because you're gonna get an answer to some deep philosophical question...you may be wrong! It may be that you can't get an answer to that particular question by finding out more about the character of nature. But my interest in science is to simply find out about the world.

The adult Feynman asked: If all scientific knowledge were lost in a cataclysm, what single statement would preserve the most information for the next generations of creatures?

In general, we look for a new law by the following process: First we guess it; then we compute the consequences of the guess to see what would be implied if this law that we guessed is right; then we compare the result of the computation to nature, with experiment or experience, compare it directly with observation, to see if it works. If it disagrees with experiment, it is wrong. In that simple statement is the key to science. It does not make any difference how beautiful your guess is, it does not make any difference how smart you are, who made the guess, or what his name is — if it disagrees with experiment, it is wrong.

I have a friend who's an artist, and he sometimes takes 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. [...] 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.

CURIOSITY DEMANDS THAT WE ASK QUESTIONS, THAT WE TRY TO PUT THINGS TOGETHER AND TRY TO UNDERSTAND THIS MULTITUDE OF ASPECTS AS PERHAPS RESULTING FROM THE ACTION OF A RELATIVELY SMALL NUMBER OF ELEMENTAL THINGS AND FORCES ACTING IN AN INFINITE VARIETY OF COMBINATIONS

Philosophers have said before that one of the fundamental requisites of science is that whenever you set up the same conditions, the same thing must happen. This is simply not true, it is not a fundamental condition of science.

My father had the spirit and integrity of a scientist, but he was a salesman. I remember asking him the question "How can a man of integrity be a salesman?" He said to me, "Frankly, many salesmen in the business are not straightforward--they think it's a better way to sell. But I've tried being straightforward, and I find it has its advantages. In fact, I wouldn't do it any other way. If the customer thinks at all, he'll realize he has had some bad experience with another salesman, but hasn't had that kind of experience with you. So in the end, several customers will stay with you for a long time and appreciate it.

[Doubt] is not a new idea; this is the idea of the age of reason. This is the philosophy that guided the men who made the democracy that we live under. The idea that no one really knew how to run a government led to the idea that we should arrange a system by which new ideas could be developed, tried out, and tossed out if necessary, with more new ideas bought in - a trial-and-error system. This method was a result of the fact that science was already showing itself to be a successful venture at the end of the eighteenth century. Even then it was clear to socially minded people that the openness of possibilities was an opportunity, and that doubt and discussion were essential to progress into the unknown. If we want to solve a problem that we have never solved before, we must leave the door to the unknown ajar...doubt is not to be feared, but welcomed and discussed.

Although my mother didn't know anything about science, she had a great influence on me as well. In particular, she had a wonderful sense of humor, and I learned from her that the highest form of understanding we can achieve are laughter and human compassion

I believe, therefore, that although it is not the case today, that there may some day come a time, I should hope, when it will fully appreciated that the power of governments should be limited; that governments ought not to be empowered to decide the validity of scientific theories, that this is a ridiculous thing for them to try to do; that they are not to decide the description of history or of economic theory or of philosophy.

The trouble with playing a trick on a highly intelligent man like Mr. Teller is that the time it takes him to figure out from the moment that he sees there is something wrong till he understands exactly what happened is too damn small to give you any pleasure!

I've always been rather very one-sided about the science, and when I was younger, I concentrated almost all my effort on it. I didn't have time to learn, and I didn't have much patience for what's called the humanities; even though in the university there were humanities that you had to take, I tried my best to avoid somehow to learn anything and to work on it. It's only afterwards, when I've gotten older and more relaxed that I've spread out a little bit — I've learned to draw, and I read a little bit, but I'm really still a very one-sided person and don't know a great deal. I have a limited intelligence and I've used it in a particular direction.

During a sabbatical he learned enough biology to make a small but genuine contribution to geneticists’ understanding of mutations in DNA.

Is science of any value? I think a power to do something is of value. Whether the result is a good thing or a bad ting depends on how it is used, but the power is a value.

riches have never made people great but love does it every day—we

How I'm rushing through this! How much each sentence in this brief story contains. "The stars are made of the same atoms as the earth." I usually pick one small topic like this to give a lecture on. Poets say science takes away from the beauty of the stars—mere globs of gas atoms. Nothing is "mere." I too can see the stars on a desert night, and feel them. But do I see less or more ? The vastness of the heavens stretches my imagina-tion—stuck on this carousel my little eye can catch one-million-year-old light. A vast pattern—of which I am a part—perhaps my stuff was belched from some forgotten star, as one is belching there. Or see them with the greater eye of Palomar, rushing all apart from some common starting point when they were perhaps all together. What is the pattern, or the meaning, or the why ? It does not do harm to the mystery to know a little about it. For far more marvelous is the truth than any artists of the past imagined! Why do the poets of the present not speak of it ? What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?

After reading the salary, I've decided that I must refuse. The reason I have to refuse a salary like that is I would be able to do what I've always wanted to do- -get a wonderful mistress, put her up in an apartment, buy her nice things.. . With the salary you have offered, I could actually do that, and I know what would happen to me. I'd worry about her, what she's doing; I'd get into arguments when I come home, and so on. All this bother would make me uncomfortable and unhappy. I wouldn't be able to do physics well, and it would be a big mess! What I've always wanted to do would be bad for me, so I've decided that I can't accept your offer.

We cannot predict whether a given photon will arrive at A or B. All we can predict is that out of 100 photons that come down, an average of 4 will be reflected by the front surface. Does this mean that physics, a science of great exactitude, has been reduced to calculating only the probability of an event, and not predicting exactly what will happen? Yes. That's a retreat, but that's the way it is: Nature permits us to calculate only probabilities. Yet science has not collapsed.

I happen to know this, and I happen to know that, and maybe I know that;and I work everything out from there. Tomorrow I may forgot that this is true, but remember that something else is true, so I can reconstruct it all again. I am never quite sure of where I am supposed to begin or where I am supposed to end. I just remember enough all the time so that as the memory fades and some of the pieces fall out I can put the thing back together again every day

You ask me if an ordinary person—by studying hard—would get to be able to imagine these things like I imagine. Of course. I was an ordinary person who studied hard. There's no miracle people. It just happens they got interested in this thing, and they learned all this stuff. They're just people. There's no talent or special miracle ability to understand quantum mechanics or a miracle ability to imagine electromagnetic fields that comes without practice and reading and learning and study. So if you take an ordinary person who's willing to devote a great deal of time and study and work and thinking and mathematics, then he's become a scientist.

It is our responsibility as scientists, knowing the great progress and great value of a satisfactory philosophy of ignorance, the great progress that 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.

You can recognize truth by its beauty and simplicity.” —Richard Feynman, Nobel laureate in physics

We can never be right, we can only prove we're wrong.

We could, of course, use any notation we want; do not laugh at notations; invent them, they are powerful. In fact,mathematics is, to a large extent, invention of better notations.

I now know that there is a happy abundance of science writers who pen the most lucid and thrilling prose—Timothy Ferris, Richard Fortey and Tim Flannery are three that jump out from a single station of the alphabet (and that’s not even to mention the late but godlike Richard Feynman)—but, sadly, none of them wrote any textbook I ever used.

I believe that we must attack these things in which we do not believe. Not attack by the method of cutting off the heads of the people, but attack in the sense of discuss. I believe that we should demand that people try in their own minds to obtain for themselves a more consistent picture of their own world; that they not permit themselves the luxury of having their brain cut in four pieces or two pieces even, and on one side they believe this and on the other side they believe that, but never try to compare the two points of view. Because we have learned that, by trying to put the points of view that we have in our head together and comparing one to the other, we make some progress in understanding and in appreciating where we are and what we are. And I believe that science has remained irrelevant because we wait until somebody asks us questions or until we are invited to give a speech on Einstein’s theory to people who don’t understand Newtonian mechanics, but we never are invited to give an attack on faith healing, or on astrology — on what is the scientific view of astrology today.

The reason Dick's physics was so hard for ordinary people to grasp was that he did not use equations. The usual theoretical physics was done since the time of Newton was to begin by writing down some equations and then to work hard calculating solutions of the equations. This was the way Hans and Oppy and Julian Schwinger did physics. Dick just wrote down the solutions out of his head without ever writing down the equations. He had a physical picture of the way things happen, and the picture gave him the solutions directly with a minimum of calculation. It was no wonder that people who had spent their lives solving equations were baffled by him. Their minds were analytical; his was pictorial.

The scientist has a lot of experience with ignorance and doubt and uncertainty, and this experience is of very great importance, I think. When a scientist doesn’t know the answer to a problem, he is ignorant. When he has a hunch as to what the result is, he is uncertain. And when he is pretty damn sure of what the result is going to be, he is still in some doubt. We have found it of paramount importance that in order to progress, we must recognize our ignorance and leave room for doubt. Scientific knowledge is a body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none absolutely certain. Now, we scientists are used to this, and we take it for granted that it is perfectly consistent to be unsure, that it is possible to live and not know. But I don’t know whether everyone realizes this is true. Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to question — to doubt — to not be sure. I think that it is important that we do not forget this struggle and thus perhaps lose what we have gained.

It is a part of the adventure of science to try to find a limitation in all directions and to stretch the human imagination as far as possible everywhere. Although at every stage it has looked as if such an activity was absurd and useless, it often turns out at least not to be useless.

I think the educational and psychological studies I mentioned are examples of what I would like to call cargo cult science. In the South Seas there is a cargo cult of people. During the war they saw airplanes land with lots of good materials, and they want the same thing to happen now. So they’ve arranged to make things like runways, to put fires along the sides of the runways, to make a wooden hut for a man to sit in, with two wooden pieces on his head like headphones and bars of bamboo sticking out like antennas—he’s the controller—and they wait for the airplanes to land. They’re doing everything right. The form is perfect. It looks exactly the way it looked before. But it doesn’t work. No airplanes land. So I call these things cargo cult science, because they follow all the apparent precepts and forms of scientific investigation, but they’re missing something essential, because the planes don’t land.

If someone were to propose that the planets go around the sun because all planet matter has a kind of tendency for movement, a kind of motility, let us call it an ‘oomph,’ this theory could explain a number of other phenomena as well. So this is a good theory, is it not? No. It is nowhere near as good as the proposition that the planets move around the sun under the influence of a central force which varies exactly inversely as the square of the distance from the center. The second theory is better because it is so specific; it is so obviously unlikely to be the result of chance. It is so definite that the barest error in the movement can show that it is wrong; but the planets could wobble all over the place, and, according to the first theory, you could say, ‘Well, that is the funny behavior of the ‘oomph.

there is a physical problem that is common to many fields, that is very old, and that has not been solved. It is not the problem of finding new fundamental particles, but something left over from a long time ago—over a hundred years. Nobody in physics has really been able to analyze it mathematically satisfactorily in spite of its importance to the sister sciences. It is the analysis of circulating or turbulent fluids.

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. ... My interest in science is to simply find out more about the world.

Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to question — to doubt — to not be sure. I think that it is important that we do not forget this struggle and thus perhaps lose what we have gained.

i have a friend who’s an artist and he’s sometimes taken a view which i don’t agree with very well. he’ll hold up a flower and say, “look how beautiful it is,” and i’ll agree, i think. and he says - “you see, i as an artist can see how beautiful this is, but you as a scientist, oh, take this all apart and it becomes a dull thing.” and i think that he’s kind of nutty. first of all, the beauty that he sees is available to other people and to me, too, i believe, although i might not be quite as refined aesthetically as he is; but i can appreciate the beauty of a flower. at the same time i see much more about the flower than he sees. i can imagine the cells in there, the complicated actions inside which also have a beauty. i mean it’s not just beauty at this dimension of one centimeter, there is also beauty at a smaller dimension, the inner structure. also the processes, the fact that the colors in the flower evolved in order to attract insects to pollinate it is interesting - it means that insects can see the color. it adds a question: does this aesthetic sense also exist in the lower forms? why is it aesthetic? all kinds of interesting questions which shows that a science knowledge only adds to the excitement and mystery and the awe of a flower. it only adds; i don’t understand how it subtracts..

There's a kind of saying that you don't understand its meaning, 'I don't believe it. It's too crazy. I'm not going to accept it.'… You'll have to accept it. It's the way nature works. If you want to know how nature works, we looked at it, carefully. Looking at it, that's the way it looks. You don't like it? Go somewhere else, to another universe where the rules are simpler, philosophically more pleasing, more psychologically easy. I can't help it, okay? If I'm going to tell you honestly what the world looks like to the human beings who have struggled as hard as they can to understand it, I can only tell you what it looks like.

What I got out of that story was something still very new to me: I understood at last what art is really for, at least in certain respects. It gives somebody, individually, pleasure. You can make something that somebody likes so much that they’re depressed, or they’re happy, on account of that damn thing you made! In science, it’s sort of general and large: You don’t know the individuals who have appreciated it directly. I understood that to sell a drawing is not to make money, but to be sure that it’s in the home of someone who really wants it; someone who would feel bad if they didn’t have it. This was interesting.

If you want to win this argument with Dad, look in chapter two of the first book of the Feynman Lectures on Physics. There's a quote there about how philosophers say a great deal about what science absolutely requires, and it is all wrong, because the only rule in science is that the final arbiter is observation - that you just have to look at the world and report what you see. Um... off the top of my head I can't think of where to find something about how it's an ideal of science to settle things by experiment instead of arguments -

Electrons, when they were first discovered, behaved exactly like particles or bullets, very simply. Further research showed, from electron diffraction experiments for example, that they behaved like waves. As time went on there was a growing confusion about how these things really behaved ---- waves or particles, particles or waves? Everything looked like both. This growing confusion was resolved in 1925 or 1926 with the advent of the correct equations for quantum mechanics. Now we know how the electrons and light behave. But what can I call it? If I say they behave like particles I give the wrong impression; also if I say they behave like waves. They behave in their own inimitable way, which technically could be called a quantum mechanical way. They behave in a way that is like nothing that you have seen before. Your experience with things that you have seen before is incomplete. The behavior of things on a very tiny scale is simply different. An atom does not behave like a weight hanging on a spring and oscillating. Nor does it behave like a miniature representation of the solar system with little planets going around in orbits. Nor does it appear to be somewhat like a cloud or fog of some sort surrounding the nucleus. It behaves like nothing you have seen before. There is one simplication at least. Electrons behave in this respect in exactly the same way as photons; they are both screwy, but in exactly in the same way…. The difficulty really is psychological and exists in the perpetual torment that results from your saying to yourself, "But how can it be like that?" which is a reflection of uncontrolled but utterly vain desire to see it in terms of something familiar. I will not describe it in terms of an analogy with something familiar; I will simply describe it. There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics. So do not take the lecture too seriously, feeling that you really have to understand in terms of some model what I am going to describe, but just relax and enjoy it. I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself, if you can possible avoid it, "But how can it be like that?" because you will get 'down the drain', into a blind alley from which nobody has escaped. Nobody knows how it can be like that.

Another most interesting change in the ideas and philosophy of science brought about by quantum mechanics is this: it is not possible to predict exactly what will happen in any circumstance. For example, it is possible to arrange an atom which is ready to emit light, and we can measure when it has emitted light by picking up a photon particle, which we shall describe shortly. We cannot, however, predict when it is going to emit the light or, with several atoms, which one is going to. You may say that this is because there are some internal "wheels" which we have not looked at closely enough. No, there are no internal wheels; nature, as we understand it today, behaves in such a way that it is fundamentally impossible to make a precise prediction of exactly what will happen in a given experiment.

For instance, the scientific article may say, 'The radioactive phosphorus content of the cerebrum of the rat decreases to one- half in a period of two weeks.' Now what does that mean? It means that phosphorus that is in the brain of a rat—and also in mine, and yours—is not the same phosphorus as it was two weeks ago. It means the atoms that are in the brain are being replaced: the ones that were there before have gone away. So what is this mind of ours: what are these atoms with consciousness? Last week's potatoes! They now can remember what was going on in my mind a year ago—a mind which has long ago been replaced. To note that the thing I call my individuality is only a pattern or dance, that is what it means when one discovers how long it takes for the atoms of the brain to be replaced by other atoms. The atoms come into my brain, dance a dance, and then go out—there are always new atoms, but always doing the same dance, remembering what the dance was yesterday.

That is the idea that we all hope you have learned in studying science in school—we never explicitly say what this is, but just hope that you catch on by all the examples of scientific investigation. It is interesting, therefore, to bring it out now and speak of it explicitly. It’s a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty—a kind of leaning over backwards. For example, if you’re doing an experiment, you should report everything that you think might make it invalid—not only what you think is right about it: other causes that could possibly explain your results; and things you thought of that you’ve eliminated by some other experiment, and how they worked—to make sure the other fellow can tell they have been eliminated. Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can—if you know anything at all wrong, or possibly wrong—to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition. In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another. The first principle is that you must not fool yourself—and you are the easiest person to fool. So you have to be very careful about that. After you’ve not fooled yourself, it’s easy not to fool other scientists... You just have to be honest in a conventional way after that.

A philosopher once said 'It is necessary for the very existence of science that the same conditions always produce the same results'. Well, they do not. You set up the circumstances, with the same conditions every time, and you cannot predict behind which hole you will see the electron. Yet science goes on in spite of it - although the same conditions do not always produce the same results. <...> What is necessary 'for the very existence of science', and what the characteristics of nature are, are not to be determined by pompous preconditions, they are determined always by the material with which we work, by nature herself. We look, and we see what we find, and we cannot say ahead of time successfully what it is going to look like. <...> If science is to progress, what we need is the ability to experiment, honesty in reporting results - the results must be reported without somebody saying what they would like the results to have been - and finally - an important thing - the intelligence to interpret the results.

[Paul Olum] was president of the University of Oregon when he heard of [Richard] Feynman’s death. He realized that the young genius he had met at Princeton had become a part of him, impossible to extricate. “My wife died three years ago, also of cancer,” he said. ... I think about her a lot. I have to admit I have Dick’s books and other things of Dick’s. I have all of the Feynman lectures and other stuff. And there are things that have pictures of Dick on them. The article in Science about the Challenger episode. And also some of the recent books. I get a terrible feeling every time I look at them. How could someone like Dick Feynman be dead? This great and wonderful mind. This extraordinary feeling for things and ability is in the ground and there’s nothing there anymore. It’s an awful feeling. And I feel it—— A lot of people have died and I know about it. My parents are both dead and I had a younger brother who is dead. But I have this feeling about just two people. About my wife and about Dick. I suppose, although this wasn’t quite like childhood, it was graduate students together, and I do have more—— I don’t know, romantic, or something, feelings about Dick, and I have trouble realizing that he’s dead. He was such an extraordinarily special person in the universe. Gleick, James (2011-02-22). Genius: The Life and Science of Richard Feynman (p. 145). Open Road Media. Kindle Edition.

For example, there was a book that started out with four pictures: first there was a wind-up toy; then there was an automobile; then there was a boy riding a bicycle; then there was something else. And underneath each picture, it said "What makes it go?" I thought, I know what it is: They're going to talk about mechanics, how the springs work inside the toy; about chemistry, how the engine of an automobile works; and biology, about how the muscles work. It was the kind of thing my father would have talked about: "What makes it go? Everything goes because the sun is shining." And then we would have fun discussing it: "No, the toy goes becaues the spring is wound up, I would say. "How did the spring get would up" he would ask. "I wound it up" "And how did you get moving?" "From eating" "And food grows only because the sun is shining. So it's because the sun is shining that all these things are moving" That would get the concept across that motion is simply the transformation of the sun's power. I turned the page. The answer was, for the wind-up toy, "Energy makes it go." And for the boy on the bicycle, "Energy makes it go." For everything "Energy makes it go." Now that doesn't mean anything. Suppose it's "Wakalixes." That's the general principle: "Wakalixes makes it go." There is no knowledge coming in. The child doesn't learn anything; it's just a word What the should have done is to look at the wind-up toy, see that there are springs inside, learn about springs, learn about wheels, and never mind "energy". Later on, when the children know something about how the toy actually works, they can discuss the more general principles of energy. It is also not even true that "energy makes it go", because if it stops, you could say, "energy makes it stop" just as well. What they're talking about is concentrated energy being transformed into more dilute forms, which is a very subtle aspect of energy. Energy is neither increased nor decreased in these examples; it's just changed from one form to another. And when the things stop, the energy is changed into heat, into general chaos.

My four things I care about are truth, meaning, fitness and grace. [...] Sam [Harris] would like to make an argument that the better and more rational our thinking is, the more it can do everything that religion once did. [...] I think about my personal physics hero, Dirac – who was the guy who came up with the equation for the electron, less well-known than the Einstein equations but arguably even more beautiful...in order to predict that, he needed a positively-charged and a negatively-charged particle, and the only two known at the time were the electron and the proton to make up, let's say, a hydrogen atom. Well, the proton is quite a bit heavier than the electron and so he told the story that wasn't really true, where the proton was the anti-particle of the electron, and Heisenberg pointed out that that couldn't be because the masses are too far off and they have to be equal. Well, a short time later, the anti-electron -- the positron, that is -- was found, I guess by Anderson at Caltech in the early 30s and then an anti-proton was created some time later. So it turned out that the story had more meaning than the exact version of the story...so the story was sort of more true than the version of the story that was originally told. And I could tell you a similar story with Einstein, I could tell it to you with Darwin, who, you know, didn't fully understand the implications of his theory, as is evidenced by his screwing up a particular kind of orchid in his later work...not understanding that his theory completely explained that orchid! So there's all sorts of ways in which we get the...the truth wrong the first several times we try it, but the meaning of the story that we tell somehow remains intact. And I think that that's a very difficult lesson for people who just want to say, 'Look, I want to'...you know, Feynman would say, "If an experiment disagrees with you, then you're wrong' and it's a very appealing story to tell to people – but it's also worth noting that Feynman never got a physical law of nature and it may be that he was too wedded to this kind of rude judgment of the unforgiving. Imagine you were innovating in Brazilian jiu-jitsu. The first few times might not actually work. But if you told yourself the story, 'No, no, no – this is actually genius and it's working; no, you just lost three consecutive bouts' -- well, that may give you the ability to eventually perfect the move, perfect the technique, even though you were lying to yourself during the period in which it was being set up. It's a little bit like the difference between scaffolding and a building. And too often, people who are crazy about truth reject scaffolding, which is an intermediate stage in getting to the final truth.