Quotes from The Feynman Lectures on Physics Vol 1

“psychoanalysis is not a science: it is at best a medical process, and perhaps even more like witch-doctoring.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“It is probably better to realize that the probability concept is in a sense subjective, that it is always based on uncertain knowledge, and that its quantitative evaluation is subject to change as we obtain more information.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“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.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“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.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“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.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“There was an interesting early relationship between physics and biology in which biology helped physics in the discovery of the conservation of energy, which was first demonstrated by Mayer in connection with the amount of heat taken in and given out by a living creature.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“No phenomenon directly involving a frequency has yet been detected above approximately 10^12 cycles per second. We only deduce the higher frequencies from the energy of the particles, by a rule which assumes that the particle-wave idea of quantum mechanics is valid.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“One of the most impressive discoveries was the origin of the energy of the stars, that makes them continue to burn. One of the men who discovered this was out with his girlfriend the night after he realized that nuclear reactions must be going on in the stars in order to make them shine. She said “Look at how pretty the stars shine!” He said “Yes, and right now I am the only man in the world who knows why they shine.” She merely laughed at him. She was not impressed with being out with the only man who, at that moment, knew why stars shine. Well, it is sad to be alone, but that is the way it is in this world.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“else can you do with the law of gravitation? If we look at the moons of Jupiter we can understand everything about the way they move around that planet. Incidentally, there was once a certain difficulty with the moons of Jupiter that is worth remarking on. These satellites were studied very carefully by Rømer, who noticed that the moons sometimes seemed to be ahead of schedule, and sometimes behind. (One can find their schedules by waiting a very long time and finding out how long it takes on the average for the moons to go around.) Now they were ahead when Jupiter was particularly close to the earth and they were behind when Jupiter was farther from the earth. This would have been a very difficult thing to explain according to the law of gravitation—it would have been, in fact, the death of this wonderful theory if there were no other explanation. If a law does not work even in one place where it ought to, it is just wrong. But the reason for this discrepancy was very simple and beautiful: it takes a little while to see the moons of Jupiter because of the time it takes light to travel from Jupiter to the earth. When Jupiter is closer to the earth the time is a little less, and when it is farther from the earth, the time is more. This is why moons appear to be, on the average, a little ahead or a little behind, depending on whether they are closer to or farther from the earth. This phenomenon showed that light does not travel instantaneously, and furnished the first estimate of the speed of light. This was done in 1676.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“What else can you do with the law of gravitation? If we look at the moons of Jupiter we can understand everything about the way they move around that planet. Incidentally, there was once a certain difficulty with the moons of Jupiter that is worth remarking on. These satellites were studied very carefully by Rømer, who noticed that the moons sometimes seemed to be ahead of schedule, and sometimes behind. (One can find their schedules by waiting a very long time and finding out how long it takes on the average for the moons to go around.) Now they were ahead when Jupiter was particularly close to the earth and they were behind when Jupiter was farther from the earth. This would have been a very difficult thing to explain according to the law of gravitation—it would have been, in fact, the death of this wonderful theory if there were no other explanation. If a law does not work even in one place where it ought to, it is just wrong. But the reason for this discrepancy was very simple and beautiful: it takes a little while to see the moons of Jupiter because of the time it takes light to travel from Jupiter to the earth. When Jupiter is closer to the earth the time is a little less, and when it is farther from the earth, the time is more. This is why moons appear to be, on the average, a little ahead or a little behind, depending on whether they are closer to or farther from the earth. This phenomenon showed that light does not travel instantaneously, and furnished the first estimate of the speed of light. This was done in 1676.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“A description of nature is what we are concerned with here. From this point
of view, then, a gas, and indeed all matter, is a myriad of moving particles. Thus
many of the things we saw while standing at the seashore can immediately be
connected. First the pressure: this comes from the collisions of the atoms with
the walls or whatever; the drift of the atoms, if they are all moving in one direc-
tion on the average, is wind; the random internal motions are the heat. There are
waves of excess density, where too many particles have collected, and so as they
Tush off they push up piles of particles farther out, and so on. This wave of excess
density is sound. It is a tremendous achievement to be able to understand so much.
Some of these things were described in the previous chapter.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or atomic fact, or whatever you wish to call it) that all things are made of atoms...(italics in original).”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“Only with quantitative observations can one arrive at quantitative relationships, which are the heart of physics.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“Even a very small effect sometimes requires profound changes in our ideas”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“...we do not yet know all the basic laws: there is an expanding frontier of ignorance”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

“Now the jiggling motion is what we represent as heat:
when we increase the temperature, we increase the motion. If we heat the water,
the jiggling increases and the volume between the atoms increases, and if the
heating continues there comes a time when the pull between the molecules is not
enough to hold them together and they do fly apart and become separated from
one another. Of course, this is how we manufacture steam out of water—by
increasing the temperature; the particles fly apart because of the increased motion.”
― Richard Feynman, quote from The Feynman Lectures on Physics Vol 1

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