Tag Archives: Richard Feynman

Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher by Richard Feynman

Summary

  1. A distillation of some of the key principles that Feynman covers in his lectures

Key Takeaways

  1. Feynman was a theoretical physicist par excellence. Newton had been both experimentalist and theorist in equal measure. Einstein was quite simply contemptuous of experiment, preferring to put his faith in pure thought. Feynman was driven to develop a deep theoretical understanding of nature, but he always remained close to the real and often grubby world of experimental results.
  2. Feynman diagrams are a symbolic but powerfully heuristic way of picturing what is going on when electrons, photons, and other particles interact with each other. These days Feynman diagrams are a routine aid to calculation, but in the early 1950s they marked a startling departure from the traditional way of doing theoretical physics.
  3. The Feynman style can best be described as a mixture of reverence and disrespect for received wisdom. Physics is an exact science, and the existing body of knowledge, while incomplete, can’t simply be shrugged aside. Feynman acquired a formidable grasp of the accepted principles of physics at a very young age, and he chose to work almost entirely on conventional problems. He was not the sort of genius to beaver away in isolation in a backwater of the discipline and to stumble across the profoundly new. His special talent was to approach essentially mainstream topics in an idiosyncratic way. This meant eschewing existing formalisms and developing his own highly intuitive approach. Whereas most theoretical physicists rely on careful mathematical calculation to provide a guide and a crutch to take them into unfamiliar territory, Feynman’s attitude was almost cavalier. You get the impression that he could read nature like a book and simply report on what he found, without the tedium of complex analysis.
  4. Physics is continually linked to other sciences while leaving the reader in no doubt about which is the fundamental discipline.
  5. Right at the beginning of Six Easy Pieces we learn how all physics is rooted in the notion of law—the existence of an ordered universe that can be understood by the application of rational reasoning. However, the laws of physics are not transparent to us in our direct observations of nature.
  6. A great unifying theme among particle physicists has been the role of symmetry and conservation laws in bringing order to the subatomic zoo.
  7. First figure out why you want the students to learn the subject and what you want them to know, and the method will result more or less by common sense.
  8. “The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous.” (Gibbon)
  9. You might ask why we cannot teach physics by just giving the basic laws on page one and then showing how they work in all possible circumstances, as we do in Euclidean geometry, where we state the axioms and then make all sorts of deductions. (So, not satisfied to learn physics in four years, you want to learn it in four minutes?) We cannot do it in this way for two reasons. First, we do not yet know all the basic laws: there is an expanding frontier of ignorance. Second, the correct statement of the laws of physics involves some very unfamiliar ideas which require advanced mathematics for their description. Therefore, one needs a considerable amount of preparatory training even to learn what the words mean. No, it is not possible to do it that way. We can only do it piece by piece. Each piece, or part, of the whole of nature is always merely an approximation to the complete truth, or the complete truth so far as we know it. In fact, everything we know is only some kind of approximation, because we know that we do not know all the laws as yet. Therefore, things must be learned only to be unlearned again or, more likely, to be corrected. The principle of science, the definition, almost, is the following: The test of all knowledge is experiment. Experiment is the sole judge of scientific “truth.” But what is the source of knowledge? Where do the laws that are to be tested come from? Experiment, itself, helps to produce these laws, in the sense that it gives us hints. But also needed is imagination to create from these hints the great generalizations—to guess at the wonderful, simple, but very strange patterns beneath them all, and then to experiment to check again whether we have made the right guess. This imagining process is so difficult that there is a division of labor in physics: there are theoretical physicists who imagine, deduce, and guess at new laws, but do not experiment; and then there are experimental physicists who experiment, imagine, deduce, and guess.
  10. Now, what should we teach first? Should we teach the correct but unfamiliar law with its strange and difficult conceptual ideas, for example the theory of relativity, four-dimensional space-time, and so on? Or should we first teach the simple “constant-mass” law, which is only approximate, but does not involve such difficult ideas? The first is more exciting, more wonderful, and more fun, but the second is easier to get at first, and is a first step to a real understanding of the first idea. This point arises again and again in teaching physics. At different times we shall have to resolve it in different ways, but at each stage it is worth learning what is now known, how accurate it is, how it fits into everything else, and how it may be changed when we learn more.
  11. 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 the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.
  12. This means that when we compress a gas slowly, the temperature of the gas increases. So, under slow compression, a gas will increase in temperature, and under slow expansion it will decrease in temperature.
  13. The difference between solids and liquids is, then, that in a solid the atoms are arranged in some kind of an array, called a crystalline array, and they do not have a random position at long distances; the position of the atoms on one side of the crystal is determined by that of other atoms millions of atoms away on the other side of the crystal.
  14. Most simple substances, with the exception of water and type metal, expand upon melting, because the atoms are closely packed in the solid crystal and upon melting need more room to jiggle around, but an open structure collapses, as in the case of water.
  15. As we decrease the temperature, the vibration decreases and decreases until, at absolute zero, there is a minimum amount of vibration that the atoms can have, but not zero. This minimum amount of motion that atoms can have is not enough to melt a substance, with one exception: helium. Helium merely decreases the atomic motions as much as it can, but even at absolute zero there is still enough motion to keep it from freezing. Helium, even at absolute zero, does not freeze, unless the pressure is made so great as to make the atoms squash together. If we increase the pressure, we can make it solidify.
  16. The other processes so far described are called physical processes, but there is no sharp distinction between the two. (Nature does not care what we call it, she just keeps on doing it.)
  17. Carbon attracts oxygen much more than oxygen attracts oxygen or carbon attracts carbon. Therefore in this process the oxygen may arrive with only a little energy, but the oxygen and carbon will snap together with a tremendous vengeance and commotion, and everything near them will pick up the energy. A large amount of motion energy, kinetic energy, is thus generated. This of course is burning; we are getting heat from the combination of oxygen and carbon. The heat is ordinarily in the form of the molecular motion of the hot gas, but in certain circumstances it can be so enormous that it generates light. That is how one gets flames.
  18. if we look at very tiny particles (colloids) in water through an excellent microscope, we see a perpetual jiggling of the particles, which is the result of the bombardment of the atoms. This is called the Brownian motion.
  19. Everything is made of atoms. That is the key hypothesis. The most important hypothesis in all of biology, for example, is that everything that animals do, atoms do. In other words, there is nothing that living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics. This was not known from the beginning: it took some experimenting and theorizing to suggest this hypothesis, but now it is accepted, and it is the most useful theory for producing new ideas in the field of biology.
  20. A few hundred years ago, a method was devised to find partial answers to such questions. Observation, reason, and experiment make up what we call the scientific method.
  21. What do we mean by “understanding” something? We can imagine that this complicated array of moving things which constitutes “the world” is something like a great chess game being played by the gods, and we are observers of the game. We do not know what the rules of the game are; all we are allowed to do is to watch the playing. Of course, if we watch long enough, we may eventually catch on to a few of the rules. The rules of the game are what we mean by fundamental physics…If we know the rules, we consider that we “understand” the world.
  22. At first the phenomena of nature were roughly divided into classes, like heat, electricity, mechanics, magnetism, properties of substances, chemical phenomena, light or optics, x-rays, nuclear physics, gravitation, meson phenomena, etc. However, the aim is to see complete nature as different aspects of one set of phenomena. That is the problem in basic theoretical physics today—to find the laws behind experiment; to amalgamate these classes.
  23. Some historic examples of amalgamation are the following. First, take heat and mechanics. When atoms are in motion, the more motion, the more heat the system contains, and so heat and all temperature effects can be represented by the laws of mechanics. Another tremendous amalgamation was the discovery of the relation between electricity, magnetism, and light, which were found to be different aspects of the same thing, which we call today the electromagnetic field. Another amalgamation is the unification of chemical phenomena, the various properties of various substances, and the behavior of atomic particles, which is in the quantum mechanics of chemistry. 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? Nobody knows. All we know is that as we go along, we find that we can amalgamate pieces, and then we find some pieces that do not fit, and we keep trying to put the jigsaw puzzle together. Whether there are a finite number of pieces, and whether there is even a border to the puzzle, are of course unknown. It will never be known until we finish the picture, if ever. What we wish to do here is to see to what extent this amalgamation process has gone on, and what the situation is at present, in understanding basic phenomena in terms of the smallest set of principles. To express it in a simple manner, what are things made of and how few elements are there?
  24. Because the chemical properties depend upon the electrons on the outside, and in fact only upon how many electrons there are. So the chemical properties of a substance depend only on a number, the number of electrons.
  25. Magnetic influences have to do with charges in relative motion, so magnetic forces and electric forces can really be attributed to one field, as two different aspects of exactly the same thing.
  26. X-rays are nothing but very high-frequency light.
  27. The mechanical rules of “inertia” and “forces” are wrong—Newton’s laws are wrong—in the world of atoms. Instead, it was discovered that things on a small scale behave nothing like things on a large scale. That is what makes physics difficult—and very interesting. It is hard because the way things behave on a small scale is so ”unnatural“; we have no direct experience with it. Here things behave like nothing we know of, so that it is impossible to describe this behavior in any other than analytic ways. It is difficult, and takes a lot of imagination. Quantum mechanics has many aspects. In the first place, the idea that a particle has a definite location and a definite speed is no longer allowed; that is wrong.
  28. there is a rule in quantum mechanics that says that one cannot know both where something is and how fast it is moving.
  29. 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.
  30. One of the consequences is that things which we used to consider as waves also behave like particles, and particles behave like waves; in fact everything behaves the same way. There is no distinction between a wave and a particle. So quantum mechanics unifies the idea of the field and its waves, and the particles, all into one.
  31. We have been seeking a Mendeléev-type chart for the new particles. One such chart of the new particles was made independently by Gell-Mann in the USA and Nishijima in Japan. The basis of their classification is a new number, like the electric charge, which can be assigned to each particle, called its “strangeness,” S. This number is conserved, like the electric charge, in reactions which take place by nuclear forces.
  32. What is this “zero mass”? The masses given here are the masses of the particles at rest. The fact that a particle has zero mass means, in a way, that it cannot be at rest. A photon is never at rest; it is always moving at 186,000 miles a second.
  33. In fact, there seem to be just four kinds of interaction between particles which, in the order of decreasing strength, are the nuclear force, electrical interactions, the beta-decay interaction, and gravity.
  34. Physics is the most fundamental and all-inclusive of the sciences, and has had a profound effect on all scientific development. In fact, physics is the present-day equivalent of what used to be called natural philosophy, from which most of our modern sciences arose. Students of many fields find themselves studying physics because of the basic role it plays in all phenomena.
  35. Statistical mechanics, then, is the science of the phenomena of heat, or thermodynamics.
  36. 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.
  37. Thus most chemical reactions do not occur, because there is what is called an activation energy in the way. In order to add an extra atom to our chemical requires that we get it close enough that some rearrangement can occur; then it will stick. But if we cannot give it enough energy to get it close enough, it will not go to completion it will just go partway up the “hill” and back down again.
  38. Physics is of great importance in biology and other sciences for still another reason, that has to do with experimental techniques. In fact, if it were not for the great development of experimental physics, these biochemistry charts would not be known today. The reason is that the most useful tool of all for analyzing this fantastically complex system is to label the atoms which are used in the reactions.
  39. Proteins have a very interesting and simple structure. They are a series, or chain, of different amino acids. There are twenty different amino acids, and they all can combine with each other to form chains in which the backbone is CO-NH, etc. Proteins are nothing but chains of various ones of these twenty amino acids. Each of the amino acids probably serves some special purpose.
  40. 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.
  41. There is a fact, or if you wish, a law, governing all natural phenomena that are known to date. There is no known exception to this law—it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call energy, that does not change in the manifold changes which nature undergoes.
  42. In order to verify the conservation of energy, we must be careful that we have not put any in or taken any out. Second, the energy has a large number of different forms, and there is a formula for each one. These are gravitational energy, kinetic energy, heat energy, elastic energy, electrical energy, chemical energy, radiant energy, nuclear energy, mass energy. If we total up the formulas for each of these contributions, it will not change except for energy going in and out.
  43. We call the sum of the weights times the heights gravitational potential energy—the energy which an object has because of its relationship in space, relative to the earth.
  44. The general name of energy which has to do with location relative to something else is called potential energy. In this particular case, of course, we call it gravitational potential energy.
  45. Elastic energy is the formula for a spring when it is stretched. How much energy is it? If we let go, the elastic energy, as the spring passes through the equilibrium point, is converted to kinetic energy and it goes back and forth between compressing or stretching the spring and kinetic energy of motion.
  46. other conservation laws there are in physics. There are two other conservation laws which are analogous to the conservation of energy. One is called the conservation of linear momentum. The other is called the conservation of angular momentum.
  47. The laws which govern how much energy is available are called the laws of thermodynamics and involve a concept called entropy for irreversible thermodynamic processes.
  48. What is this law of gravitation? It is that every object in the universe attracts every other object with a force which for any two bodies is proportional to the mass of each and varies inversely as the square of the distance between them. This statement can be expressed mathematically by the equation
  49. Galileo discovered a very remarkable fact about motion, which was essential for understanding these laws. That is the principle of inertia—if something is moving, with nothing touching it and completely undisturbed, it will go on forever, coasting at a uniform speed in a straight line. (Why does it keep on coasting? We do not know, but that is the way it is.) Newton modified this idea, saying that the only way to change the motion of a body is to use force. If the body speeds up, a force has been applied in the direction of motion. On the other hand, if its motion is changed to a new direction, a force has been applied sideways. Newton thus added the idea that a force is needed to change the speed or the direction of motion of a body.
  50. Any great discovery of a new law is useful only if we can take more out than we put in.
  51. Why can we use mathematics to describe nature without a mechanism behind it? No one knows. We have to keep going because we find out more that way.
  52. We conclude the following: The electrons arrive in lumps, like particles, and the probability of arrival of these lumps is distributed like the distribution of intensity of a wave. It is in this sense that an electron behaves “sometimes like a particle and sometimes like a wave.”
  53. “It is impossible to design an apparatus to determine which hole the electron passes through, that will not at the same time disturb the electrons enough to destroy the interference pattern.” If an apparatus is capable of determining which hole the electron goes through, it cannot be so delicate that it does not disturb the pattern in an essential way. No one has ever found (or even thought of) a way around the uncertainty principle. So we must assume that it describes a basic characteristic of nature. The complete theory of quantum mechanics which we now use to describe atoms and, in fact, all matter depends on the correctness of the uncertainty principle.
  54. We would like to emphasize a very important difference between classical and quantum mechanics. We have been talking about the probability that an electron will arrive in a given circumstance. We have implied that in our experimental arrangement (or even in the best possible one) it would be impossible to predict exactly what would happen. We can only predict the odds!

What I got out of it

  1. A fun introductory lesson into some key physics ideas and a great view into Feynman’s thinking process

Genius: The Life and Science of Richard Feynman by James Gleick

Summary

  1. Gleick goes into the fascinating history, personality, and accomplishments of Richard P. Feynman

If you’d prefer to listen to this article, use the player below.

You can also find more of my articles in audio version at Listle

Key Takeaways

  1. Feynman was an unusually original thinker, someone with enormous horsepower who wanted to think and build from first principles – sometimes to an exaggerated degree which wasted a lot of his time and lead to many lost hours. However, this was also responsible for his intuitive leaps and orthogonal way of attacking problems
  2. Nature uses only the longest threads to weave her patterns, so each small piece of her fabric reveals the organization of the entire tapestry
  3. Feynman had a deep belief in nature, a skepticism of experts, and a distinct impatience for mediocrity
  4. To Feynman, knowledge was not something used to explain but was pragmatic, something that helped you accomplish things 
  5. He was a true Renaissance man – having had breakthroughs in physics and mathematics and enjoyed playing the drums, picking up women, learning languages, breaking into safes, and more. He was playful, idiosyncratic, independent, and had a chaotic streak in him
  6. If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis that all things are made of atoms — little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.
  7. Innovation is simply imagination straightjacketed – this was Feynman’s way of thinking through problems. He set barriers, limitations, boundaries on the problem set and then went about solving within this limitations 
  8. Feynman so thoroughly practiced formulas, integrations, and thought experiments that he developed a deep intuition for how they function and apply in the real world. People often joked that his intuition was so spot on that if he wanted to understand how an electron behaves he would simply ask himself, “If I were an electron, how would I behave?”
  9. In high school he had not solved Euclidean geometry problems by tracking proofs through a logical sequence, step by step. He had manipulated the diagrams in his mind: he anchored some points and let others float, imagined some lines as stiff rods and others as stretchable bands, and let the shapes slide until he could see what the result must be. These mental constructs flowed more freely than any real apparatus could. Now, having assimilated a corpus of physical knowledge and mathematical technique, Feynman worked the same way. The lines and vertices floating in the space of his mind now stood for complex symbols and operators. They had a recursive depth; he could focus on them and expand them into more complex expressions, made up of more complex expressions still. He could slide them and rearrange them, anchor fixed points and stretch the space in which they were embedded. Some mental operations required shifts in the frame of reference, reorientations in space and time. The perspective would change from motionlessness to steady motion to acceleration. It was said of Feynman that he had an extraordinary physical intuition, but that alone did not account for his analytic power. He melded together a sense of forces with his knowledge of the algebraic operations that represented them. The calculus, the symbols, the operators had for him almost as tangible a reality as the physical quantities on which they worked. Just as some people see numerals in color in their mind’s eye, Feynman associated colors with the abstract variables of the formulas he understood so intimately. “As I’m talking,” he once said, “I see vague pictures of Bessel functions from Jahnke and Emde’s book, with light tan j’s, slightly violet-bluish n’s, and dark brown x’s flying around. And I wonder what the hell it must look like to the students.
  10. It is not enough to be able to simply repeat, manipulate, and recall mathematical equations. A deep physical intuition of nature and reality is necessary to make the types of leaps that Feynman and Einstein made 
  11. Our knowledge of things is inextricably linked to our language and analogies. Words and phrases that we use cannot be decoupled from our knowledge
  12. Better to have a jumbled bag of tricks than one orthodox tool – imprecise shortcuts and hacks are more effective than rigid planning
  13. Feynman also had tremendous influence in a number of fields outside of particle physics including nanotechnology, genetics, molecular biology, and more. 
  14. Several different times throughout his life, Feynman tried to map his knowledge, the interconnections, and how they influence each other, creating a mental map of his understanding of his world. This would help him understand where his understanding was limited, where connections and interconnections happened, where the edge of the field and new opportunities might be.
  15. Feynman struggled for a long time to figure out which problems to work on. He rarely pursued ideas to their end, even when he was encouraged to do so and the results would likely to lead to breakthrough findings and research papers
  16. Only when you truly understand what an explanation is (not the name, but the nature) can you begin thinking about more subtle questions

What I got out of it

  1. A really enjoyable book which helped me better understand Feynman – how curious, playful, and smart he was but also his temper and his inability to follow through on many papers and experiments. What sticks with me though was how deeply he wanted to understand things – not the name, but the nature. I would also love to see how he mapped his knowledge in his journals. I think this would be a hugely beneficial process to better understand what we truly know, see how things interconnect, where we are lacking knowledge, where the opportunities might lie, etc..

What Do You Care What Other People Think? by Richard Feynman, Ralph Leighton

Summary

  1. A fun recounting of Feynman’s life, time on NASA exploring the Challenger disaster and his genuine curiosity of all things
Key Takeaways
  1. Father and first love had the biggest influence on him
  2. Father turned science and teaching into reality when he was a boy by making analogies or comparing to immediate surroundings
  3. Huge difference between knowing the name of something and knowing something
  4. Highest forms of understanding are laughing and human compassion
  5. Have no respect for authority. Question everything and if faulty conclusion, call it as you see it
  6. Science helps man’s imagination catch up to that of nature
  7. In order for any progress, we must recognize our ignorance and leave room for doubt
What I got out of it
  1. A fun read with some insight into how Feynman was as a person and thinker

Surely You’re Joking, Mr. Feynman! by Richard Feynman

Summary

  1. Richard Feynman takes us through his fun and at times eccentric life – from art and bongo drums to nuclear physics. Very enjoyable read

If you’d prefer to listen to this article, use the player below.

You can also find more of my articles in audio version at Listle

Key Takeaways  

  1. Feynman’s life told through his point of view
  2. Worked on the Manhattan project in 1943
  3. Was obsessed with radios as a young kid and figured out how to build and fix broke ones
  4. Had amazing curiosity and solved things by thinking through them before it was taught to him, even things like trigonometry. This series got him in trouble with adults since he wouldn’t simply listen and do – he actually thought and sometimes came up with better ways of doing things but he adults didn’t like that since it wasn’t their way
  5. People don’t learn by understanding, they learn by rote. Their knowledge is so fragile
  6. Put himself in uncomfortable situations a lot of the time because he was trying to figure out a better way to do things or simply learn something new
  7. People often the idea of how they felt but not the exact word or details
  8. Was able to perfectly observe his dreams and control them. He wanted to understand how we were able to see things without any outside stimulation
  9. When somebody is explaining something new to him he always comes up with examples in his mind that would fit the conditions
  10. In life you learn from your mistakes. Don’t make them again. And that’s the end of you
  11. Feynman got really into art and eventually got good enough where he had an agent and was able to sell some of them
  12. Hates arrogant fools more than anything
  13. Sees things so logically and is so curious that it causes problems often and puts him in difficult situations
  14. Wins the Nobel but doesn’t want to deal with all the hassle but ends up accepting it
  15. Becomes incredibly adept at cracking safes
  16. Simply an incredibly curious person who enjoyed solving things and being with other people. Seemed very pragmatic and disliked arrogance of any kind

  What I got out of it  

  1. Feynman’s genuine curiosity and love of life is admirable. Seems like such a carefree person who pursued his curiosity and his desire to learn and teach. He was able to explain things more simply and elegantly than most, learning deeply about things most people simply take for granted or don’t care enough to truly think about.