Richard Feynman: The Character of Physical Law

1964, Science  -   30 Comments

Probably this is one of the oldest films posted at TDF. The Character of Physical Law are a series of seven lectures by physicist Richard Feynman concerning the nature of the laws of physics.

The talks were delivered by Feynman in 1964 at Cornell University, as part of the Messenger Lectures series. Their text was published by the BBC in 1965 in a book by the same name.

The lectures covered the following topics: The law of gravitation - an example of physical law, The relation of mathematics to physics, The great conservation principles, Symmetry in physical law, The distinction of past and future, Probability and uncertainty - the quantum mechanical view of nature, and Seeking new laws.

Ratings: 9.10/10from 88 users.

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30 Comments / User Reviews

  1. Alex

    Gravity= constant *mass*Mass/distance squared?

    1. gwhosubex


  2. Quang Nguyen

    Richrad Feynman was one of the greatest teachers and physicists of all times. Althought I just knew him throught his books, videos...but "I did love the man this side idolatry as much as any"

    These lectures are too amazing. Feynman showed me the beauty of physics and made me love physics. After I had seen this wondergul lectures, I wished I could go back to the past and become a physical undergraduate student.

    1. Matt champion

      you can i did

  3. Xercès Des Stèles

    very interesting, reminds me of my astronomy classes 101 and 201 :P they should teach this at elementary schools.

    did everyone talked like mobsters, in the 60s?

  4. Vic Demise

    Yeah. You can find better diagrams that at least suggest the principle more accurately. Think of it like a pendulum which always swings at the same rate of oscillation despite the distance of the swing (long or short).
    I hope that made sense.

  5. derekbolton

    I felt his exposition of equal areas in equal intervals of time (20 minutes into 2nd lecture) would leave many puzzled. The triangle he ends up with is clearly smaller than the one he started with, and, correspondingly, the lines he declares to be parallel clearly are not.
    The explanation is that the lines are so nearly parallel, for a small interval of time, that the difference in areas is of "second-order" magnitude. I.e. as the time intervals considered are reduced, the difference in area gets smaller very much faster (as the square of the time interval). This is a calculus argument, and glossing over it is not helpful.

    1. OldRed Ned

      No. The reason for the 'puzzle' is you are looking at a free-hand drawing on the blackboard. An accurate construction of the ellipse and triangles would demonstrate the accuracy of 'equal time, equal area' argument.

  6. dave.eggermont

    probably the most educational documentary, thanks a lot for posting Vlatko

  7. W_Ali

    It seems that the photons are simply just energy waves that exist all around us with infinite possibilities to go anywhere anyhow. But when we project/expect a certain outcome from them, wether they go left or right, they will do what exactly that. Metaphorically, we have infinite possibilities to do/be whatever and whoever we want, but the possibility that we choose to focus on, is the possibility we will experience. In simpler words, everything is possible, you just have to choose what you want. :)

    1. wald0

      As of yet no one knows the mechanism by which the particle goes this way or that, only that they do go a definite direction once you look at them. That doesn't mean we psychopathically tell them where to go at all. It merely means that we have no way of observing something so small without effecting the way it behaves.

      "...photons are simply just energy waves that exist all around us..."

      Photons have a source and act in predictable ways, they do not exist mysteriousely all around us. They act both as a particle and a wave, depending on outside physical forces that act upon them. Part six of this doc explains that in very certain terms. Its nothing magical or some psychological force projected by humans, just a physical interaction between the photon being observed and the mechanism by which we observe it.

      "...when we project/expect a certain outcome from them, wether they go left or right, they will do what exactly that."

      No, they don't. That's the whole point, they do things we DONT expect or predict intuitively. Come on guys, stop trying to combine good science with psuedo scientific spirituality. I cling to science and mathematics to get away from that kind of thinking. The people that have dedicated thier lives to this stuff, the ones that gave us this knowledge, made a conciouse effort to stay away from that kind of thinking. Thats how they were able to discover these truths. If we look at them in a psuedo scientific light, if we romanticize them, we will never be able to stand on this knowledge in order to reach the next set of truths. Quantum mechanics is unintuitive, very hard to understand, exciting, refreshing, etc. but it is not magical or mysterious- no science is.

    2. Hodd

      Feel free to continue getting away from that kind of thinking, but allow others to think what they will. I see it as a positive thing, and it seems more people than ever are into science. It beats simply obeying doctrine no?

      "If we look at them in a psuedo scientific light, if we romanticize them, we will never be able to stand on this knowledge in order to reach the next set of truths."

      How so? The math speaks for itself does it not? It strikes me as normal to romanticize our scientific understandings, some of the greatest scientists did that for us.

      "Quantum mechanics is unintuitive, very hard to understand, exciting, refreshing, etc. but it is not magical or mysterious- no science is."

      To say something is magical or mysterious is to say just that... it's not understood and exciting or interesting.

      It's all perspective I guess.

    3. Achems_Razor

      What you are probably referring to is the same as "if a tree falls in the forest, does it make a sound if no one is there to hear it?"

      It depends if you are talking about a tree in a Newtonian forest or a Quantum forest.

      In a Newtonian forest, the tree will fall and sound waves will propagate regardless of, if there is someone to hear it or not. They are simply part of a chain of casual events.

      In a Quantum forest, if there is truly no one to listen to the event, and it is a closed system, then the tree is in a superposition state of both having fallen and not fallen.

      Once an observer enters the forest and opens the system to observation, the superposition of the tree will collapse, the tree will either be fallen or not fallen, and evidence of the fallen/not fallen state will be apparent throughout the system, including any evidence of propagation of sound waves... Re: Schrodinger's cat.

    4. wald0

      The theory of multiple universes solves this paradox. The cat may be alive and dead in seperate universes at the same time but, never in the same universe at the same time. Personally, I think we will eventually find we look at this whole senario in the wrong way and thats why we get this logical paradox. I don't claim to know a way to explain it and avoid the paradox without envoking multiple universes, but I think some day someone will. Then again mathematics predicts other demensions that we obviousely cannot interact with in any way- and the fractal nature of reality also suggests splintered universes- so maybe the multiple universe theory is correct. Who knows, cosmology is a bit above my pay grade, but I enjoy trying to understand it.

  8. Arnold E. Karr

    No sound on lecture 3

    1. wald0

      I noticed several segments didn't have sound as well. Very disappointing, I wanted to watch them all. Does anyone know somewhere to watch them all with sound, or maybe its the master thats bad? That would be typical, but still frustrating. We should work harder to protect things like this if that is the case.

    2. Vlatko

      That is fixed. All the lectures have sound now.

  9. Achems_Razor

    Feynman was a great physicist, "quantum mechanics" Feynman demonstrated that subatomic particles traverse infinite paths through spacetime, implicating infinite histories for any one particle.

    In other words, subatomic particles can be in more than one place at the same time. Part of "many worlds theory."

    1. Guest

      and anything a particle can do so can human.

    2. wald0

      If you watch part six Feynman explains why thats not so, in my opinion. Or maybe I misunderstood your implications, can you explain further please?

    3. Guest

      The world is a people's dream, it is a mirror of our possibilities. We still have a way to go before we can comprehend our senses and "why" they are.
      Feynman's "part six" comprehension of the mystery of life is from 1964.
      I may be wrong...i may be right or somewhere in the middle.

    4. Arnold E. Karr

      Most of those paths would require the particles to travel faster than light. How is that possible?

    5. Achems_Razor

      In the quantum world, time, the speed of light, stands still, is static. In the quantum world everything that did or could or will possibly happen in our universe and all possible parallel universes already has happened. According to theoretical physicists time, space, (spacetime), is illusion, we humans are the ones that give it a name.

      "Quantum entanglement" is instant, faster than speed of light.
      easier for you to google that for more info.

  10. wald0

    Great doc. Feynman has always been one of my favorite people to listen to. What I don't understand is how people can watch something like this and then turn around and say math is just man made and doesn't truly describe the universe. Of course mathematical symbols are man made but, they are only symbols that represent actualities in the physical world. You can call one anything you like but, all you have done is change the symbol. Like Shakespeare told us, changing the name of a rose doesn't change its properties. Mathematics is a way to relate one thing to another, a language that allows us to describe the properties of the universe we live in. The way we know we have the rules of the language correct is that the logical progression of mathematics predicts the physical realities we observe around us everyday.

    The issue we now face is that our mathematics has predicted things we are unable to measure or observe correctly, things that seem very unintuitive to our relative experience of reality. We have been able to make some observations that back up these weird findings, but they are some what complicated and ambigous. This is why, in my opinion, we have so many people that still refuse to believe in relativity much less quantum mechanics.

    That said these same people will often buy into stuff like the electrical universe, ancient aliens, or some religious interpretation of reality, which is even more counter intuitive and has no proof what so ever to back it up. So, I don't get it really. The very things they say they require of relativity or quantum mechanics in order to believe them are lacking to a much greater extent in the things they profess to believe. I am not passing judgement when I say this, only saying I don't understand.

  11. Raj Sundaram

    Absolutely fantastic

  12. MomOnEarth

    ..... sigh..... the perfect man.......

  13. Matt Kukowski

    Welcome to Feynman. You guys should Google all his videos. He is all that and MORE. Married a dieing woman (compassion), had extra-marital affairs with his students (horny), visited strip clubs (party nerd), learned to draw very well with pencil (artist), played the Bongo drums (musician), was the first to talk about NANO science (innovator) and investigated the challenger shuttle disaster (found truth in a sea of bureaucratic fools). He really is a remarkable human being. Just Lovely. :)

  14. lievesley

    awesome story teller...he makes it sound easy...awesome

  15. leonardobdas

    richard feynman is a fantastic speaker, to me the best....but I wonder....when will tim minchin will get some inspiration and do some physics lectures?

  16. BitStream


    I've heard so much about Richard Feynman over the years but haven't, until now, gotten to hear and see him. He is a fabulous lecturer.

    Thank you for this lecture series. I am going to enjoy every minute!