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Regarding "fully" understanding physics, I like to refer people to Feynman's answer to a question about why magnets repel each other[0]. "Assuming something" i

• agumonkey 7y ago
  I'd love to have others high grade researcher pitch in about the art of good theory. Often it's more a matter of disregarding your own perceptions, and aim for the out-of-the-box stupid.
• foldr 7y ago
  I've never really been that impressed with Feynman's responses in that interview. He seems to be uncomfortable with just saying that physicists don't really know on a fundamental level why magnets repel each other. Obviously, explanations can be more or less fundamental.
  • Swizec 7y ago
    Didn’t his answer boil down to “The math is the physics. That’s the explanation. That’s how it works. You can’t just make up an analogy because the math is the analogy”
    • foldr 7y ago
      That seems a bit extreme and not really consistent with the attitude he took in his public lectures and in Surely You're Joking. It amounts to giving up and saying that you can't explain basic physical phenomena to laypeople on any level.
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  • tsbinz 7y ago
    He's trying to get the point across that "X don't really know on a fundamental level why X" for any group of people X and observation Y, if by "on a fundamental level" you mean "is not based on something assumed to be true". He's not uncomfortable with it, anyone with a scientific or engineering background knows that (or at least should know that). That doesn't stop predictions obtained from well-tested models from being useful.
    • foldr 7y ago
      Well, maybe that's what he's trying to get across, but it seems largely irrelevant to the interviewer's question. He could just have given a physics textbook level explanation of how magnets work. I'm not convinced that there's some kind of profound misunderstanding evident in the interviewer's question that needs addressing in long and rambling terms.
      • peignoir 7y ago
        I love this interview it’s typical of Feynman; what do you mean by how magnet works is a fair question but it’s also a multi form one. We don’t really know we just know up to a certain level he had a lecture about how Mayans predicted astronomical events with beans, were the bean the answer to why?. I’ve learned a lot from this interview on how to look at science. Why is indeed a profound concept
      • d0mine 7y ago
        There is actually a subtle point on why the question of "physicists don't really know on a fundamental level why magnets repel each other" is nonsense ultimately which doesn't stop physics from producing useful or interesting in some other way models. Those who think that a textbook explanation could have been the answer are missing the point: it is not about magnets—it is about what it means to know anything in terms of anything else. There is no need for useful models to form a nested hierarchy converging to a single "reality" i.e., it is not necessary for a model to be more fundamental than another model even if they relate to what we observe as the same phenomenon.
        • 7y ago
  • andrewon 7y ago
    I actually think his explanation is right on. Physicists are practical. They make model to quantitatively describe their experiments. Understanding fundamental truth is kind of a by-product. They generally follows a reductionist approach, so a simpler model that can explain a wider set of experiments is a better model. But there's no guarantee that a simpler explanation is the "truth". All we can say is this approach "makes sense".
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  • Steuard 7y ago
    The odd thing is, we physicists actually have a pretty solid understanding of why magnets repel each other. It's a fun story, one that I try to include every time I teach the subject, and I'm pretty sure that Feynman knew it! So it's curious to me to see Feynman basically dodging this question. (His point that "I can't explain it in terms of anything else you're already familiar with" is entirely valid! But I kinda feel like that's what questions are for: learning new things, that we may not already be familiar with.) With that in mind, I probably would have answered in a different way, though the questioner might get bored and regret asking if I didn't find a way to be unusually efficient about it: this answer relies on a lot of knowledge that seems at best tangentially related. :) I'd try to give some rough description of the way that moving currents generate magnetic fields (especially the field generated by a current loop), and the way that moving currents feel a force due to magnetic fields (especially the force on a current loop). That's enough to argue that current loops will interact with each other in just the same ways that magnets do. And then I could tell at least a sketch of the story of how regions of aligned spins in magnetic materials act on average like current loops. (But that's quite a long story to answer a simple question, so again, I can sympathize with Feynman for saying, "There isn't a straightforward answer that a non-expert would understand.")
    • jjdredd 7y ago
      I don't think you understand the issue here. He's not dodging the question. On the contrary, he's answering on the most fundamental level.
  • archgoon 7y ago
    > Obviously, explanations can be more or less fundamental. That's not obvious, in fact, it's not even true. Feynman's point is that people bring context to a question. People will accept different things as 'fundamental'; different assumptions and axioms. Can you sometimes explain things using fewer axioms? Sometimes; but is it more fundamental? Is it better to build a theory on fewer axioms, even if they can't be directly validated? Would you prefer a theory based on 4 axioms, none of which can be directly validated, over one with 6, but you can measure all six directly? What if the four can't be re-derived from the 6, but all observable statements can? What if either set can be re-derived from the other? Feynman isn't saying that "physicists don't really know on a fundamental level why magnets repel each other". He's alluding to the idea that that question isn't well defined. He's encouraging the questioner to figure out what sort of answer would satisfy them, and why.
    • foldr 7y ago
      I think it's obviously true that some explanations are more fundamental than others. We have, e.g. a more fundamental explanation of tides than anyone did in 500AD. That is not to deny that it is difficult to make precise what exactly it is that makes one explanation more 'fundamental' than another. As always, individual cases are clear; the general principle is elusive. >He's alluding to the idea that that question isn't well defined. It's well-defined enough to answer. Hundreds of millions of school children learn a perfectly sensible answer to the question every year. (Would this answer satisfy someone with a PhD in physics? Obviously not. But that's not the point.) It's in any case bizarre to insist that a layperson ask a question that's well-defined according to the standards of a particular field.