4 ms·

Feynman's fascination with basically everything is always so fun. Here is another, where he is talking about trying to figure out why ice is slippery... https:

Feynman's fascination with basically everything is always so fun. Here is another, where he is talking about trying to figure out why ice is slippery... https://newsletter.butwhatfor.com/p/takeaway-tuesday-richard-feynman https://newsletter.butwhatfor.com/p/takeaway-tuesday-richard... Copy / Paste: "But the problem, you see, when you ask why something happens, how does a person answer why something happens? For example, Aunt Minnie is in the hospital. Why? Because she went out, slipped on the ice, and broke her hip. That satisfies people. It satisfies, but it wouldn't satisfy someone who came from another planet and who knew nothing about why when you break your hip do you go to the hospital… And you begin to get a very interesting understanding of the world and all its complications. If you try to follow anything up, you go deeper and deeper in various directions. For example, if you go, “Why did she slip on the ice?” Well, ice is slippery. Everybody knows that, no problem. But you ask why is ice slippery? That’s kinda curious. Ice is extremely slippery. It's very interesting. You say, how does it work? You could either say, “I’m satisfied that you’ve answered me. Ice is slippery; that explains it,” or you could go on and say, “Why is ice slippery?” and then you're involved with something, because there aren't many things as slippery as ice... A solid that’s so slippery? Because it is, in the case of ice, when you stand on it (they say) momentarily the pressure melts the ice a little bit so you get a sort of instantaneous water surface on which you're slipping. Why on ice and not on other things? Because water expands when it freezes, so the pressure tries to undo the expansion and melts it. It's capable of melting, but other substances get cracked when they're freezing, and when you push them they're satisfied to be solid. Why does water expand when it freezes and other substances don’t? I’m not answering your question, but I'm telling you how difficult the why question is. You have to know what it is that you're permitted to understand and allow to be understood and known, and what it is you're not. You'll notice, in this example, that the more I ask why, the deeper a thing is, the more interesting it gets. We could even go further and say, “Why did she fall down when she slipped?” It has to do with gravity, involves all the planets and everything else. Nevermind! It goes on and on."

dr_dshiv 5y ago
And yet he totally shuts down the question of why positive and negative charges attract… which I’ve always been dying to understand. https://www.physicsforums.com/threads/why-do-positive-and-negative-charges-attract.401974/ https://www.physicsforums.com/threads/why-do-positive-and-ne...
- amelius 5y ago
  Change your reference frame. Assume both charges are moving at constant speed != 0 in the same direction. From this view they are not charges but opposite currents. We know that opposite currents repel [1]. Therefore, one could conclude that opposite charges repel. It's this kind of question that the interviewer should ask. [1] https://www.quora.com/Why-do-two-wires-with-current-flowing-in-the-same-direction-attract-each-other-and-two-wires-with-current-flowing-in-opposite-direction-repel https://www.quora.com/Why-do-two-wires-with-current-flowing-...
- rrss 5y ago
  The difficulty is that eventually you reach a level where there are no satisfying answers to this sort of question. There are a lot of interesting levels to explore between “why did aunt Minnie go to the hospital” and fundamental physical principles, but for things like “why do magnets repel?” (or “why do unlike charges attract?”), these questions are getting pretty close to the point where the only answer is “we don’t know, that’s just what we see happens when we watch the universe work.” You can go farther and get stuff about the action in quantum electrodynamics, but these don’t really provide any more satisfying answers, they just lead to more questions like “why do systems follow trajectories of stationary action?” and “why is the lagrangian for electromagnetism what it is?”
  - Cleonis 5y ago
    You mention stationary action. Interestingly, F=ma and Hamilton's stationary action are mutually derivable. The usual presentation is to show that Hamilton's stationary action implies the newtonian formulation. Interestingly, it is also possible to start with F=ma, and move in all forward steps to Hamilton's stationary action. No additional assumptions are required. I created a series of interactive diagrams to make Hamilton's stationary action entirely transparent. http://www.cleonis.nl/physics/phys256/energy_position_equation.php http://www.cleonis.nl/physics/phys256/energy_position_equati... (Of course, quantum mechanics is the overall deeper theory; we assume that classical mechanics holds good because classical mechanics is a limiting case of quantum mechanics; at scales large enough that quantum effects average out the outcome in terms of quantum mechanics converges onto the outcome in terms of classical mechanics.)
GDC7 5y ago
> Feynman's fascination with basically everything is always so fun. Here is another, where he is talking about trying to figure out why ice is slippery... He never looks bored, many people of his level of intellect only have very short moment of real hype when they actually have big wins and are proven right and recognized by peers (Nobel prize, Fields medal...) Feynman has such a wide interests , also things which people even on here would consider mundane and not special enough to be given the time of the day such as bongos, painting as a hobby, dancing at the Rio Carnival, stripclubs, strippers and sex workers. Also Tuva which is a territory forgotten by god himself as well as men.

dr_dshiv 5y ago

And yet he totally shuts down the question of why positive and negative charges attract… which I’ve always been dying to understand. https://www.physicsforums.com/threads/why-do-positive-and-negative-charges-attract.401974/ https://www.physicsforums.com/threads/why-do-positive-and-ne...

amelius 5y ago
Change your reference frame. Assume both charges are moving at constant speed != 0 in the same direction. From this view they are not charges but opposite currents. We know that opposite currents repel [1]. Therefore, one could conclude that opposite charges repel. It's this kind of question that the interviewer should ask. [1] https://www.quora.com/Why-do-two-wires-with-current-flowing-in-the-same-direction-attract-each-other-and-two-wires-with-current-flowing-in-opposite-direction-repel https://www.quora.com/Why-do-two-wires-with-current-flowing-...
rrss 5y ago
The difficulty is that eventually you reach a level where there are no satisfying answers to this sort of question. There are a lot of interesting levels to explore between “why did aunt Minnie go to the hospital” and fundamental physical principles, but for things like “why do magnets repel?” (or “why do unlike charges attract?”), these questions are getting pretty close to the point where the only answer is “we don’t know, that’s just what we see happens when we watch the universe work.” You can go farther and get stuff about the action in quantum electrodynamics, but these don’t really provide any more satisfying answers, they just lead to more questions like “why do systems follow trajectories of stationary action?” and “why is the lagrangian for electromagnetism what it is?”
- Cleonis 5y ago
  You mention stationary action. Interestingly, F=ma and Hamilton's stationary action are mutually derivable. The usual presentation is to show that Hamilton's stationary action implies the newtonian formulation. Interestingly, it is also possible to start with F=ma, and move in all forward steps to Hamilton's stationary action. No additional assumptions are required. I created a series of interactive diagrams to make Hamilton's stationary action entirely transparent. http://www.cleonis.nl/physics/phys256/energy_position_equation.php http://www.cleonis.nl/physics/phys256/energy_position_equati... (Of course, quantum mechanics is the overall deeper theory; we assume that classical mechanics holds good because classical mechanics is a limiting case of quantum mechanics; at scales large enough that quantum effects average out the outcome in terms of quantum mechanics converges onto the outcome in terms of classical mechanics.)

GDC7 5y ago

> Feynman's fascination with basically everything is always so fun. Here is another, where he is talking about trying to figure out why ice is slippery... He never looks bored, many people of his level of intellect only have very short moment of real hype when they actually have big wins and are proven right and recognized by peers (Nobel prize, Fields medal...) Feynman has such a wide interests , also things which people even on here would consider mundane and not special enough to be given the time of the day such as bongos, painting as a hobby, dancing at the Rio Carnival, stripclubs, strippers and sex workers. Also Tuva which is a territory forgotten by god himself as well as men.