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Magnets If you get hold of two magnets and you push them you can feel this pushing between them, turn around the other way and they slam together. Now, what is it? The feeling between those two magnets What do you mean, what's the feeling between the two magnets... It's something there, isn't it. I mean, the sensation is there's something there when you push those two magnets together. Listen to my question, what is the meaning, when you say that there is a feeling. Of course you feel that but what do you want to know? What I want to know is what's going on... The magnets repell each other. ...between those two bits of metal? Well then, what does that mean or why are they doing that or how are they doing that? You ask... I am not saying... I think that's a perfectly reasonable question. Of course that is rearsonable, that's excellent question, OK. But the problem that you're asking you see when you ask why something happens. How does a person answer why something happens? For example... Aunt Minnie is in a hospital, why? Because she went out, she slipped on the ice and broke her hip. That satisfies people. It satisfies but it wouldn't satisfy someone who came from another planet knew nothing about things and the first is understand why when you break your hip you go to the hospital? How do you get to the hospital when the hip is broken? Well, because your husband seeing that you had the hip broken called the hospital up and sent somebody to get her. All that is understood by people. Now, when you 're explaining a "WHY", you have to be in some framework that you allow something to be true. Otherwise you're perpetually asking why. Why did the husband call up the hospital? Because husband is interested in his wife's welfare. Not always, some husbands aren't interested in their wives' welfare, they're drunk and they're angry. So you're beginning to get a very interesting understanding of the world and all it's complications. In order to try to follow anything up you go deeper and deeper in various directions. For example: 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 kind of curious. Ice is extremly slippery, it's very interesting. You say how does it work? You see, you could either say, I am 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. It's very hard to get. Greasy stuff, but that's sort of wet and slimy, but a solid that's so slippery? Because it is in the case of ice that when you stand on it they say mometarily the pessure melts the ice a little bit so you get a sort of instantenious water surface on which you're slipping. Why on ice and not on other things? Because ice expands when, water expands when it freezes so the pressure tries to undo the expansion and melts it. It's capable of melting it, but other substances contract when they're freezing and when you push them they're just satisfied to be solid. Why does water expand when it freezes and other substances don't expand when they freeze? All right? 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 are permitted to understand and allow to be understood you're knowing and what it is you're not. You noticed in this example the more I ask why its gets interesting afterwards - my idea is the deeper the thing is the more interesting and we can even go further and say why did she fall down when she slipped ? That has to do with gravity and involves all the planets and everything else. Never mind it goes on and on. Now when you ask for example why two magnets repell, there are many different levels it depends on whether you are a student of physics or an ordinary person who doesn't know anything about. If you're somebody who doesn't know anything at all about it, all I can say is that magnetic force makes them repell and that you're feeling that force. That's very strange because I don't feel kind of force like that in other circumstances. When you turn them other way they attract. There is a very analogous force, electrical force which is same kind of a question. That's also very weird. But you are not at all disturbed by the fact that when you put yor hand on the chair it pushes you back But we found out by looking at it that that's the same force as a matter of fact the electrical force not magnetic exactly in that case. But the same electrical repulsions that are involved and keeping your finger away from the chair because everything's made out of... it's electrical forces in minor in microscopic details. There are other forces involved but it is connected to electrical force. It turns out that the magnetic and the electric force with which I wish to explain these things this repulsion in the first place is what ultimately is the deeper thing that we have to start ... we can start with to explain many other things that look like they were... everybody were just accept them. You know you can't put your hand through the chair. Thats taken for granted but that you can't put your hand through the chair when looked at more closely - why? That involves these same repulsive forces that appear in magnets. The situation you then have to explain is why at magnets it goes over bigger distance than ordinarily? And there it has to do with the fact that in iron all the electrons are spinning in the same direction they all get lined up and they magnify the effect of the force until it's large enough at a distance that you can feel it. But it's a force which is present all the time and very common and it's a basic force, almost I mean I can go little further back if I were more technical but in early level I 'll just have to tell you that's going to be one of the things you'll just have to take as an element of the world the exictence of magnetic repulsion or electrical or electrical attraction, magnetic attraction. I can't explain that attraction in terms of anything else that's familiar to you. For example if we say that magnets attract like as if they were connected by rubber bands I would be cheating you because they are not connected by rubbber bands. I should be in trouble. You soon ask me about the nature of the bands. And secondly if you are curious enough you ask me why rubber bands tend to pull back together again and I would end up explaining that in terms of electrical forces, which is the very thing that I'm trying to use the rubber bands to explain. So I've cheated very badly you see. So I'm not going to be able to give you an answer to: Why magnets attract each other? Except that I tell you that they do and I tell you that that's one of the elements in the world of the different kinds of forces. There are electrical forces, magnetic forces and gravitational forces and others. And those are some of the parts. If you were the student I could go further and I could tell you that magnetic forces are related to electrical forces very intimately. That relationship between garavity forces and electrical forces remains unknown and so on. But I really can't do a good job, any job of explaining magnetic force in terms of something else that you're more familiar with because I don't understand that in terms of anyting else that you're more familiar with.

Video Details

Duration: 7 minutes and 32 seconds
Country: United States
Language: English
Genre: None
Views: 1,945
Posted by: jnpvr on Dec 23, 2010

Richard Feynman räägib, miks magnetid tõmbuvad ja miks see ei ole lihtne küsimus.

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