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<blockquote data-quote="AbdulAlhazred" data-source="post: 9323820" data-attributes="member: 82106">It is actually a variety of things, but the non-smoothness part is pretty straightforward. Suppose you take 2 pieces of sandpaper and rub them together, the little rough bits on each one will catch on each other and it will be hard to do. That's the most common sort of surface friction, two plane surfaces which contact each other resist relative motion because bits of each one catch on the other. At some level THAT happens because bits of solid matter cannot move through one another. THAT is almost certainly due to electrostatic repulsion between atoms, coupled with the fact that atoms in a solid are not free to move around, so they just get stuck. There ARE other factors, like if you have some very smooth, clean, metal plane surfaces they can actually BOND, and then you will definitely get friction! In this case it is just &quot;well, you're trying to tear apart a single chunk of a solid material, it has a sheer strength.&quot; There may also be some other, less well understood, factors at work. The real problem with the 'getting rid of friction' idea as a concept is that friction arises as out of a complex set of factors that relate to deep parts of physical laws. To 'get rid' of it, in any realistic analysis, would require profound alterations to the nature of matter. It would SURELY require changing the electromagnetic force in ways that would basically break all of chemistry, and maybe some important parts of nuclear physics as well. I'm not at all sure you can have atoms without friction being a thing! I'm even more unsure that you could have molecules and no friction, and at that point you certainly don't have living things anymore. So a realistic rendition of 'no friction' is 'poof, the lights go out, nothing exists'.</blockquote>

[QUOTE="AbdulAlhazred, post: 9323820, member: 82106"] It is actually a variety of things, but the non-smoothness part is pretty straightforward. Suppose you take 2 pieces of sandpaper and rub them together, the little rough bits on each one will catch on each other and it will be hard to do. That's the most common sort of surface friction, two plane surfaces which contact each other resist relative motion because bits of each one catch on the other. At some level THAT happens because bits of solid matter cannot move through one another. THAT is almost certainly due to electrostatic repulsion between atoms, coupled with the fact that atoms in a solid are not free to move around, so they just get stuck. There ARE other factors, like if you have some very smooth, clean, metal plane surfaces they can actually BOND, and then you will definitely get friction! In this case it is just "well, you're trying to tear apart a single chunk of a solid material, it has a sheer strength." There may also be some other, less well understood, factors at work. The real problem with the 'getting rid of friction' idea as a concept is that friction arises as out of a complex set of factors that relate to deep parts of physical laws. To 'get rid' of it, in any realistic analysis, would require profound alterations to the nature of matter. It would SURELY require changing the electromagnetic force in ways that would basically break all of chemistry, and maybe some important parts of nuclear physics as well. I'm not at all sure you can have atoms without friction being a thing! I'm even more unsure that you could have molecules and no friction, and at that point you certainly don't have living things anymore. So a realistic rendition of 'no friction' is 'poof, the lights go out, nothing exists'. [/QUOTE]

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