# What if there was no friction?

This is a weird thought experiment, but what if there was no such thing as frictional force? Is such a universe possible? Would any large scale structure be able to hold itself together? Would planets be completely smooth? If I were on a slight incline, would I slide down to the lowest area just as fast as if I were falling?

It’d take all the fun out of sex, that’s for sure.

I don’t think it would be possible; the properties of matter that result in friction are the same properties that allow you to push something perpendicularly to its surface, or stand upright on a solid surface; on a very small scale, that#'s what’s happening with friction; protruding parts of object A ‘key’ into recessed spaces in object B (and vice versa) - sideways force pushes the edges of these parts/spaces against each other head on - when friction is overcome, the protrusions ‘cam out’ of the spaces and the two surfaces ride over each other.

If there were strictly no friction, there could in fact be no physical interaction between material objects at all (or rather no interaction between the electromagnetic fields of their atoms, which is different, but the same)

So…like friedo said.

That’s the funniest thing I’ve read all week.

But **Mangetout **got it right. Friction is not a force or effect that exists apart from other forces and effects that are fundamental to the universe as we know it.

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If there were strictly no friction, there could in fact be no physical interaction between material objects at all (or rather no interaction between the electromagnetic fields of their atoms, which is different, but the same)
I disagree. Friction is a specific kind of interaction. If you want to say there can be solid objects but they can’t have friction between them, well, they certainly can interact in other ways.

There are real physical objects whose mutual friction is small enough that it isn’t important (so it could suddenly become zero and you wouldn’t notice the difference). I think air hocky tables come close enough for starters. There could still be the force transmitted normal to the surface, there could be elastic collisions and solid objects could divert fluid movement and things could bend and flex and so forth.

Now, you might also argue that friction on the scale of molecules inside an object is what gives it shear modulus - or at least that this is the case for things that exhibit creep, like glass or lead or some polymers. So, eliminating this kind of friction turns everything into an inviscid liquid or gas (one without viscosity). Lots of fluid behaviors are practically inviscid anyway. Generally speaking, large movements like weather and ocean currents are pretty inviscid, especially if they are rapid.

We have names like “friction” to use when we are focussed on what we’d consider a group or class of phenomena, but the world is all so interconnected that it’s hard to imagine turning friction off. Nature doesn’t know it is doing one specific thing when it is carrying out what we perceive as friction. There’s no switch for just friction, you might say.

But really eliminating friction would involve getting rid of things that may be needed for anything to exist at all:
Quantum vacuum friction (Paul Davies)

I don’t think so; this is what I’m talking about - the properties of materials that prevent them simply passing through each other are the same properties that make friction happen - on a small enough scale, that’s what bits of object A are doing to object B - trying to pass through each other, and failing.

Sure, but those are specific examples of friction being reduced by minimising the interaction between the objects - that’s not what the OP was asking about.

This is more or less what I said. So you do agree?