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bolshiabarmalay t1_j6yjse4 wrote

Reply to comment by Naive_Age_566 in extremely long stick additional questions? by Unnombrepls

what if your stick is at absolute zero? your molecular movement would then be stopped. would the stick finally be able to move instantaneously?

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Silver_Agocchie t1_j6ymzvu wrote

No because the energy of you pushing of the stick is still transmitted as an energy wave as described above regardless of the current state of the atoms in the stick. By adding energy with the push, the atoms of the stick will no longer be at absolute zero.

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HeraldOfNyarlathotep t1_j6yntsz wrote

Absolute zero just means there's absolutely no heat energy in the material; getting near that can cause weird things to happen in some materials, but it doesn't mean the entire object goes supernaturally rigid. (I think that's sorta what you were picturing, anyway.) Inertia and mass and such aren't changing. Causality too, given we're talking about moving light-years-long sticks instantaneously.

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bolshiabarmalay t1_j6ypw3d wrote

that's what I was picturing, I understood absolute zero to be where molecular movement stopped attaining supernatural rigidity. The last time I thought about it was highschool physics, so a very simple comprehension of the science as a whole. Interesting to think about tho, thanks for the reply.

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HeraldOfNyarlathotep t1_j6yrvpz wrote

Happy to help friend. Agreed, I love these sorts of questions. They're like logic puzzles, but figuring out the answer usually involves learning something more broadly interesting than "ah, it's that particular sequence of steps to solve it".

XKCD's What If? Articles and books are fantastic for this, if you aren't already aware of them. There's about 160 of em on his site, currently.

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Coomb t1_j783kny wrote

Even if it were true in general that at absolute zero there were no thermal motion of atoms, that wouldn't make things infinitely rigid.

When you push on something, your outer electrons are repelling the electrons of the other object (whether this repulsion happens because of the Pauli exclusion principle or electromagnetism or both is irrelevant for this reasoning).

Anything with mass, like an atom, doesn't move instantaneously when a force is applied. Instead, it accelerates. Therefore, it takes some finite amount of time to move the first layer of atoms back to their equilibrium position (i.e. how far away from your hand, or tool, or whatever, they would be if the two surfaces were just in contact). Similarly, it takes some finite amount of time to move the row of atoms, and the row after that, and the row after that. This is entirely independent of random thermal fluctuation of the atoms.

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things_will_calm_up t1_j6znrpn wrote

This is similar to asking how fast it moves if there was no time. It doesn't make much sense. If there is no molecular movement, then nothing pushes anything and force doesn't propagate.

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