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We all know that the atoms in any solid matter vibrate about their mean position but why do they do so?? What will happen if they stop vibrating??

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  • $\begingroup$ I don't know who downvoted you. But I can say that your question is not clear enough. What do you mean with "any matter" ? Solid state ? Gaseous state ? Furthermore, there is no "mean position" for a Helium atom in the gaseous state. $\endgroup$ – Maurice May 9 '20 at 10:02
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    $\begingroup$ By 'matter' I presume you mean ' molecule' In that case the motion is explained by the Heisenberg Uncertainty Principle, according to which is is not possible at the same time to measure exactly position and momentum. The limits imposed mean that there is a zero point energy in all vibrations. (By 'mean position' you should use 'centre of mass'). Bonds cannot stop vibrating. If there was a molecule with no zero point energy, we would know that quantum mechanics had failed. So far quantum mechanics has passed all the tests. $\endgroup$ – porphyrin May 9 '20 at 11:31
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    $\begingroup$ @Zenix, nothing stops vibration at absolute zero. Vibration continues, it is called zero point energy. $\endgroup$ – M. Farooq May 9 '20 at 14:11
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    $\begingroup$ @M.Farooq I didn't know that, thanks. I just guessed... $\endgroup$ – Zenix May 9 '20 at 14:41
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    $\begingroup$ They vibrate because they have kinetic energy yet are confined locally within a potential well resulting from attractive and repulsive interactions with neighboring atoms. At absolute zero quantum mechanical principles suggest that they should just keep vibrating. For more on this you might want to ask at physics SE or philosophy SE. $\endgroup$ – Buck Thorn May 9 '20 at 15:10
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I will interpret your question to mean: why must all particles vibrate? This is explained best using quantum mechanics. One of the postulates of quantum mechanics is the Heisenberg Uncertainty Principle. It means that one cannot measure both the position and momentum of a particle to arbitrary precision. This means that if one measures the momentum of a particle to greater levels of precision, the position of the particle becomes less certain and vice versa. The particle must vibrate since if it was perfectly stationary, it would be possible to determine position and momentum to greater levels possible than that allowed by the Heisenberg Uncertainty Principle.

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