Why is it that the uncertainty principle is not applicable to macroscopic objects? Specifically, at which scale does the uncertainty principle does not work? And also why? Why doesn't it work for macroscopic objects?
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2It does. If you edit your question to include what you consider to be a statement of the principle, we can address your confusion. – J.G. May 28 '21 at 06:04
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1Possible duplicate: Is quantum mechanics applicable to only small things? – SG8 May 28 '21 at 06:20
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Relevant: Quantum properties of objects with zero velocity – SG8 May 28 '21 at 06:21
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Another possible duplicate: Confusion about uncertainty principle – SG8 May 28 '21 at 06:22
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1Does this answer your question? Confusion about uncertainty principle – user256872 May 28 '21 at 06:35
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1Possible duplicates: https://physics.stackexchange.com/q/241961/2451 and links therein. – Qmechanic May 28 '21 at 07:35
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First of all, it depends on what is meant by a macroscopic object. E.g., Bose-einstein condensates or a superconducting state are the examples of quantum phenomena occuring on macroscopic scale, and they do obey the uncertainty principle, such as, e.g., phase-number uncertainty relation for the supercondcuting state.
Secondly, we know of small but macroscopic objects, such as small proteins or fullerene molecules behaving as quantum object, tunneling through barriers, etc. The ucnertainty principle works here as well.
What the OP probably had in mind is the macroscopic obecets that we encounter every day, outside of a physics lab. Here the point is that they cannot be considered as a single object - due to the interactions the state of such objects is thermodynamic, i.e., the atoms/electrons/nuclei in such objects are typically localized on the length scales much smaller than the extent of the object.
The scales characterizing the lack of coherence in a macroscopic objects are thus coherence length of the particles in it (for mobile electrons it is usually known as a mean free path, which even in highest purity semiconductors is about hundreds of nanometers).
Roger V.
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