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It became widely accepted that quantum effects don't show up in macroscopic objects due to the process of decoherence, in which the interaction with the enormous number of degrees of freedom of the environment destroys, or hides, the quantum effects. However, everything around us is made up of atoms and molecules, which are full of quantum phenomena. How are these phenomena protected from decoherence ?

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The energy difference in the environmental probes are typically less than the energy gap in the spectrum of the atoms and molecules. Decoherence still happens, but the pointer states are now energy eigenstates. This is such an important point. It's not that there is no decoherence. Rather, the pointer states are not position wavepackets.

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Is there a proof that the pointer states are energy eigenstates? – Tarek Jul 29 '12 at 11:17

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