On 6/12/2018 6:57 PM, Lawrence Crowell wrote:
On Tuesday, June 12, 2018 at 7:05:34 PM UTC-5, Bruce wrote: From: <agrays...@gmail.com <javascript:>>* So if one chooses a basis where the cat is simultaneously alive and dead, is this a problem for QM? AG *No problem for QM -- one does it all the time. It might not be the most useful basis, but that doesn't mean it isn't possible. In general, however, one has a 'preferred basis'; a basis which is stable against environmental decoherence -- the one corresponding to what one actually sees in the laboratory. BruceThe basis that is stable against environmental quantum noise has energy eigenvalues. Energy is tied to entropy and information. Bases such as for angle (Stern Gerlach measurements etc) or angular momentum without breaking the SO(3) symmetry so Bessel functions --> Legendre functions and L_z defines energy have no such einselection property.
An isolated system has energy eigenvalues. But any realistic macroscopic system is only going to conserve energy approximately. I think energy eigenvalues are found in atoms and maybe molecules. But larger systems (C60 Bucky balls?) tend to emit and absorb photons that localize them in a position basis.
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