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Think of it this way - decoherence depends on regions of the wave function more or less becoming isolated from one another in such a way that the results of exp

Think of it this way - decoherence depends on regions of the wave function more or less becoming isolated from one another in such a way that the results of experiments for classical things in those regions match our results. The wave function is still fundamental, but classical physics emerges as a limit. The problem with decoherence is that the underlying physics of the wave function is still profoundly non-local in the sense that regions of the wave function don't have a simple relationship with regions of physical space. And yet, classically, the notion of locality pertains precisely to physical space and is deeply related to fundamental physics. In fact, locality is still fundamental to the formulation of quantum mechanical theories, even if the quantum mechanical description ends up having some non-local features. And there isn't any philosophical or physical intuition that resolves this disconnect. Decoherence has a variety of other philosophical issues. In particular, it requires that we accept the idea of the wave function (something we never see or interact with directly, for which we have no direct evidence) as fundamental and real AND that we take our day to day experiences, upon which all of our physical sciences are based, as derived, perhaps even, in important ways, not really real. In any case, the actual theoretical terms in which decoherence actually resolves the measurement paradox aren't fully understood either mathematically or in terms of the fundamental ontological status of things.

remcob 7y ago
Thank you for this very well articulated response. I don't see why locality is a requirement. What is it that makes a theory with particles being points in a six-dimensional position-momentum space acceptable, but particles being complex-valued functions over a three dimensional space unacceptable? > it requires that we accept the idea of the wave function (something we never see or interact with directly, for which we have no direct evidence) as fundamental and real AND that we take our day to day experiences, upon which all of our physical sciences are based, as derived, perhaps even, in important ways, not really real. I see no issue in pure quantum states being fundamental. Our day to day experiences are not compatible with a number of things we hold to be true. Take the physics of fluids for example, it suggests that liquids are infinitely dividable, which we know to be false. In that sense, fluid physics is decidedly not real. But it can also be derived as a very good approximation of the underlying reality on larger scales, similarly to how classical theories are good approximations of the underlying quantum reality on larger scales. I do realize that my interpretation requires decoherence to work such that the pure quantum states reduce to ones that are well approximated by classical theories, and I'm not sure if we have evidence that decoherence works this way.

remcob 7y ago

Thank you for this very well articulated response. I don't see why locality is a requirement. What is it that makes a theory with particles being points in a six-dimensional position-momentum space acceptable, but particles being complex-valued functions over a three dimensional space unacceptable? > it requires that we accept the idea of the wave function (something we never see or interact with directly, for which we have no direct evidence) as fundamental and real AND that we take our day to day experiences, upon which all of our physical sciences are based, as derived, perhaps even, in important ways, not really real. I see no issue in pure quantum states being fundamental. Our day to day experiences are not compatible with a number of things we hold to be true. Take the physics of fluids for example, it suggests that liquids are infinitely dividable, which we know to be false. In that sense, fluid physics is decidedly not real. But it can also be derived as a very good approximation of the underlying reality on larger scales, similarly to how classical theories are good approximations of the underlying quantum reality on larger scales. I do realize that my interpretation requires decoherence to work such that the pure quantum states reduce to ones that are well approximated by classical theories, and I'm not sure if we have evidence that decoherence works this way.