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Is the time of the collapse of the wave function empirical?

Suppose there is a very long von Neumann chain of observations of a quantum system. Suppose also practically irreversible decoherence happens very early along the chain. We can have an entire class of models parameterized by the point along the chain past the point of irreversible decoherence where the wave function "actually" collapses. Can we distinguish between these models empirically?

Is it even possible to push this point to the future of Jan 2013 so that as of Jan 2013, we are still in an uncollapsed superposition?

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According to Schlosshauer's analysis of experimental data:

"(i) the universal validity of unitary dynamics and the superposition principle has been confirmed far into the mesoscopic and macroscopic realm in all experiments conducted thus far;

(ii) all observed ‘‘restrictions’’ can be correctly and completely accounted for by taking into account environmental decoherence effects;

(iii) no positive experimental evidence exists for physical state-vector collapse;

(iv) the perception of single ‘‘outcomes’’ is likely to be explainable through decoherence effects in the neuronal apparatus."

(M. Schlosshauer, Annals of Physics, 321 (2006) 112-149).

Therefore, the time of perceived collapse would depend on the details of the environment.

A theoretical analysis of this problem and estimates of the time of perceived collapse are given for a specific model in (a very long article) (accepted for publication in Physics Reports - ).

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