Quantum physics accounts for the collapse of the wave function (and thus for the emergence of “ordinary” reality) in terms of the act of perception/registration (a single reality emerges through the act of measurement), but it then explains (or, rather, describes) this measurement in terms of the ordinary reality that only emerges through it (the measuring machine is hit by electrons, etc.), and this obviously involves a vicious circle.
What this means is that the big problem is not how we can pass from the classic universe to the universe of quantum waves, but exactly the opposite one—why and how the quantum universe itself immanently requires the collapse of the wave function, its “de-coherence” into the classic universe, i.e., why and how the collapse is inherent to the quantum universe. Instead of just standing in awe before the wonder of the quantum universe, we should turn around our perspective and perceive as the true wonder the rise of our “ordinary” spatio-temporal reality. It is not only that there is no classic reality which is not sustained by blurred quantum fluctuations; one should add that there is no quantum universe which is not always-already hooked onto a piece of classic reality. The problem of the collapse of the wave function through the act of measurement is that it has to be formulated in classic, not quantum, terms—this is why “the collapse of the wave function occupies an anomalous position within quantum mechanics. It is required by the fact that observations occur, but it is not predicted by quantum theory. It is an additional postulate, which must be made in order that quantum mechanics be consistent.” One should note this precise formulation: a measurement formulated in terms of classic reality is necessary for quantum mechanics itself to be consistent, it is an addition of the classic reality which “sutures” the quantum field. What, then, is the status of “quantum reality,” i.e., of the so-called wave function Fi which renders the panoply of superimposed states?
>Are we to regard Fi as actually representing physical reality? Or is it to be viewed as being merely a calculational tool for working out probabilities of the results of experiments that might be performed, the results of these being “real,” but not the wave function itself? … It was part of the Copenhagen interpretation of quantum mechanics to take this latter viewpoint, and, according to various other schools of thought alsPost too long. Click here to view the full text.