The quantum could be real

As mentioned below, a recent paper on quantum mechanics got a lot of attention for supposedly proving something about the reality of wave functions. Holger F. Hofmann (German name, Japanese address) explains precisely what is wrong with it, consistent with what I said here:

In a recent paper (arXiv:1111.3328), Pusey, Barrett and Rudolph claim to proof that statistical interpretations of quantum mechanics do not work. In fact, their proof assumes that all statistical interpretations must be based on hidden variable realism. Effectively, the authors demand from the start that reality must be decided by mathematics, and not by measurements. If this unjustified assumption is dropped, the quantum formalism has a natural statistical interpretation that fully explains the paradox presented by the authors. It is therefore possible to conclude that the paradox actually supports the statistical interpretation, demonstrating once more that quantum mechanics should not be explained by measurement independent realities that are never observed and therefore lie beyond the reach of empirical tests. ...

Although the paper also presents a nice little toy model that certainly has merit as a useful addition to the cabinet of quantum paradoxes, the analysis of the model does not really support the sweeping conclusions drawn fromit. Specifically, the authors merely analyze a hidden variable model, implicitly assuming that any statistical theory of quantum mechanics must also assume a measurement independent reality. ...

The explanations given by Bohr, Heisenberg, von Neumann and many others all assume that (a) quantum mechanics should be interpreted statistically, and (b) hidden variables do not work. ...

I would like to point out that the conclusions presented by the authors actually support the statistical interpretation of the quantum state, once the empirically unjustified assumption of dogmatic realism is dropped. In fact, the authors provide several arguments in favor of the statistical interpretation - mainly, that the collapse of the wavefunction is fully explained and loses its mystery. Likewise, entanglement loses much of its mystery.

That's right. It seems as if there is always some physicist arguing that some particular hidden variable theory does not work, and claiming that he has discovered something profound about quantum mechanics being contrary to reality. No, saying that hidden variable theory does not work has been conventional wisdom since 1932. That is what Einstein was complaining about in the 1930s, as well as Bohm and Bell later.

The faulty assumption is indeed that "reality must be decided by mathematics, and not by measurements." From that assumption, they claim to prove that there is no reality. But another possibility is that there is an objective physical reality, but we don't have a good mathematical representation of it. Quantum mechanics gives us a good mathematical theory of measurement, but there is no proof that all physical entities are amenable to our mathematical models.

Different philosophies of reality are possible, as there are different interpretations of quantum mechanics. But it is inexcusable to promote some particular view as being correct, because some hidden variable theory is wrong, without even mentioning the orthodox view that was proposed in 1925 and accepted in 1932. That 1932 view is still tenable today.