It’s the busiest time of my life right now! So I shouldn’t be blogging, but I couldn’t resist this. Holger F. Hofmann, is a distinguished quantum physicists and I’ve long been interested in his works. However, he has recently published a response to the paper by Pusey, Rudoph, Barrett (arXiv:1111.3328), titled “The quantum state should be interpreted statistically”, which I believe it’s a result of lack of communication with people working on ontological models of quantum theory. Hofmann claims that the paper by Pusey et. al. is invalid, because they assumed that there must be hidden variables intrinsic in nature. Of course PRB are aware of the fact that they are addressing an issue in the ψ-epistemic type of *ontological models*, and they have mentioned it in their paper. Stricktly speaking they haven’t assumed hidden variables (if by hidden variables you mean some extra degrees of freedom, which is not included in the wavefunction. Of course hidden variable theories are types of ontological models, but they are not the only ones)! They’ve assumed a reality behind the quantum states. In fact as far as I’m aware of his works, one of the authors (Barrett) is personally against the full realism in quantum world, due to the complexity of such a reality.
So anyone who doesn’t subscribe to any of those ontological models shouldn’t be bothered, as the paper doesn’t address their favourite theory. Of course there are many motivations to consider ontological models. If you are one of the people who see those motivations, then you should think of not considering statistical interpretation in your choice of model of quantum theory.
