Is Psi real?

Sabine Hossenfelder has a very interesting Youtube video (see this) telling about the article “Experimental demonstration of the PBR test on a superconducting processor” (see this). The experiments are argued to support the view that wavefunctions really exist and therefore the ontic view of quantum theory.

To my first understanding, the argument goes very roughly as follows.

1. By reading the original article one learns that there are 3 options: a) epistemic option (EO), b) hidden variable option, and c) ontic option. For a) given values of hidden variables can correspond to several quantum states and for b) only to a single one: in this case one can say that quantum state describes reality rather than our incomplete knowledge of it. For option c) hidden variables could mean finite measurement resolution so that the state in a given resolution can correspond to several states in an improved resolution.

In EO there are hidden variables and Ψ gives a kind of average description. In state function reduction it is updated. Sabine however notes that Bohr proposed epistemic interpretation but did not accept hidden variables!

Measurement errors are however present and the deviation from IP prediction allowed by the epistemic option could be interpreted as measurement error if one is not careful. One must construct a model for measurement errors and show that the measurement errors are below the bounds predicted by the EO.

This is done and the conclusion is that the findings exclude the epistemic option. How does this relate to TGD? Already in the relativistic wave mechanics Ψ is replaced with a spinor field and quantum states are constructed using fermionic oscillator operators so that the question is of whether the quantum states are real or only epistemic.

1. In the TGD framework, Ψ is replaced at the fundamental level by what I call spinor field in an infinite-D “world of classical worlds” (WCW). Its spinor structure can be seen as a “square root” of the metric structure and the Fock state basis provides a representation of Boolean algebra. Geometry and logic would be closely related.

WCW spinor modes are Fock states for the second quantized spinor fields in H=M⁴×CP₂. If WCW metric is real then also the fermion fields are. Same applies to space-time surfaces X⁴ as 4-D Bohr orbits or particle-like 3-surfaces and H.

For the lists of articles (most of them published in journals founded by Huping Hu) and books about TGD see this.