How the Natural Interpretation of Quantum Mechanics Avoids the Recent No-go Theorem

TL;DR

This paper demonstrates that a recent no-go theorem against quantum theory's self-description fails when quantum mechanics is interpreted statistically via the ensemble interpretation, highlighting the core statistical nature of QM and critiquing collapse mechanisms.

Contribution

It shows how the extended Wigner's friend argument fails under the ensemble interpretation and clarifies the statistical nature of quantum mechanics.

Findings

The no-go theorem is incorrect within the ensemble interpretation.

A consistent statistical treatment of the wave function is natural and effective.

Collapse mechanisms introduce unnecessary complications in quantum theory.

Abstract

A recent no-go theorem gives an extension of the Wigner's friend argument that purports to prove that "Quantum theory cannot consistently describe the use of itself." The argument is complex and thought provoking, but fails in a straightforward way if one treats QM as a statistical theory in the most fundamental sense, i.e. if one applies the so-called ensemble interpretation. This explanation is given here at an undergraduate level, which can be edifying for experts and students alike. A recent paper has already shown that the no-go theorem is incorrect with regard to the de Broglie Bohm theory and misguided in some of its general claims. This paper's contribution is three fold. It shows how the extended Wigner's friend argument fails in the ensemble interpretation. It also makes more evident how natural a consistent statistical treatment of the wave function is. In this way, the refutation of the argument is useful for bringing out the core statistical nature of QM. It, in addition, manifests the unnecessary complications and problems introduced by the collapse mechanism that is part of the Copenhagen interpretation. The paper uses the straightforwardness of the ensemble interpretation to make the no-go argument and its refutation more accessible.