To the rescue of Copenhagen interpretation

TL;DR

This paper critically examines recent claims challenging the Copenhagen interpretation of quantum mechanics, proposing novel perspectives that preserve its validity and clarifying misconceptions about Wigner's friend thought experiment.

Contribution

It introduces a new interpretation where Wigner's friend perceives no outcomes, addressing the controversy and defending the Copenhagen interpretation against recent critiques.

Findings

The Copenhagen interpretation remains consistent when considering subjective perceptions.

Wigner's friend might perceive no outcomes in the thought experiment.

Real experiments on Wigner's friend would not yield new insights into quantum mechanics.

Abstract

A recent paper "Single-world interpretations of quantum theory cannot be self-consistent" [arXiv:1604.07422] by D. Frauchiger and R. Renner has attracted a considerable interest of a broader physics audience and shortly elicited a number of replies. In spite of the objections that ensued, we find that significant part of the controversial initial claim has not been refuted - on the contrary, arguments presented both in the initial paper and in the replies seem to leave no longer room for the basic Copenhagen interpretation of quantum mechanics. We revisit the controversy trying to pinpoint the exact phenomenon that lies in its core, pointing out to some aspects of the problem that seem to have been mostly overlooked. Taking all conclusions into account, we here propose novel ways to approach the ostensible paradox, in which the Copenhagen interpretation is naturally preserved. Whereas arguments presented in Frauchiger and Renner paper and the replies that followed revolve over whether Wigner's friend would perceive only one or both of the possible outcomes, we offer the third, pretty obvious solution - namely, that Wigner's friend, in the well known setup, would subjectively perceive {\it none} of the potentially conflicting outcomes. As a side note, we also argue that, contrary to the often stated beliefs, hypothetical real experimental realization of Wigner's friend thought experiment actually would not provide us with any new insight into the quantum mechanics.