A contextually objective approach to the extended Wigner's friend thought experiment

TL;DR

This paper proposes a contextually objective interpretation of quantum mechanics to resolve the extended Wigner's friend thought experiment, emphasizing the importance of agents' mutual agreement on systems to avoid contradictions.

Contribution

It introduces a novel, contextually objective approach using the CSM framework to eliminate apparent contradictions in the extended Wigner's friend scenario.

Findings

No contradiction arises when agents agree on what constitutes a system.

Mutual agreement is implicit in standard quantum mechanics formulations.

Removing the agreement leads to inconsistencies.

Abstract

We present a discussion of the extended Wigner's friend thought experiment proposed by Frauchiger and Renner in [1]. We show by using various arguments, including textbook quantum mechanics and the ontological approach of Contexts, Systems, Modalities (CSM), that no contradiction arises if one admits that agents must agree on what is considered as a system and what is not. In such a contextually objective approach of quantum mechanics, the apparent contradiction is automatically removed. We also discuss why this mutual agreement between agents is already implicit in the standard formulations of quantum mechanics, and why removing it leads to inconsistencies.