Conventional Quantum Theory Does Not Support A Coherent Relational Account

TL;DR

This paper argues that conventional quantum theory cannot support a coherent relational interpretation due to measurement paradoxes and inconsistencies among observers, challenging recent defenses of relational quantum mechanics.

Contribution

It demonstrates that the attempt to defend relational quantum mechanics from measurement inconsistencies is unsuccessful, highlighting fundamental issues in the theory's coherence.

Findings

Inconsistencies among observers can be revealed in quantum measurement scenarios.

Recent defenses of relational quantum mechanics do not resolve these measurement paradoxes.

The paper discusses broader implications for the viability of quantum theory formulations.

Abstract

Quantum theory in its conventional formulation is notoriously subject to various measurement-related paradoxes, as exemplified by the "Schrodinger's Cat" and "Wigner's Friend" thought experiments. It has been shown, for example by Frauchiger and Renner, that nested measurements such as those occurring in the Wigner's Friend experiment can lead to inconsistencies concerning the putative outcomes of measurements. Such inconsistencies are commonly presumed to remain private and incommensurable, but this is not the case. A counterexample, in which the inconsistencies can be revealed among the observers, is reviewed. The implications for a recent attempt to shield Relational Quantum Mechanics from such inconsistencies are considered, and it is concluded that the attempt is not successful. Further implications for the state of the debate concerning the viability of quantum theory in its various formulations are discussed.