Time Symmetric Quantum Theory Without Retrocausality

TL;DR

The paper critiques a recent argument claiming time-symmetric quantum theories cannot avoid retrocausality, highlighting a critical flaw and suggesting alternative interpretations are possible without retrocausality.

Contribution

It analyzes and refutes a recent proof against retrocausal interpretations, proposing that time symmetry in quantum theory can exist without retrocausality.

Findings

The central proof in the criticized paper contains a fatal error.

Interpretations without retrocausality can still be time symmetric.

No current prospects for a theorem disproving retrocausal interpretations.

Abstract

In their recent paper "Is a Time Symmetric Interpretation of Quantum Theory Possible Without Retrocausality?", Matthew Leifer and Matthew Pusey argue that the answer to their title question is "no". Unfortunately, the central proof offered in the paper contains a fatal error, and the conclusion cannot be established. Interpretations of quantum theory without retrocausalty can be time symmetric not only in the traditional sense but also in Leifer and Pusey's supposedly stricter sense. There appear to be no prospects for proving any analogous theorem.