# Comment to 'On the reality of the quantum state'

## TL;DR

This paper critiques Pusey, Barrett, and Rudolph's claim that { extbackslash}psi-epistemic quantum mechanics is incompatible with standard quantum mechanics, identifying a key assumption error related to the Projection Postulate.

## Contribution

It demonstrates that the original argument against { extbackslash}psi-epistemic models contains a flaw due to an incorrect assumption about the Projection Postulate.

## Key findings

- Identifies an error in the original proof by Pusey et al.
- Shows that the inconsistency claim is not conclusively established.
- Highlights the importance of the Projection Postulate in such arguments.

## Abstract

In Nature Phys. 8:475-478 (2012), Pusey, Barrett, and Rudolph have claimed that {\psi}-epistemic quantum mechanics (QM) is inconsistent with predictions of standard QM. Here we show that Pusey et al. err in the beginning of their argument by making an assumption that violates the Projection Postulate.

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Source: https://tomesphere.com/paper/1812.03035