Relational analysis of the Frauchiger--Renner paradox and interaction-free detection of records from the past

Abstract

We present an analysis of the Frauchiger-Renner Gedankenexperiment from the point of view of the relational interpretation of quantum mechanics. Our analysis shows that the paradox obtained by Frauchiger and Renner disappears if one rejects promoting one agent's certainty to another agent's certainty when it cannot be validated by records from the past. A by-product of our analysis is an interaction-free detection scheme for the existence of such records.