On the consistency of relative facts

Eric G Cavalcanti; Andrea Di Biagio; Carlo Rovelli

doi:10.1007/s13194-023-00551-8

On the consistency of relative facts

Eur J Philos Sci. 2023;13(4):55. doi: 10.1007/s13194-023-00551-8. Epub 2023 Nov 22.

Authors

Eric G Cavalcanti¹, Andrea Di Biagio^{2

3}, Carlo Rovelli^{4

5

6}

Affiliations

¹ Centre for Quantum Dynamics, Griffith University, Gold Coast, QLD 4222 Yugambeh Country Australia.
² Institute for Quantum Optics and Quantum Information (IQOQI) Vienna, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria.
³ Basic Research Community for Physics e.V., Mariannenstraße 89, Leipzig, Germany.
⁴ CPT, Aix-Marseille University,Université de Toulon and CNRS, Luminy, Marseille, France.
⁵ Department of Philosophy and Rotman Institute of Philosophy, Western University, London ON, Canada.
⁶ Perimeter Institute, 31 Caroline Street N, Waterloo ON, Canada.

Abstract

Lawrence et al. have presented an argument purporting to show that "relative facts do not exist" and, consequently, "Relational Quantum Mechanics is incompatible with quantum mechanics". The argument is based on a GHZ-like contradiction between constraints satisfied by measurement outcomes in an extended Wigner's friend scenario. Here we present a strengthened version of the argument, and show why, contrary to the claim by Lawrence et al., these arguments do not contradict the consistency of a theory of relative facts. Rather, considering this argument helps clarify how one should not think about a theory of relative facts, like RQM.

Keywords: Quantum foundations; Relational quantum mechanics; Relative events; Wigner’s friend paradox.