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Limits of absoluteness of observed events in timelike scenarios: A no-go theorem

Sumit Mukherjee1,2,* and Jonte R. Hance3,4,†

  • *Contact author: mukherjeesumit93@gmail.com
  • †Contact author: jonte.hance@newcastle.ac.uk
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Phys. Rev. Research 8, 023066 – Published 22 April, 2026

DOI: https://doi.org/10.1103/1c6t-45g8

Abstract

Wigner's Friend-type paradoxes challenge the assumption that events are absolute—that when we measure a system, we obtain a single result, which is not relative to anything or anyone else. These paradoxes highlight the tension between quantum theory and our intuitions about reality being observer independent. Building on a recent result that developed these paradoxes into a no-go theorem, namely, the Local Friendliness theorem, we introduce the Causal Time-Symmetric Friendliness Paradox, a time-ordered analog of it. In this framework, we replace the usual locality assumption with Axiological Time Symmetry and show that, when combined with the assumptions of Absoluteness of Observed Events (AOE), No Retrocausality, and Screening via Pseudo Events, we obtain a Causal Time-Symmetric Friendliness inequality. We then show that quantum mechanics violates this inequality and is therefore incompatible with at least one of these assumptions. To probe which assumption might be incompatible, we then examine whether AOE in its entirety is essential for this no-go result. We propose a weaker, operational form of AOE that still leads to inequalities that quantum mechanics violates. This result shows that even under relaxed assumptions, quantum theory resists reconciliation with classical notions of absolute events, reinforcing the foundational significance of Wigner's Friend-type paradoxes in timelike scenarios.

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Phys. Rev. Research 8, 023066– Published 22 April, 2026
  • Received 31 October 2025
  • Revised 5 February 2026
  • Accepted 30 March 2026
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