Wigner's friend black hole adventure: an argument for complementarity?Confirmed

by Laurens Walleghem (University of York)

Thursday Feb 12, 2026, 11:00 AM → 12:30 PM America/Toronto

PI/3-301 - Alice Room (Perimeter Institute for Theoretical Physics)

At the heart of both Wigner's friend paradoxes and black hole puzzles lies the question of unitarity. In Wigner’s friend setups, sealed-lab measurements are modeled unitarily, probing the measurement problem. In black hole physics, the unitarity problem concerns information preservation in evaporation. In this talk, I discuss a refined version of the Frauchiger–Renner paradox and extend a recent analogy between Wigner's friend and black hole paradoxes exposed by Hausmann and Renner [arXiv:2504.03835v1], by constructing new paradoxes that merge black hole physics with nonlocal extensions of Wigner’s friend scenarios into a unified argument. I shortly discuss implications of these works, highlight some subtleties in black hole puzzles, and end with some speculations.