Roberto Emparan (University of Barcelona), Observing Quantum Gravity in Extremely Cold Horizons

Tuesday 7 Apr 2026, 11:15 → 12:30 Europe/Stockholm

Albano 3: 6228 - Mega (22 seats) (Albano Building 3)

Abstract: Recent developments have revealed that black holes near extremality exhibit large quantum fluctuations in their geometry, marking a controllable breakdown of semiclassical quantum field theory in curved spacetime. In this talk, I will discuss how these fluctuations can be revealed through scattering waves off the black hole. In particular, we find that extremely cold black holes look larger when probed with scalar fields, but become transparent to low-frequency light or gravitational radiation. Although such signatures are extraordinarily hard to detect, they provide concrete signatures of quantum gravity at play in near-extremal regimes.