Relational Perspectives in Quantum Gravity: The Role of Quantum.... - Anne-Catherine de la Hamette скачать в хорошем качестве

Relational Perspectives in Quantum Gravity: The Role of Quantum.... - Anne-Catherine de la Hamette

Workshop on Quantum Aspects of Black Holes and Spacetime Topic: Relational Perspectives in Quantum Gravity: The Role of Quantum Reference Frames Speaker: Anne-Catherine de la Hamette  Affiliation: ETH Zürich Date: December 4, 2025 Wolfensohn Hall The framework of quantum reference frames (QRFs) lies at the crossroads of quantum information, gauge theory, quantum field theory, and quantum gravity, and has seen rapid progress in recent years. After introducing the perspective-neutral formulation, I will present two applications demonstrating how QRFs illuminate quantum aspects of spacetime. First, I will show how QRF methods yield concrete predictions for quantum effects in superposed spacetimes—reproducing perturbative results where applicable while extending naturally to non-perturbative regimes where no fixed background exists. Second, I will discuss recent advances showing how modeling observers as quantum systems leads to crossed product algebras and type reduction, transforming Type III algebras (which lack a well-defined trace) into Type II structures with finite entropies. This regularization reveals that different observers may measure different gravitational entropies, suggesting some entanglement entropies are fundamentally observer-dependent. I will conclude by outlining several open questions about the role of observers in quantum gravity, including whether certain divergences and paradoxes might reflect the limits of frame-independent descriptions rather than fundamental inconsistencies.