Time in quantum gravity.

          @misc{ pirsa_PIRSA:25060055,
            doi = {10.48660/25060055},
            url = {https://pirsa.org/25060055},
            author = {Freidel, Laurent},
            keywords = {},
            language = {en},
            title = {Time in quantum gravity.},
            publisher = {Perimeter Institute},
            year = {2025},
            month = {jun},
            note = {PIRSA:25060055 see, \url{https://pirsa.org}}
          }
          

Abstract

In this talk, I will investigate the possibility of time being a fundamental physical entity in quantum gravity. I will briefly review the different notions of time in classical and quantum mechanics and then focus on explaining the fundamental clash that exists between the notions of time in Quantum Field theory and general relativity. This clash, related to the so-called problem of time, is at the core of the fundamental difficulty of quantizing gravity. I will review how recent results in Quantum gravity allow a surprising resolution of this fundamental puzzle through the presence of a quantum anomaly, which promotes time to a fundamental quantum observable in quantum gravity.