The antipodal identification as a new boundary condition on the horizon, and how it comes about

          @misc{ scivideos_PIRSA:19090008,
            doi = {10.48660/19090008},
            url = {https://pirsa.org/19090008},
            author = {{\textquoteright}t Hooft, Gerard},
            keywords = {Cosmology, Particle Physics, Strong Gravity},
            language = {en},
            title = {The antipodal identification as a new boundary condition on the horizon, and how it comes about},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2019},
            month = {sep},
            note = {PIRSA:19090008 see, \url{https://scivideos.org/pirsa/19090008}}
          }
          

Abstract

Quantizing the black hole can be done without String Theory, fuzz balls, AdS/CFT and such. We just assume matter to keep the form of point particles until they come close to the horizon. The gravitational back reaction of these particles generates a novel relation between particles going in and particles going out, enabling us to transform in-going particles into out-going ones. This transformation removes "firewalls" along the future and past horizons, but it strongly affects space-time inside a black hole. It subsequently allows us, and indeed forces us, to identify antipodal points on the horizon. We argue that this is the only way to restore unitarity for the quantum evolution operator, and to identify the black hole microstates. Some mysteries, however, remain unresolved.