Würzburg Seminar on Quantum Field Theory and Gravity

Black holes are known to behave as thermodynamic systems, with a temperature and an entropy. In string theory, the origin of the black-hole entropy is explained from the multitude of ways the non-perturbative degrees of freedom (the D-branes) can interact when gravity is turned off. But what happens when gravity is turned back on? In this talk, I will review the hypothesis that individual black-hole microstates may not have a horizon and differ from the classical black-hole solution at the horizon scale. I will explain the in and outs of this paradigm, including its relation with respect to the black-hole information paradox. I will also explain the physics played by D-brane interactions in the internal dimensions. Finally, if time permits, I will explain how one could perhaps test the validity of this horizonless property of individual microstates through their collective behaviours, in particular quantum chaos.