Holo Club: ‘Brick wall Normal Modes and Emerging Thermality’
Speaker: Suman Das (IFT)
Title: ‘Brick wall Normal Modes and Emerging Thermality’
Abstract:
The ’t Hooft brick wall model provides one of the earliest microscopic derivations of the black-hole area law within the probe approximation of quantum field theory in curved spacetime. In this talk, I will revisit the original construction and present a modern perspective based on the spectral properties of the probe fields. After briefly reviewing how the area-proportional entropy arises in ’t Hooft’s setup, I will show that its origin can be understood in terms of the structure of the normal-mode spectrum. In particular, a quasi-degenerate growth of states along a specific quantum-number direction leads directly to the area scaling of the entropy.This viewpoint not only clarifies the mechanism behind the entropy but also reveals a number of non-trivial features of the spectrum, including signatures commonly associated with quantum chaos. I will discuss these features. Finally, I will show that, when the brick wall is placed parametrically close to the horizon, the two-point function of the probe field becomes indistinguishable from a thermal correlator, providing a precise sense in which thermality emerges in this framework.