Null Surface Thermodynamics

Abstract: In this talk, I'm going to formulate the D-dimensional Einstein gravity in presence of a codimension one null boundary. As we will see in addition to the bulk degrees of freedom that propagate into the bulk we also have to account for the boundary degrees of freedom that reside at the boundary. A suitable way to label these boundary degrees of freedom is using the surface charges associated with large diffeomorphisms. Surprisingly, we will also observe these boundary degrees of freedom describe a thermodynamic system with local laws of thermodynamics. This thermodynamical system is generally an open system and can be closed only when there is no flux of gravitons through the null surface. Local laws of thermodynamics are a manifestation of diffeomorphism invariance of the theory at the boundary and account for the dynamics of the part of spacetime behind the boundary. Our analysis extends the usual black hole thermodynamics to a universal feature of any area element on a generic null surface in a generic diffeomorphism invariant theory of gravity.

HEP - theorymathematical physics

Audience: researchers in the topic

Physics @ Boundaries Workshop