Beijing Institute of Mathematical Sciences and Applications

Hamed Adami , Chi Ming Chang , Mohammad Yavartanoo

Kostas Skenderis

Thursday, June 9, 2022 4:30 PM - 5:30 PM

1129B

Zoom 361 038 6975 (BIMSA)

The proper definition of conserved charges in gravitational theories is a notoriously difficult problem. Diffeomorphism invariance implies that non-trivial charges may only be defined as surface integrals at infinity but due to the infinite volume of spacetime any such definition requires a subtraction, potentially making the charges ambiguous. In this talk I will discuss the definition of conserved charges in asymptotically locally de Sitter spacetimes. De Sitter spacetimes have additional subtleties: there are no global timelike Killing vectors even for exact de Sitter and there is also no spacelike infinity; rather the asymptotic regions are in the time direction. We use methodology inspire from holography and the formalism of covariant phase space to discuss the construction of charges, discuss quantities which are conserved under time evolution in the absence of gravitational flux but otherwise change according to the amount of the net gravitational flux entering or leaving a spacetime region. The discussion will be illustrated with examples.