Orateur
Description
I will present a common description of null infinity and physical
horizons, highlighting the geometric properties they share, and the
origin of the radically different physics they describe. The common
description offers new perspectives on the different symmetry groups
considered at finite distance. I will then show how ambiguities in the
construction of charges from Noether's theorem are removed using a
prescription due to Wald and Zoupas, for both null infinity and the
finite distance case, and how the results match with the method by
Ashtekar and Streubel. I will then show how the method of Barnich and
Brandt can be also brought in agreement, in particular how the
covariance requirement removes any field-dependent 2-cocycle in the
realization of the symmetry algebra. Finally, I will summarize the
status of the Wald-Zoupas prescription for different enlargements of
the BMS symmetry currently under study.
