BMS invariance and the membrane paradigm

TL;DR

This paper reveals that the infinite symmetries and conservation laws of the BMS group are equivalent to those of the membrane paradigm, linking asymptotic symmetries to black hole horizon physics and broadening their applicability.

Contribution

It demonstrates the equivalence between BMS symmetries and membrane paradigm symmetries, providing new insights into conservation laws and their physical interpretation.

Findings

BMS symmetries match membrane paradigm symmetries

Conservation laws extend to arbitrary null surface subregions

Clarifies the superrotation subgroup of BMS group

Abstract

The Bondi-van der Burg-Metzner-Sachs (BMS) group is the asymptotic symmetry group of asymptotically flat spacetime. It is infinite dimensional and entails an infinite number of conservation laws. According to the black hole membrane paradigm, null infinity (in asymptotically flat spacetime) and black hole event horizons behave like fluid membranes. The fluid dynamics of the membrane is governed by an infinite set of symmetries and conservation laws. Our main result is to point out that the infinite set of symmetries and conserved charges of the BMS group and the membrane paradigm are the same. This relationship has several consequences. First, it sheds light on the physical interpretation of BMS conservation laws. Second, it generalizes the BMS conservation laws to arbitrary subregions of arbitrary null surfaces. Third, it clarifies the identification of the superrotation subgroup of the BMS group. We briefly comment on the black hole information problem.