Centre de Physique Théorique


Vendredi 28 mai 2021

14h00 – 15h00,

New symmetries of General Relativity

Simone Speziale

Noether’s theorem has a subtle but beautiful application to theories
with local gauge symmetries : if boundaries are present, gauge acquires
a precise physical sense, and it is possible to study conservation
laws and flux-balance laws associated with 2d surface charges. In the
case of general relativity, these charges are associated with the BMS
group, and play a fundamental role in the physical interpretation of
gravitational wave signals at LIGO/Virgo. Developments of the last few
years, spurred by Strominger’s new analysis of Weinberg’s soft
theorem, suggest that the BMS group is too small to capture all the
relevant physics, and that the true asymptotic symmetry of general
relativity is larger. In this talk I will give an introduction to
these topics, and present a candidate extension called the Weyl BMS
group. I will motivate this extension on theoretical grounds, discuss
its geometric meaning, but also mention future work that can lead to
observational effects of the extension.