2021/03/31 by Geoffrey Compère, Compère, Geoffrey, David A. Nichols +1 · 2 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th) #Pulsars and Gravitational Waves Research #gr-qc #hep-th
paper · pdf · doi:10.48550/arxiv.2103.17103
Essay written for the Gravity Research Foundation 2021 Awards for Essays on Gravitation
arxiv created 2021/03/31 · openalex publication_date 2021/03/31 · arxiv updated 2021/04/01 · openalex created_date 2021/04/13 · openalex updated_date 2026/07/28
Angular momentum at null infinity has a supertranslation ambiguity from the lack of a preferred Poincaré group and a similar ambiguity when the center-of-mass position changes as linear momentum is radiated. Recently, we noted there is an additional one-parameter ambiguity in the possible definitions of angular momentum and center-of-mass charge. We argue that this one-parameter ambiguity can be resolved by considering the generalized BMS charges that are constructed from local 2-sphere-covariant tensors near null infinity; these supertranslation-covariant charges differ from several expressions currently used. Quantizing angular momentum requires a supertranslation-invariant angular momentum in the center-of-mass frame. We propose one such definition of angular momentum involving nonlocal quantities on the 2-sphere, which could be used to define a quantum notion of general-relativistic angular momentum.