Yannick Herfray - Cartan geometry of null infinity
A feature of General Relativity is the interplay between physics and geometry. An beautiful instance of this fact is realised at null infinity where asymptotic gravitational data are realised geometrically as a boundary « conformal Carrollian geometry », with the BMS group acting as a group of symmetry. The invariant meaning (and geometrical elegance) lying behind these however only fully appear in the language of Cartan geometry. I will explain this as well as relationship to other related constructions such as local twistors and Ashtekar’s radiative structure.
A feature of General Relativity is the interplay between physics and geometry. An beautiful instance of this fact is realised at null infinity where asymptotic gravitational data are realised geometrically as a boundary « conformal Carrollian geometry », with the BMS group acting as a group of symmetry. The invariant meaning (and geometrical elegance) lying behind these however only fully appear in the language of Cartan geometry. I will explain this as well as relationship to other related constructions such as local twistors and Ashtekar’s radiative structure.