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Following the recent work of Henneaux and Troessaert, which revisits the problem of spacetime symmetries at spatial infinity, we analyze this problem using the Bondi metric without determinant condition as our starting point. It turns out that in this case the symmetries at spatial infinity form the BMS symmetry appended with an additional infinite set of abelian symmetries. We furthermore find that imposing the determinant condition to the Bondi metric would result in a drastic reduction of symmetries, with no spatial (super) translations present.
We study the covariant phase space of vacuum general relativity at the null boundary of causal diamonds. The past and future components of such a null boundary each have an infinite-dimensional symmetry algebra consisting of diffeomorphisms of the $2
It is shown that Ashtekar and Hansenss Universal Structure at Spatial Infinity (SPI), which has recently be used to establish the conservation of supercharges from past null infity to future null infinity, is an example of a (pseudo-) Carollian struc
Keplers rescaling becomes, when Eisenhart-Duval lifted to $5$-dimensional Bargmann gravitational wave spacetime, an ordinary spacetime symmetry for motion along null geodesics, which are the lifts of Keplerian trajectories. The lifted rescaling gener
After a brief review of topological gravity, we present a superspace approach to this theory. This formulation allows us to recover in a natural manner various known results and to gain some insight into the precise relationship between different app
We discuss some new developments in three-dimensional gravity with torsion, based on Riemann-Cartan geometry. Using the canonical approach, we study the structure of asymptotic symmetry, clarify its fundamental role in defining the gravitational cons