Topics in asymptotically flat gravity in 3 and 4 dimensions
Abstract:
In 3 dimensions, it is shown that asymptotically flat spacetimes and their symmetries can be understood as a modified Penrose limit of their anti-de Sitter counterparts.
In analogy with the higher spin extension of 3d anti-de Sitter gravity, an infinite dimensional extension of 3d flat gravity involving the Virasoro algebra is presented in the Chern-Simons formulation.
In 4 dimensions, we briefly review in what sense asymptotically flat gravity is describedby an extended conformal field theory.