Lecture notes prepared for the 2021 SAGEX PhD School in Amplitudes hosted by the
University of Copenhagen August 10th through 13th. Topics covered include: the …

We review the role that infinite-dimensional symmetries arising at the boundary of
asymptotically flat spacetimes play in the context of the celestial holography program. Once …

We show that a 3D sourced conformal Carrollian field theory has the right kinematic
properties to holographically describe gravity in 4D asymptotically flat spacetime. The …

These notes consist of 3 lectures on celestial holography given at the Pre-Strings school
2021. We start by reviewing how semiclassically, the subleading soft graviton theorem …

A bstract All 4D gauge and gravitational theories in asymptotically flat spacetimes contain an
infinite number of non-trivial symmetries. They can be succinctly characterized by …

Recent attempts at the construction of holography for asymptotically flat spacetime have
taken two different routes. Celestial holography, involving a two dimensional (2D) conformal …

A short, graduate-level synthesis of recent developments in theoretical physics, from a
pioneer in the field Lectures on the Infrared Structure of Gravity and Gauge Theory presents …

Gravity in 4 d asymptotically flat spacetime constitutes the archetypal example of a
gravitational system with leaky boundary conditions. Pursuing our previous analysis of …

A bstract We propose an extension of the BMS group, which we refer to as Weyl BMS or
BMSW for short, that includes super-translations, local Weyl rescalings and arbitrary …

In this paper we extract from a large-r expansion of the vacuum Einstein's equations a
dynamical system governing the time evolution of an infinity of higher-spin charges. Upon …