Exploring the holographic principle in asymptotically flat spacetimes via the BMS group
Giovanni Arcioni, Claudio Dappiaggi
TL;DR
This work probes holography in asymptotically flat spacetimes through the Bondi–Metzner–Sachs (BMS) group, contrasting it with AdS/CFT and using the covariant entropy bound to link bulk entropy to boundary symmetries. It develops covariant wave equations for BMS representations via a fiber-bundle framework, analyzes the rich boundary structure including infinite-dimensional supertranslations, and discusses how holographic data might reside on the cone-space Bramson construction. The authors draw connections to 't Hooft’s S-matrix program for black holes and explore a tentative bulk–boundary mapping, emphasizing nonlocality and the lack of a unique bulk reconstruction in flat space. The paper highlights fundamental differences from AdS holography, identifies boundary degrees of freedom, and outlines substantial challenges and directions for forming a concrete flat-space holographic dictionary.
Abstract
We explore the holographic principle in the context of asymptotically flat spacetimes. In analogy with the AdS/CFT scenario we analyse the asympotically symmetry group of this class of spacetimes, the so called Bondi-Metzner-Sachs (BMS) group. We apply the covariant entropy bound to relate bulk entropy to boundary symmetries and find a quite different picture with respect to the asymptotically AdS case. We then derive the covariant wave equations for fields carrying BMS representations to investigate the nature of the boundary degrees of freedom. We find some similarities with 't Hooft S-matrix proposal and suggest a possible mechanism to encode bulk data.