Limitations of Gravitational Physics in the Early Universe

Abstract

Evidence from recent astrophysical experiments - including the James Webb Telescope (JWST) and Pulsar Timing Arrays (PTA) - reveals potential inconsistencies with standard Big-Bang cosmology [1-4]. Several competing explanations of these (and similar) anomalies have been suggested, but a conclusive resolution is yet to be seen. The object of this brief note is to bring up a key challenge faced by classical gravity in far-from-equilibrium conditions. These conditions exist in the very early stages of cosmological evolution and point to a paradigm shift in our understanding of foundational physics.