Asymptotic limit of null hypersurfaces

Abstract We study null hypersurfaces approaching null infinity in asymptotically flat spacetimes within the Bondi–Sachs gauge. The null Raychaudhuri constraint is shown to asymptote to the Bondi mass-loss formula, interpreted as a stress tensor conservation law. This stress tensor, the null Brown–York tensor, yields a Carrollian stress tensor at null infinity from the bulk. Furthermore, we establish that the canonical phase space on finite-distance null hypersurfaces asymptotes to the Ashtekar–Streubel phase space. This connection between finite-distance null physics and null infinity unveils promising insights.