# Bondi-Sachs energy The Bondi-Sachs energy is a definition of [[0592 Gravitational energy|gravitational energy]] in General Relativity. It is defined on the null infinity and can change along the null direction of null infinity. Contrast this with the [[0487 ADM mass|ADM energy]], which is defined at spatial infinity. ## Refs - original - [[1962#Bondi, van der Burg, Metzner]] - [[1962#Sachs]]