Radiative degrees of freedom of the gravitational field in exact general relativity

The radiative degrees of freedom of the gravitational field are isolated by analyzing the structure available at null infinity, 𝒥It is shown thay they are coded in certain equivalence classes D of connections; all information about gravitational radiation can be extracted from the curvature tensors of these connections directly on 𝒥 without any reference to the interior of space–time. The space of classical vacua—i. e. , of D with trivial curvature—is analyzed. It is shown that the quotient ST/T of the BMS supertranslation group by its translation subgroup acts simply and transitively on this space. The available structure is compared with that of gauge theories. Since the entire discussion can be carried out on𝒥 without any reference to the interior, it suggests a new approach to quantum gravity. This approach will be presented in detail in a subsequent paper.