Light-cone reference for total gravitational energy - art. no. 104034

We give an explicit expression for gravitational energy, written solely in terms of physical spacetime geometry, which (in suitable limits) agrees wit h the total Arnowitt-Deser-Misner and Trautman-Bondi-Sachs energies for asy mptotically flat spacetimes and with the Abbott-Deser energy for asymptotic ally anti-de Sitter spacetimes. Our expression is a boundary value of the s tandard gravitational Hamiltonian. Moreover, although it stands alone as su ch, we derive the expression by picking the zero-point of energy via a "lig ht-cone reference.'' [S0556-2821(99)07420-2].