 His research interests were centered on supersymmetry and supergravity, from phenomenology (namely how to find evidence for supersymmetry at current and planned particle accelerators or in the guise of dark matter) to more theoretical questions of string and M theory.In the context of general relativity, he was best known for his development (with Stanley Deser and Charles Misner) of the ADM formalism, roughly speaking a way of describing spacetime as space evolving in time, which allows a recasting of Einstein's theory in terms of a more general formalism used in physics to describe dynamical systems, namely the Hamiltonian formalism.In the framework of that formalism, there is also a straightforward way to globally define quantities like energy or, equivalently, mass (so-called ADM mass/energy) which, in general relativity, is not trivial at all.