Richard Lewis Arnowitt (May 3, 1928 – June 12, 2014) was an American physicist known for his contributions to theoretical particle physics and to general relativity.

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.

Arnowitt was also known for his work (with Ali Chamseddine and Pran Nath) which developed the theory of supergravity grand unification (with gravity mediated breaking).

This work allowed for the unification of the three forces of microscopic physics at a very high mass scale (a result subsequently indirectly verified at the CERN LEP accelerator).

In addition, Arnowitt's work (with Marvin Girardeau) on many body theory of liquid Helium has stimulated many applications in that field.