On the Status of the Geodesic Principle in Newtonian and Relativistic Physics

Understand

A theorem due to Bob Geroch and Pong Soo Jang ["Motion of a Body in General Relativity." Journal of Mathematical Physics 16(1), (1975)] provides a sense in which the geodesic principle has the status of a theorem in General Relativity (GR).

• I have recently shown that a similar theorem holds in the context of geometrized Newtonian gravitation (Newton-Cartan theory) [Weatherall, J.
• O.
• "The Motion of a Body in Newtonian Theories." Journal of Mathematical Physics 52(3), (2011)].