On the Nature of Inertia
Charles T. Ridgely
We show that special and general relativity provide a clear statement regarding the origin of inertia. We begin by pointing out that according to general relativity, inertial and gravitational forces arise directly out of the structure of space-time. This implies that an adequate description of inertia cannot be obtained solely on the basis of inertial mass; the role played by space-time must also be considered. General relativity is then used to derive the proper force experienced by a uniformly accelerating observer. Next, we use special relativity to derive the inertial resistance of an observer accelerating under the influence of a constant external force in flat, Minkowski space-time. Both analyses imply that the origin of inertia resides in a relationship between the energy content of matter and the local structure of time. We ultimately conclude that the origin of inertia is the relativistic nature of time.
