Abstract

In a previous analysis, it was argued that greater insight into the origin of inertia cannot be obtained solely on the basis of inertial mass; the participation of space-time must also be taken into account. Special and general relativity were used to show that the origin of inertia is the distortion of time in accelerating systems of reference. Herein, the behavior of light in accelerating coordinates is used to provide further evidence that time distortion is the source of inertia. We consider a sealed vessel that contains a photon gas and resides in a uniform acceleration field. It is shown that radiation pressure exerts a net force on the vessel whenever space-time structure gives rise to a relativistic Doppler-shift that is observable in the co-moving reference frame of the vessel. Then the force is expressed in terms of space-time distortion in the reference frame of an infinitesimal small vessel residing in a Newtonian acceleration field. Carrying this out leads to an expression in agreement with the previous analysis, in which the force of inertia is derived on the basis of special and general relativity. The resulting expression implies that any entity possessing energy, regardless of embodiment, exhibits inertial properties; and more particularly, that the origin of inertia is the relativistic nature of time.