The Total Mass of a Particle in General Relativity

Without specifying otherwise the stress-energy distribution inside of a material particle, the assumption is made that the scalar quantity $T$, known in electromagnetism as the "scalar of Laue," shall vanish, in harmony with the Maxwellian stress tensor, and confirmed also by other considerations. It is shown that under this condition a theoretical explanation can be given of the long established empirical fact that the mass of any particle is necessarily positive. All metrical contributions to the total mass come out as necessarily positive, second-order quantities, with the only exception of an eventual spin, which has a decreasing instead of increasing effect on the mass. The strict proportionality of gravitational and and inertial mass can still be established, at least for the spherically symmetric case. The factor of proportionality, however, is numerically different from the value ordinarily assumed.