Problems in relativity theory

Abstract

The dissertation consists of the following three parts: Part I: Mass. Different definitions of mass are discussed. The gravitational mass is shown to be proportional to the inertial mass not only in Newtonian theory but also in relativity theory, when a weak static field is considered. An expression for the mass density of a body in terms of the energy tensor is obtained in the latter case. It is further suggested that the stress components contribute to the mass of the body. Part II: Interpretation of the constants occurring in the solution for a charged particle in general relativity. The constants ([mu] and e), occurring in the solution for a charged particle are usually identified with the mass and the charge of the particle. According to the new interpretation [mu] is found to be the sum of the mass of the central particle and the mass equivalent to the electromagnetic energy of the field. The expression for the density of electromagnetic energy in the relativistic case is twice the corresponding expression in the classical theory. The difference is shown to be a consequence of the fact that the trace of the electromagnetic tensor vanishes. Part III: Negative Mass. Hypothetical netural atoms of negative mass consist of nucleus, with negative mass and positive charge, and electrons, with positive mass and negative charge. On account of the mutual gravitational repulsion, neutral particles of negative mass have a tendency to fly apart. If it is assumed that a body of negative mass emits radiation, it is found that Planck's constant must be negative.