The Four–Dimensional Spacetime

Abstract

Physics theories are made by building mathematical models that correspond to physical systems. General Relativity, the physical theory of Gravitation, models spacetime in a geometrical way: as a four–dimensional manifold. The concept of manifold is just a generalization to the multidimensional case of the usual concept of a two–dimensional surface. This will allow us to apply the well known tools of di.erential geometry, the branch of mathematics which describes surfaces, to the study of spacetime geometry.