The Standard Theory of Past, Present, and Future

Abstract

It has already been stated that within STR there appear two forms of the time relation earlier defined on the set S, and consequently, there are also two forms of the relations later and simultaneously. The first form is relative—i.e., dependent on the inertial reference system—relation earlier. In other words, not every two events which bear the relation to each other in one reference system will also bear it in another system. The same is true of the relative relations later and simultaneously, defined by means of the relative relation earlier.