Relativity and the a-theory

Abstract

The special theory of relativity (STR) is widely supposed to be in tension with theories of time which gives a special significance to the present moment. This chapter considers A-theoretic responses which accept STR, so far as it goes, but take it to be incomplete with respect to tensed facts. STR is a theory of the geometrical structure of space and time together: Minkowski spacetime. The theory postulates an underlying manifold of spacetime points. A model of STR yields a tenseless mosaic or manifold of all that happens and the spatiotemporal relations between these happenings. The A-theoretic picture of a wave of simultaneous happenings that sweeps through time, grounding tense in the four-dimensional manifold, is not straightforwardly compatible with STR, a tension dramatized by attempts to locate or impose a relation of absolute simultaneity on Minkowski spacetime. Conciliatory approaches trace the problems for the A-theory to the fact that each point of spacetime is part of many moments of time