A global and non-entropic arrow of time: the double role of the energy-momentum tensor

MARIO CASTAGNINO; OLIMPIA LOMBARDI

Córcega

Simposio; Le Temps á la Lumiére de l'Espace; 2003

Instutute de Cargese

In this paper we adopt a generic, global and non-entropic approach to the problem of the arrow of time, according to which the arrow of time is a generic, intrinsic and geometrical property of space-time. We demonstrate that the arrow of time so defined is generic in the sense that any space-time with physically reasonable properties (e.g. time-orientability and global time) will be endowed with an arrow of time. The only exceptions are very special cases belonging to a subset of zero measure of the set of all possible space-times. We also show the double role played by the energy-momentum tensor in the context of our approach. On the one hand, the energy-momentum tensor is the intermediate step that permits to turn the geometrical time-asymmetry of the universe into a local arrow of time manifested as a time-asymmetric energy flow. On the other hand, the energy-momentum tensor supplies the basis for deducing the time-asymmetry of quantum field theory, posed as an axiom in this theory.