Fulling-Davies-Unruh effect in classical field theory.

Abstract

We analyze the field radiation due to a general source in the inertial and accelerated frames in classical massless scalar field theory in Minkowski spacetime. The classical particle numbers in these frames are defined and further justified in the context of quantum mechanics. The simple relation between the two expressions shows how some aspects of the Fulling-Davies-Unruh thermal bath are present in classical field theory. Finally we show how our results and an operator algebra can be used to obtain an operator expression for the Fulling-Davies-Unruh effect. We also comment on the expected analogue of our results for the Schwarzschild black hole.