An objective background for quantum theory relying on thermodynamic concepts

We come back to the rooting of quantum theory in an objectively given phenomenological context, as it was first sustained by Bohr and later taken by Ludwig as basic motivation of his axiomatic approach. It is shown that the question of compatibility of an objective phenomenological context with present day quantum theory can be answered in a positive way if also thermodynamic concepts are taken into account for a quantum description of macroscopic systems. A formalism is recalled accounting for non equilibrium thermodynamics, by introducing classical fields describing local equilibrium in the quantum field context. Also a non deterministic dynamical evolution of these classical fields appears as an important possibility, linked to the breakdown of the method appropriate for the deterministic case. In this connection a refinement of this method is indicated, which with some additional condition leads to the concept of microsystem and to quantum theory for particles interacting with a macrosystem.