Unified dynamics for microscopic and macroscopic systems
Abstract
An explicit model allowing a unified description of microscopic and macroscopic systems is exhibited. First, a modified quantum dynamics for the description of macroscopic objects is constructed and it is shown that it forbids the occurrence of linear superpositions of states localized in faraway spatial regions and induces an evolution agreeing with classical mechanics. This dynamics also allows a description of the evolution in terms of trajectories. To set up a unified description of all physical phenomena, a modification of the dynamics, with respect to the standard Hamiltonian one, is then postulated also for microscopic systems. It is shown that one can consistently deduce from it the previously considered dynamics for the center of mass of macroscopic systems. Choosing in an appropriate way the parameters of the soobtained model one can show that both the standard quantum theory for microscopic objects and the classical behavior for macroscopic objects can all be derived in a consistent way. In the case of a macroscopic system one can obtain, by means of appropriate approximations, a description of the evolution in terms of a phasespace density distribution obeying a FokkerPlanck diffusion equation. The model also provides the basis for a conceptually appealing description of quantum measurement.
 Publication:

Physical Review D
 Pub Date:
 July 1986
 DOI:
 10.1103/PhysRevD.34.470
 Bibcode:
 1986PhRvD..34..470G
 Keywords:

 03.65.Bz