Conceptual Difficulties of Standard Quantum Mechanics and the Role of Noise in Overcoming Them

Abstract

We briefly review the difficulties of the standard version of quantum mechanics in accounting for all kinds of physical processes (in particular both the micro and the macroscopic ones) and we argue that to overcome such difficulties one has to give up the superposition principle, i.e., to break the linear nature of the theory. We then show that the simple introduction of terms violating the linearity of the deterministic evolution of the standard theory has physically unacceptable consequences. Taking this into account we are led to modify the quantum dynamics by adding to Schrödinger’s equation, besides nonlinear terms, a coupling with an appropriate noise. We show that, with such a move, one can work out a theory which is internally consistent and it allows to account, in a quite simple and physically appealing way, for natural processes including the measurements and the classical behavior of macroscopic bodies. On the basis of our analysis, we are led to conclude that the consideration of the noise represents a crucial element for understanding the laws of nature.