Collapse of the wave function: models, ontology, origin, and implications

In standard quantum mechanics, it is postulated that when the wave function of a quantum system is measured, it no longer follows the Schrödinger equation, but instantaneously and randomly collapses to one of the wave functions that correspond to definite measurement results.

However, why and how a definite measurement result appears is unknown.

A promising solution to this problem are collapse theories in which the collapse of the wave function is spontaneous and dynamical.

Chapters written by distinguished physicists and philosophers of physics discuss the origin and implications of wave-function collapse, the controversies around collapse models and their ontologies, and new arguments for the reality of wave function collapse.