Reviewed by Peter J. Lewis, Dartmouth College
Shan Gao (2017), The Meaning of the Wave Function: In Search of the Ontology of Quantum Mechanics. Cambridge: Cambridge University Press.
Shan Gao has written an exemplary book on the nature of the wave function—its theoretical role, the ontology it represents, and how understanding this ontology can contribute to solving the measurement problem. These themes are connected by a single line of argument that runs through the book from beginning to end. The argument is presented clearly and concisely, and the relevant philosophical and physical background is explained with admirable clarity and precision, without either excessive verbiage or unnecessary technicality. Gao’s proposed solutions to the foundational problems of quantum mechanics are clear, novel, and well-motivated.
In the course of his argument, Gao offers three distinct contributions to understanding the foundations of quantum mechanics: first, that protective measurements show that the wave function describes an individual physical system; second, that the system described by a wave function is best understood in terms of a set of particles moving randomly and discontinuously in three-dimensional space; and third, that this random, discontinuous particle motion provides new tools for solving the measurement problem via a collapse theory.
