The Physical Reality of the Quantum Wave Function

Abstract

By examining a particular thought experiment, we show that two observers, outside of “each other’s light cone”, when examining the same quantum system, will ascribe very different quantum wave functions to that system. Nevertheless, both observers will agree on the statistical distribution of all observations performed upon the system. Thus the quantum state of the system does not appear to possess an invariant objective status. We conclude from this example that the quantum wave function which describes the state of the system under observation is observer dependent. Therefore it is reasonable and consistent to regard the wave function as but a convenient algorithmic device enabling observers to predict the response of quantum systems to observations. We briefly apply this point of view to demystify the well-known problem of Schrödinger’s Cat.