We try to give a physical meaning to the wave function or quantum state of a system, apart from being a very efficient tool for predicting results of measurements on that system. In other words, we ask: what does it mean for a system outside the laboratories to have a wave function? We first explain why two possible, and probably common, answers to that question do not really answer it. Then, we explain how the de Broglie-Bohm theory does give a satisfactory meaning to the quantum state outside the laboratories, while avoiding the problems faced by the other answers.
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