The Formalism of Quantum Theory: An Objective Description of Reality?

We argue that the formalism of quantum theory can be given an empirical interpretation (in the sense of a connection with observable phenomena) in the same way as in any other empirical theory. In particular, there is no need to supplement the unitary time evolution governed by a Schrödinger‐type of equation with a “projection postulate” that applies only to measurements. As a consequence, the quantum formalism has the same status as the formalisms of older physical theories, and is capable of the same philosophical interpretations. The most natural interpretation, we argue, is to conceive of the formalism as an objective – although highly abstract – description of reality.