  Testable predictions of quantum mechanics are invariant under time reversal.
But the change of the quantum state in time is not so, neither in the collapse
nor in the no-collapse interpretations of the theory. This fact challenges the
realistic interpretation of the quantum state. On the other hand, this fact
follows easily if we interpret the quantum state as a mere calculation device,
bookkeeping past real quantum events. The same conclusion follows from the
analysis of the meaning of the wave function in the semiclassical regime.
