 Before concluding this section some comments about the measurement process are of relevance. Quantum theory was created to describe the behavior of microscopic phenomena as was emerging from observations. In order to obtain information about system at the molecular and (sub-) atomic scale, one must be able to establish strict correlations between the states of the microscopic system and the states of the measuring devices, which we directly perceive. Within the formalism, this is described by considering appropriate micro-macro interactions. The fact that when the measurement is completed one can make statements about the outcome is accounted for by the already mentioned WPR postulate (Dirac 1935): a measurement always causes a system to jump in an eigenstate of the observed quantity. Correspondingly, also the statevector of the apparatus ‘jumps’ into the manifold associated to the recorded outcome.