  In order to solve this problem, the orthodox theory postulates that in measurement interactions, entangled states of measured systems and the corresponding measurement apparatuses do not evolve according to the Schrödinger equation. Rather, they undergo a ‘collapse’ into product (non-entangled) states, where the systems involved have the relevant definite properties. For example, the entangled state of the particle pair and the L-apparatus in the EPR/B experiment may collapse into a product state in which the L-particle comes to possess z-spin ‘up,’ the R-particle comes to possess z-spin ‘down’ and the L-apparatus pointer displaying the outcome z-spin ‘up’: