Solution to the measurement problem based on Belavkin's theory of Eventum Mechanics. There is only Schrödinger’s equation and a unitary evolution of the wave function of the universe, but we must add a Heisenberg cut to separate the past from the future (to separate particles from waves): Belavkin’s eventum mechanics. The past is a commuting sub-algebra A of the algebra of all observables B, and in the Heisenberg picture, the past history of any observable in A is also in A. Particles have definite trajectories back into the past; Eventum Mechanics defines the probability distributions of future given past. https://arxiv.org/abs/0905.2723 Schrödinger's cat meets Occam's razor (version 3: 10 Aug 2022); to appear in Entropy