A phenomenological model for the calculation of reduction probabilities of a superposition of several states is presented, which bases only the idea that quantum state reduction has its origin in a physical interaction between the states. The model is explicitly worked out for the hypothesis of gravity-induced quantum state reduction. It agrees for typical quantum mechanical experiments with the projection postulate and predicts regimes in which other behaviour could be observed. For verification a feasible quantum-optical experiment is proposed. An outlook on the possible role of state reduction for biology is given by exemplarily discussing mutation effects of bacteria.
We propose a mechanism for time reparametrization symmetry breaking in canonical gravity. We consider a model of spinor gravity, based on Sen's reformulation of canonical gravity as a spin system, with one additional long-range self-interacting massive spinor particle that is coupled to spinor gravity. The symmetry breaking is identified with the origin of the quantum mechanical non-unitary evolution. A part of our approach to deriving non-unitary time-dependent processes of wave functions follows the Diosi-Penrose argument on gravity's role in quantum state reduction.