On the Role of Quantum Events in Double-Slit Experiments

We formulate the Schr"odinger equation as the equation of motion of a small external influence which serves as the initial boundary condition of a physical system in classical laboratory space. The Hilbert space of possible external influences for a given physical system is then equivalent to the Hilbert space of a quantum system without spin. We discuss the double-slit experiment in the context of this approach and show that wave-particle dualism reduces to the choice of a basis in the geometrical construction of the Hilbert space of small external influences.