be a Hermitian operator with nondegenerate eigenvalues \(\sigma_j\), and let \(\ket{w^j}=\ket{s^j}\). Then the measurement outcome \([m^j]\) corresponds to measuring the eigenvalue \(\sigma_j\)—see the remarks in subsection 3.3—and \eqref{eqn29} and the remarks following it justify assigning to the particle at time \(t_2\) the ket \(\ket{w^j}=\ket{s^j}\). One may add that the more general form of wave function collapse embodied in the Lüder’s rule (Busch &amp; Lahti 2009) is likewise a consequence of the general quantum principles governing stochastic time development set forth in section 4, so need not be added as an additional hypothesis.