There is a transactional analysis interpretation (Ref. 6), most frequently applied to situations in which photons are involved, in which the source emits waves that travel forward in time and the ‘target’ emits waves which travel backwards in time. These two waves together determine the probability that a ‘photon’ will travel on one path or another. However, because there is No Evidence for the Existence of Particles , including photons, this interpretation cannot be justified. Also any scheme in which the probability law is obeyed must be non-linear (see Mathematical Collapse Implies Non-Linearity), and it is not obvious where non-linearity is introduced into the transactional analysis interpretation.