ProWave makes no assumption of localization of the photons before measurement. In fact, it rejects the common notion of wave-particle duality. Recent teaching by laser physicist W.E. Lamb Jr. supports this line of thinking . Maintaining any sort of particle nature of elementary quanta is what has led us into trouble, philosophically. Let's start with a list of the assumptions made in the ProWave Interpretation:
Assumption (2) deals with propagation, which is a nonlocal, wavelike phenomenon, and Assumption (3) deals with the creation and destruction of quanta, which is a local phenomenon. These assumptions eliminate the ambiguity of what the electrons and photons do while we don't measure them. They are quantum waves: Electrons orbiting atoms are standing waves of matter-energy, photons are wavepackets of electromagnetic energy, etc. Also, we accept that a photon passes through both slits if both are probable and it was not already absorbed by the wall. The same goes for electrons. In this way, we can reinstate physical reality which is dismantled in any wave-particle duality interpretation. The physical reality is simply that described by the wavefunctions and density matrices of a system, no matter how quantum entangled the states may be. It may be difficult to imagine the states in classical terms, but they are states nonetheless in which these very simple elementary quanta can exist. And they propagate according to the laws described by the mathematics of quantum mechanics.
As the quanta propagate and interact with the macroworld, two separate types of interactions occur. The first is defined as a partial interaction: This interaction reorganizes or redirects the wavefunction designated by a unitary transformation matrix. Examples of such are beamsplitters and magnetic fields. The other type of interaction is defined as a complete interaction: This is designated by the destruction (and creation) of a quantum of energy, for example a bound electron absorbing a photon.
Before applying ProWave to the experiments described earlier, here it's quickly shown that ProWave can add insight into how a cloud chamber can measure the particle-like nature of matter waves. As, say, an electron traverses its ``path'' in the cloud material, it is constantly being forced into localized positions by partial interactions with the material. Thus, the matter wave is being reorganized constantly and not really allowed to diffract much before collapsing repeatedly. The result is a clearly drawn path that was previously believed that only a particle could make.
The ultimate challenge for ProWave is to explain how a spread-out wave can collapse and deliver its energy locally upon absorption. It is helpful to envision wave evolution analogous to blowing up a balloon. Upon measurement, that balloon pops. The collapse (also pertains to reconfiguring the wave's energy) is probabilistic, like not knowing where a balloon will pop first. But once a measurement has been taken (or perhaps the quantum is destroyed) the wave collapses everywhere nonlocally and passes its energy to the absorber as one quanta. Likewise, when a balloon pops, the entire surface of the balloon is quickly affected by the loss of tension in the rubber, however time elapses before the surface collapses. This collapse (for the quantum) need not be instantaneous, but must be faster-than-light to insure that nonlocality still applies. The phenomena of energy absorption and reconfiguration (quantum state changes) are inherently quantum uncertain events and cannot be pinned to ``instantaneous''- only for practical purposes do we assume so. This is not a problem physically because the nature of this collapse is very poorly understood. In fact, I am suggesting the possibility of a more general theory that reduces to QM when the time of the collapse is considered small, in the same way that QM reduces to classical mechanics under certain conditions. This is typically the way physics advances; I don't see this potential for the other, far less intuitive, interpretations.