the multi-verse theory doesn't seem explain the wave behavior though. how is it that an infinite number of universes would interact with one another all at once?

when unobserved, the photon would have to exist in every possible position w.r.t. time in order to interfere with itself and behave as a wave. in this scenario, ALL of the universes involving the experiment would have to be affecting one another, all existing at once; this is hard to understand/believe. in order to detect a photon you would have to interact with it somehow, like all things. i think that the method of detection might play a big role.

seize the day