I've been thinking about this for some time now and I wanted to get some feedback on it. If photons are supposed to travel along straight lines (for the sake of simplicity lets neglect the curvature of space-time), then how could one photon possibly be used in a double slit experiment? More specifically, how could one photon traversing a straight line possibly create an interference pattern with itself? I have never heard of even pseudo-logic that would allow for something this absurd. I understand that upon absorption (or some other event) the possible paths of the photon will "reduce" to a single path that takes it, in essence, in a straight line from emission to absorption; I'm not concerned with the reduction part of it, I'm concerned with the "all possible paths" that we assume the photon to be traversing simultaneously. What possible logic could then say that the photon travels along a straight line, and why do we still teach that this is the case? If we're saying that the photon travels along an infinite number of straight lines, simultaneously, during the time between absorption and emission, that would make sense, but every single day I have to struggle with the fact that different sources explain the propagation of light in different ways. If I'm reading about optics, I'm going to get the "photons travel in straight lines" interpretation. If I'm reading about pure quantum physics, I'm going to get a completely different story, where photons are evolving over multiple paths simultaneously, until they reduce to having traveled a single path. If one is true, the other is not. Which one is it?