There's the problem. You suppose wrong. The fact that we've observed single particles interfering with THEMSELVES is the basis of quantum theory. You're not going to understand any of these comments until you realize that. It *doesn't make sense* but it's *proven fact anyways* because we've seen it. Einstein didn't like it either, and it's a screwy concept for everyone. Reality doesn't make sense. The fact that the two theories we've developed to explain it best are at odds with eachother is the biggest problem in modern physics. Things like photons are waves and particles at the *same exact time*. Generally speaking, the interaction between radiation (with or without mass) and spacetime is decidedly wavelike, and its interaction with matter is decidedly particulate. Forcing interaction with matter collapses the wavelike nature of radiation both directly and through entanglement.
I don't expect you to comprehend this, no one can yet-- but do you understand it?