The photon doesn't know that it's alive and its dead. So we have to come to a deeper understanding of how to explain what is going on in this double slit experiment. And not only these other particles, but o ther universes in which these particles exist. This is where the concept of interference comes in. Interference is an old concept in physics. It goes back to waves. Waves certainly interfere, but we need to understand the way in which particles can interfere one with another.