Who hasn't heard about the **double-slit experiment**? It figures in any book of quantum physics. But there is something no one can explain to me: I understand why the light cannot be described only as a wave, but I do not understand why it cannot be explained only in terms of a particle, having some trajectory, following other laws of physics we may not know. Usually, every book in which I have tried to look for an answer considers that if it cannot be described as a **classical** trajectory (which is clearly the case in this experiment), then it is not a particle, that is, a material point. Could it not be a particle following new laws?