Most people with exposure to any physics learn some basics about electrons, light and quantum mechanics, but I think it is tough to put these different ideas to

Most people with exposure to any physics learn some basics about electrons, light and quantum mechanics, but I think it is tough to put these different ideas together. The hard part about quantum mechanics for physicists is not the rules for quantum mechanics but how that manifests itself in the real world. This is how I have understand it. I'll talk about electrons first. An electron is a point particle. The position of the electron is governed by a wave (wave function). The wave is not made out of "electron". It is made out of something else, kind of like "probability". The wave tells you where you find the electron. But when you do find the electron, it is always a point particle. You will never detect the electron smeared out over space. (As an aside, for those who think about field theory, I still see the electron as point in field theory, though some might see it differently.) Light is a field/wave made of the electric field. And it has a wave function too. The wave function again is made of probability. But it is probability for different electric field configurations, rather than photon locations, so it might be harder to picture. Why does a light behave like a particle at all? Though the light has spatial extent it does come in discrete chunks, specific quanta of energy. When light is absorbed it can only be absorbed in these discrete quanta. In most detectors (like photographic paper) the light is absorbed by an electron. Since the electron is a point particle, the photon absorption happens at a single point. This might make it look as if a "particle" of light hit the detector.