Why Does Diffraction Produce Rainbows? Quantum Electrodynamic Reflection

In our world, Quantum Mechanics doesn’t really play a noticeable role. This is how it managed to remain hidden for so long in our scientific quest of discovering the universe. In our world most laws and theories seem to work to perfection. It’s only in very unique cases where Quantum mechanics is the only way to adequately explain what is happening. Diffraction is a phenomenon that is easily explained by wave interference. Light of course is a wave so why wouldn’t this be the case? But what happens if you send only one photon at a time? Surely then there’s no interference. Like it or not, even when sending one photon at a time you discover strange phenomenon that do not traditionally make sense. They only make sense if you truly accept how bizarre our world is. Source: QED: The Strange Theory of Light and Matter