Original Post
This experiment is one of the best demonstrations of the acausal and quantum nature of reality. Look, when you look at something which is black, there's no light there. No matter how you rotate it. There are no even photons which cancel each other. When you add the third polarizer, what happens is the "photonic nature" of reality becomes directly observable, showing that photons are the edges of the connection field, (photons don't "experience" time and space). Photons form the very fabric of spacetime. And causality is only our experience.