Hah, nice! Looking at it now, of course it makes sense. I guess I just short-circuited by thinking of the polarizer as blocking light only, and not that the red

Hah, nice! Looking at it now, of course it makes sense. I guess I just short-circuited by thinking of the polarizer as blocking light only, and not that the reduction in intensity is the result of the projection of the previous wave direction onto the new wave plane! EDIT: not that this makes the quantum effects any clearer ;)