I was really proud of the way this turned out. The materials on the rods and cones changes in the light. In the dark, the rods are almost completely transparent, and the nuclei are all pink. In the light, I have a top/bottom material where the bottom is purple/transparent, and the top is pink. The cones I did a little differently. In the light, their texture is a simple gradient, but in the dark, they have a noisy shadow. Not sure how well you can see it in the video - and because how short my short is, I don't think anyone's going to notice how much thought and work I put into these.
I animated the material on the lightbulb to become more transparent, but in the scene, it ends up so bright, you can't even really tell. But it is there!
I animated the material on the white pawn that interacts with the photon. They bounce off the surface - reflecting back to us, so we see a white chess piece. The reason we see different colors is because some photons are absorbed and some are reflected. A red cup absorbs all other colors and reflects red (or at least it reflects photons that affect the red color-receiving cones in our eyes).
I also animated the material on the black pawn that interacts with the photon. It's the same concept. My short in general becomes more saturated as it progresses, symbolizing the interaction of light with our eyes. First, we pick up on lights and darks, then we pick up on color differentiation. It's all stuff I learned from Abbott Smith in Bio 100: Visual Perception.
