In physics, we often think of light as being a wave that can transfer energy. If we bounced the ray back into the light source, what type of quantifiable effect could there be on the light, and how do we measure/compute that? In lecture, it was mentioned in the case of a sun, light wouldn't be able to bounce off, but how would we treat other cases?
In lecture, Professor Ng also mentions that we can usually think of the light source as a light bulb or some sort. And since a light bulb is made of glass, it also bounces light as other glass-made surfaces do. If I interpret it correctly, I assume we can treat it as just yet another object in the scene that bounces light.