these wheels roll, roll from here out, this wheel gets out first, it starts going faster so it just unbends, okay? so what happens, this light over here, the waves of light, okay, will now kinda come like this, bend like that, see what i mean? and over here, a place over here, rays of light come in all direction, maybe light coming like that, bends like this, a person's eye is right here. a person's eye looks out and sees root beer all along the edge. it's an illusion. the root beer is really in here. if the light didn't change speed going from here to here, then you would see the thickness of the glass. i saw a very, very neat thing one time. i saw a bottle of coca-cola. and the bottle of coca-cola was embedded in a piece of plastic. so it turns out that the light wouldn't change speed very much going from the glass to the plastic, and when you look at that, you can see the coke like this. and you could get a better representation of the true volume of the coke, do you know what i'm saying? do you know what i'm saying, okay? but when you take this out on the air, boom, there's a big change