Ok. I admit I'm completely new to Relativity (I had my first lecture today!). What I learnt was that the speed of light is a absolute constant that doesn't change. I then came into some situation like, 1. I'm driving my car with velocity v and turn on my headlights, won't the speed of light coming out of my headlights be c+v? 2. If light speed is absolute constant, then the index of refraction would always be 1 when light goes from one medium to the other cuz index of refraction is the ratio between the speed of light in two different media. Someone plz explain.