When he was first thinking about relativity (and before he developed his theory), Einstein considered how the universe would look to a person who traveled on a light beam. Suppose you are traveling on a light beam when you encounter a friend who is traveling on a second light beam in the opposite direction. What is your friend\'s speed relative to your reference frame? (Express your answer in terms of c and use the postulates of special relativity to find the correct answer.) Solution According to special relativity, the speed of light is same in all reference frames. So even though i am watching my friend(moving with c) from a frame which is itself moving with c(me), my friend\'s speed relative to my reference frame would be c(speed of light). .