Can We Go The Speed Of Light?

About this video

Einstein's train of thought.

Whether you are in a car, on a plane, or in a room, the world feels the same. This is because as long as we are moving in a frame of reference with constant speed, the laws of physics apply in exactly the same way. This concept is known as Einstein's principle of relativity.

Derek Muller demonstrates a classic thought experiment by the famous physicist. If you were on a train that is travelling at the speed of light and you held a mirror in front of you, would you see your reflection?

To see your reflection, light has to bounce off your face and onto the mirror at the speed of light. But if the mirror is travelling at the speed of light, how will the light ever catch up?

Einstein concluded that you would see your reflection, but that light must travel at the same speed inside and outside the train. Through these complex mental gymnastics, he changed our view of the speed of light from something seemingly relative, to a true universal constant.