Does the theory of relativity depend on the speed of light in vacuum or in air?
  EINSTEIN’S RELATIVITY: Everything in the universe is traveling through space-time at the speed of light – the maximum speed possible. If you are sitting still in space, then you are traveling through time at the maximum speed. But if you begin traveling through space, then your progress through time slows down. Time Dilation and other relativistic phenomena await you in this interesting series, so hurry up and slow down!