Einstein's Theories   Einstein states that a ray of light is C and it has a speed of 299792458 km/sec but if the ray of light was measured with in a confined area say like a train then the speed of light would still be the same. If there was an observer on the outside of the train with a velocity of V he would see the speed of light at C0 = (C^2 - V^2)^1/2. But no matter where the experiment is held, the speed of light will always be the same in that specific context. http://www.spaceart.org Now to interate how time plays with the equation of the speed of light, dt = dt' . (1-v^2/C^2)^1/2. In this formula dt is the time that passes when you move at a speed of v, dt' is the time that passes when you stand still, and C is the speed of light. http://www.ebay.com