You are in a spaceship that is not moving in any direction. You are facing forward, so in the direction of the ships nose (and direction of flight when it moves). In front of you, a couple of meters away, there is a mirror attached to the wall. You have a flashlight in your hand. You turn it on and point it at the mirror. The light takes t to travel from the flashlight to the mirror and back to you again. The spaceship now accelerates to 50% c and then maintains a constant speed. You are still in the same spot when you turn the flashlight on and point it at the mirror once again. How long does the light take to travel from the flashlight to the mirror and back to you again ? - t - 1.5t< - 2t And why ? Also, what would prevent light to travel at c relative to the flashlight ?