So I am relatively (pun intended) new to the world of Special and General relativity and trying to reconsile what I read with what makes sense in my head (apparantly probably the biggest hurdle to this whole area.) I took several physics courses in college, but they were your very standard Newtonian physics classes, and relativity was discussed very little. One issue I am having is due to the following hypothetical experiment that I thought up the other day. Please correct me if I go astray, and if I do not, please explain how this fits in to the STR: Say you have a train car 10m long. On the cieling and floor of said train car are mirrors. For the sake of the experiment, lets say the mirrors perfectly reflect light, and there is no glass to change the speed of light reflecting off the mirrors. The sides of the train car ar clear so they can be seen through. On one end of the train car is a laser angled at such an angle that it's x-component (parallel to the track) is 1m/s, and it's z component(non-normal, othogonal to the track) is 0 (a very very small angle, I know.) The end of the car opposite where the laser is being fired is open. Now on the train is one observer, and off the train is another observer. The train is moving at a speed of 1 m/s in the direction of the x component of the laser, and the outside observer is stationary relative to the train. Now, since both observers outside and inside the train see the light traveling at c, and c is not effected by the speed at which the train is moving, won't the observer inside the train see the light exit the car after 10 seconds, and the observer outside the car NEVER see the light exit the train? (to him, the light is traveling in the direction of the track at the same speed as the train is moving.) How is this reconsiled with STR?