So. Immagin a train in front of you. Your standing under the blue sky staeing foward at the box car. Under the boxcar you see shiny metal tracks that seem to go on forever. The box car is at a halt, parked in front of you. You open the huge sliding doors and see a mirror on the floor. You also see one on the seeling perfectly parelel to the on one thefloor. You then see a beam of light. You notice the light going perfectly up and down bouncing between the mirrors. Each time the light goes up and back down, one second has gone by. This is a great way to measure time you thinkto yourself as you observe the slow moving light. Then a hobo jumps on the train answer sits in the corner. The train starts to move foward. As it gains speed you notice the light bounce to the left a little. The hobo sees it bounce up and down perfectly though. Since it bounced to the left a little, it took longer to reach the other mirror, so that second was a little slower to you compared to the man on the train. As the train gets faster and faster the light seems to bounce further to the left relative to you. Then the train reaches light speed and you notice the light seems to have stoped in the middle and is now traveling in the middle of the mirrors paralel to them. Time is now frozen to you relative to the man on the trian. This is how i understand relativity... the longer the light between the two mirrors the longer the time for the guy on earth. The problem is.... dont I have it backwords???