Kennedy Bennett

From Your Perspective – Kennedy Bennett

The formulas for time dilation and length contraction are embroidered on the front of the shirt. On the back there is a train traveling at half the speed of light, Observer B (indicated by the letter ‘B’) riding the train and shining a light toward a mirror inside, and Observer A (indicated by the letter ‘A’) is standing off on the side.
Simultaneity: The image shows the relativity of simultaneity through the lightning bolts on both sides of the train; if lightning strikes both ends of the train equi-distance from A, then A will see both strikes at the same time. By the time A sees both flashes, B has already moved past. As B moves at half the speed of light, it will first see the lightning strike at the front of the train (closest to him) followed by the strike at the end of the train (further from it).
Time Dilation: If B shines a light on the mirror, the observer will simply see the light traveling straight to the mirror and back. A will also see the light travel to the mirror and back, but the observer also saw it while the train was moving. So, A will see the light travelling diagonally. From A’s perspective, the light traveled a greater distance. To compensate for the greater distance Sally perceives, time elongates.
Length Contraction: Observer B would interpret the length of the train to be 100m while Observer A would see the train as ~87m. s