| A bystander watches a moving light clock oriented perpendicular to the direction of motion pass by.
When light travels the length of the clock, it ticks.
(Imagine this tick of the clock to be a human heartbeat of the person carrying the clock.)
Why does the bystander conclude that the moving clock (heart) is running slow? Click here to see an animation of the Light Clock). (WARNING: A fairly fast computer is required for best viewing. You can do this exercise without watching the animation, but you will find it helpful to review first the illustrations in the textbook.) |