This is an excellent intuitive treatment. The speed of light is constant. So if Al, moving with respect to you, shines a light up to a mirror in his spaceship the distance the light travels for him is just up and down. Because Al is moving away, you see the light following a longer path. Since the speed of light in constant Al's clock must record a smaller time that your clock where light travels a greater distance to make distance /time constant.
Simultaneity is relative for events that do not occur in the same place. If you are equidistant from two lights and they flash you will see each light at the same time but someone who is moving toward one of the lights will see it first.
Spacetime, with three space and one time dimension provides an accurate representation. By analogy we can measure dimensions of a three-dimensional book using different two-dimensional views from photos that give different lengths and widths. Your frame of reference is different. There is an invariant spacetime distance.
No comments:
Post a Comment