Einstein Showed That Time Is Relative. But … Why Is It?

No, not 20 m / s. The ball moves in 30 m / s (ie 10 + 20). A lot of common sense. The difference is a movement of different “reference frames” and the other is different from the stationary.

All is well, although; Everyone agrees to the conclusion. If the ball hits a person, the wrong unhappy and bystander will calculate the effective time at the same time. Yes, people in the car moving the ball in a slower speed, but they are moving towards them, so they do the same.

This is the other major postulat of special relativity: physics is the same for all reference frames, or the same to be specific to all “inertial” or accelerated frames. Observers can move at different speeds, but these speeds should be constant.

In any case, you can now see that the speed of light is the same for all observers, regardless of the speed of the light.

Waves in an empty sea

How did Einstein get this crazy idea? I will show you two reasons. First, light is an electromagnetic wave. The physicists have been treated like a light wave for a long time. But there is a need for waves environment inside for “wave” inside. Ocean waves require water; The sound waves require air. Exit the middle and no wave.

But then, what environment did the sunlight pass through space? In the 1800s, many physicists believed to be an environment in space and called him Luminiferics Aether Because it’s fun to say.

In 1887, Albert Michelson and Edward Morley prepared a smart test to reveal this Aeter. A mixture of a mixed beam is a device called an interferometer and closed the same length along the two ways, the mirrors bounce and re-combine in a detector:

Illustration: Rhett Allan