Let's compare the basic steps of their thoughts with a ball game. Children throw a ball into the air and try to catch it again. A children's game that we do not pay special attention to. Now they try to play the same game in an open car that crosses the country road. If the speed is too high, the game will no longer succeed. The ball is caught by the wind and falls to the ground behind the car. Exactly this result was expected by the scientist Michelson and Morley during their attempt.
Instead of the speed of the car, they use the rotational speed of the earth around the sun. The airstream was in their case the world ether and in place of our ball they set a beam of light which was reflected by a mirror again. The attempt failed. The speed of light was the same in every direction. There was no airstream coming from the ether. Either the world ether moved in a kind of vortex with the earth or there was no world ether.
The experiment was discussed violently in physical circles, because the results showed slight deviations, which could not be explained. Was it just a measurement error or is there something else behind it? The Dutch physicist Hendrik Antoon Lorentz suspected that all matter in the direction of motion had to contract due to deformations in the atomic range the closer it approaches the speed of light, which is why the deviation in Michelson's experiment also occurred.
According to Hendrik Antoon Lorentz's calculation, a rod of one meter shrinks by about the length of an atom at an Earth orbit speed of 30 kilometers per second. The Lorentz contraction, as it is called, is undisputed today. But what the light wave carries and whether it is a wave at all or a particle or something completely different, that is still unclear today.
The mechanistic view of the world of physicists begins to shake when a man no one had heard of before spoke up. In 1905, a third order scientist, Albert Einstein, who had found his way out of the Bern patent office, submitted his hypothesis to the experts, which he called the "principle of relativity" and which later went down in the history of the natural sciences as a special theory of relativity.
Einstein's basic assumption goes back to Faraday's findings that the movement of a magnet near a wire loop generates an electric stream in it. Albert Einstein made it clear that it did not matter whether the magnet was moved or the wire loop, the result was exactly the same. It only depended on the relative motion of the two objects. If we transfer this example to our field of experience, we lack an optical reference system. So we are not able to determine who or what is moving, we only determine the relative motion of the objects to each other.
Part 2 
Part 4 
