The Cause of Self-Contradiction (1)
Maybe you have doubt on my analysis of the second postulate, and will raise these questions:
- How do we interpret the result of the Michelson-Morley experiment?
- Does the propagation of light need a medium? Where is that medium?
These questions are not easy to answer.
But luckily, to disprove Special Relativity, we do not need to answer any of them.
The concept of relative motion is the key to our problem!
The swimmer's speed has several readings. Relative to the water, it is c; relative to the bank, it is c-v when going upstream, and is c+v when going downstream. These different speeds are the direct results of relative motion.
If light travels at the same speed in all reference frames, you can never see light's speed as c-v or c+v, no matter which reference frame you are in.
So the first equation of Special Relativity is about relative motion.