The Postulates of Special Relativity (4)
Comparing with the first postulate (about physical laws), the second one (about light propagation) is not so easy to understand.
The difficulty is not in the constant speed of light,
as this fact is a common knowledge to all of us.
The source irrelevant part is also easy to understand.
As light is a kind of wave, it should behave like any other wave,
whose propagation speed is not affected by the source.
But what does the "stationary" mean? Which one is this stationary reference frame?
It cannot be the Earth, as the Earth is in a high speed motion.
It cannot be the "Ether" either, because Einstein specifically rejected it in his paper.
As I cannot think of any such stationary reference frame,
here I assume that this stationary reference frame is any one.
Or in other words, every reference frame is "stationary".
So, the second postulate can be stated this way:
Light travels at the same constant speed in all reference frames.
In this paper, fundamental wrong ideas are highlighted in dark red.
Combining the two postulates, we can see two types of objects in the universe.
The first type is all objects in Newtonian mechanics, which follows the rule of relative motion.
The second type is light, which does not follow the rule of relative motion.
So, Special Relativity is the mixed result of these two types of objects.
Remember how hard our teachers tried to explain that there is no
absolute rest in the universe?
After all of us seem to have been convinced that all motions are relative,
here we find an absolute motion of constant speed c.
Don't our teachers feel a little sad?