The Real Puzzle behind Special Relativity (2)
When talking about the universe,
some authors compare the stars and planets to the dust in the air.
Taking the fact that the closest star beside the Sun is several light years away from us,
we can see that description is not an exaggeration.
The Sun has been sending out light since its birth,
so does all the other stars in the universe.
Where did all the light go? Maybe a tiny fraction was absorbed by the celestial bodies,
but most of them just got lost in the vast space.
Does not this lost light form a natural medium for light?
The constant propagation speed of light can be best explained by the vibration of the medium.
Among all the tiny particles, like atoms, neutrons, protons, and electrons,
which of them always run at the same speed? If light is composed of photons,
why are photons so special and always run at the same constant speed?
Does not the existence of a medium relieve the photons from such a difficult duty?
Suppose the medium of light does exist,
then the postulate about light in Special Relativity will be much easier to understand.
It is this medium that decides whether a reference frame is stationary or not.
Does the existence of this medium give Special Relativity any validity?
Let's go to the next section and see.