Why speed of light of is constant?

Second postulate of Einsteins relativity (invariance of c)

As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body.

I tried to find out why is this so, at many places on internet. But, all I got to know is that by experiments it is confirmed that "c" is always constant. But, if you go through my below post, you will understand that this not something that is special about light.Even with materials, the same behavior gets exhibited. It just some unique way that "distance lag" and "inertia" balance each other. If this is true, it will need some fundamental change in our understanding of Einstein's relativity. We will know why speed of light is constant irrespective speed of frame of observer and many flush out concepts of insanity like time travel, conversion of material into energy, black holes, singularity before big bang etc.

Consider below picture








There are two objects A and B moving away from each other. We will consider a universal frame of reference here , marked with numbers. But, as you know such a frame does not exists. That means it is not possible to know if A is fixed and B is moving or B is fixed and A is moving or both are moving in the same direction with different velocities or both of them moving away from each other.

First, let us assume that there is universal frame is available. With respect to universal frame of reference A is stationary and B is moving with velocity "v" away from A. Now, assume that a canon on object fires a ball with velocity "c" towards A. A will receive the ball with velocity "c-v".
This is basically because of inertia of ball. The inertia is property of it mass.

Now, in absence of universal frame it is not possible to determine if A is fixed and B is moving away from A. So, let us assume other extreme of the scenario and let us analyze it with respect to reference frame. In the other case, B could be constant and A could be moving away from B. In this particular case, canon ball travels with velocity "c-0" i.e. "c". But, by the time it reaches at the place of A, A is moved further. When it reaches new position of A, A still moves little further. The extra distance that canon ball has to cover makes it approach with slower velocity at A. How much? it finally make it slower to the velocity "c-v". Refer my post on series in this same blog.

This is very interesting for two reasons.
1. irrespective of which object is fixed , finally ball is received at A is at (c-v). So, in absence of universal frame of reference the universe remains balanced.

2. In the first case inertia or mass was the reason for slower velocity. In second case the reason is time or distance gap. So actually, inertia and distance gap complement each other perfectly to maintain balance or make universal frame of reference unnecessary. This is very interesting. Mass and distance are two totally different characteristics but still they complement each other.

Now, if some thing is mass less, it will not have any inertia. So instead of canon ball, if B flashes light ray in first case, it will immerse with velocity "c". But, then in second case how does it can not produce distance lag?

Einstein took help of time. He though time is relative it flexes to make sure that velocity remains "c" in second case in spite of distance lag. But, I do not think so. See my post "is time relative" on my blog.

I guess, there is nothing like mass less in this universe. So speed of light is constant is an assumption it self is baseless.