Before Einstein, scientists knew that ‘the laws of physics are same in all inertial reference frames’.
From Maxwell’s experiments on electromagnetic fields, it became clear that Light travels at a speed of 3×108 m/sec. Einstein had rightly taken this point and restated the above as “laws of physics including speed of Light (SOL) remain the same in all inertial reference frames”.
Then began all the wrong interpretation-
There wouldn’t have been any confusion if the statement had just meant- ‘Maxwell’s equations predict the same SOL in any inertial reference frame’ but Einstein’s special relativity preaches an entirely weird thing- A flash of light travels at the same speed relative to any observer, irrespective of the motion of the observer or the source.
Though the mistake is immediately evident, it definitely needs a lot more elaboration because the absurd predictions of relativity are deeply engraved into the minds of the scientists and the public.
Let us compare the law of constant speed of light and the Newton’s first Law in two inertial reference frames-
In the inertial reference frame B, Newton’s first law predicts that a ball moving at 10kmph continues to move at the same steady velocity in the absence of external force. But it doesn’t say that the ball moves at the same steady velocity of 10kmph with reference to an observer in frame B. Obviously the ball moves at 30kmph according to the observer in frame A.
Similarly, if Maxwell’s equations predict that a flash of light travels at 3×108m/sec in frame B, it doesn’t mean that the light flash travels at the same speed with respect to an observer in frame A.
When a ball’s velocity is not constant to different observers, why should a light photon’s velocity remain the same? Maxwell’s equations didn’t predict that the SOL is constant to differently moving observers.
So there is no reason at all to assume that speed of light is constant to all the observers. Of course this is what commonsense tells us but relativists abandoned this long ago in favour of weird mathematical predications.