The speed of light is constant in all inertial frames of reference.
I've just begun studying relativity and my question is rather elementary.
Well, Einstein did consider this postulate as the basis for his theory but my intuition says something slightly different.
I tried to get to this postulate given that the Theory is true. The latter says that it is impossible to travel at $c$, and as I keep increasing my speed, it becomes more and more difficult to accelerate myself and I end up travelling only at a fraction of $c$(let's say…$c/1000$? although this is practically unfeasible too).
Well, couldn't we say that in my frame, the speed of light(assuming that it's travelling in the same direction as I am), I witness the photon travelling at $\frac{999}{1000}c$. But that's almost as good as $c$!
My point is, what if the second postulate is a result of the fact that one can hardly reach such speeds, so this approximation always comes out to be almost $c$?Have I thought of this correctly?Or have I got it all wrong?
Best Answer
"[W]hat if the second postulate is a result of the fact that one can hardly reach such speeds [...]?" But the second postulate doesn't depend on such thought-experiments. Nor was it very strongly supported by real experimental evidence at the time Einstein proposed it. It was a bold postulate that, together with the Relativity Principle, generated a new kinematics and dynamics, cleared up several perplexing issues in electromagnetism in a most elegant way, and made many radical predictions that have been born out by experiment. That's why most physicists accept the truth of the second postulate!