The most important postulate in Special Relativity is the principle of invariant light speed. According to Einstein, any ray of light moves in the “stationary” system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body.
It implies that for example even for an imaginary light source moving with speed of .01*C in one direction, the emitted light ray in the opposite direction will travel with the speed of C and not 0.99*C in the moving reference frame. If this assumption is invalidated, the Theory of Special Relativity will fall and all the story about contraction of relative time-space will come to an end.
My question is why this assumption holds. What is the ground for it? Even if Einstein was right, what is the justification for it?
I have read few papers arguing this principle such as "Light speed invariance is a remarkable illusion" by Stephan J.G. Gift, but still no paper in reputable journals.
Ahmadreza Eslami This is a very good question and I do think it is important to be able to visualise what is actually going on and why.
I will try to explain what is happening in the context of the Spacetime Wave theory.
Data Prerecording of Conference Presentation on the Unification of Physics
You will see from this presentation that light propagates as a wave disturbance of Spacetime. Now contrary to the initial assumption of Special Relativity, we do know that there is a rest frame in the universe called the CMB rest frame.
We can suppose that when light is emitted it is released into this rest frame of the universe and travels at speed c in this rest frame. Now this does not invalidate the conclusions of SR that there is an equivalence between moving frames of reference because the rest frame is just one of many possible frames of reference.
Given the nature of protons, neutrons and electrons as looped waves in Spacetime we can see that moving at velocity v relative to the rest frame will result in a length contraction right down at the level of the individual atomic particles.
This length contraction will then result in a measurement of the speed of light as c when the measurement is made in the moving frame of reference.
So although SR is derived assuming that there is no unique rest frame the conclusions are valid even though there is a unique rest frame.
Richard
Richard Lewis Hi Richard,
There are two contradictions in your answer. First, light can travel in vacuum and doesn't need any material to travel through.
Second and more importantly, space contraction is an outcome and result of the Special Relativity and cannot be used to justify the assumption.
Ahmadreza Eslami No contradictions. We are not talking about a material but a medium for transmission. Space is indeed a vacuum. It is universally agreed that Spacetime is the medium for the transmission of gravitational waves. I am saying that Spacetime is also the medium for the transmission of light waves.
Second point. It is not space that is contracting. The length contraction of a measuring rod for example is a correct conclusion from the theory of Special Relativity. What I am explaining in the Spacetime Wave theory is the cause of the length contraction.
Richard
Richard Lewis Well without measurement, there is no sense of space. So, we perceive any contraction in space through contraction in the variable values and measurements!
Ahmadreza Eslami Yes, but we have to go with what the theory is telling us. It tells us that space is expanding at a constant rate corresponding to around one part in 14 billion per year. So space doesn’t contract.
Objects moving with velocity v through space do contract in length.
Richard
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