It appears to me that all are averse to discuss the question I raised
for fear of shaking fundamental aspect of SR. So I would like to make
my argument.
I do not wish to discuss here, whether light is ballistic or not. If
light is ballistic then it would behave like a ball and so even for
light all inertial frames would be equivalent. But in that case, MMX
needs no explanation and there is no need for SR.
In case light is not ballistic, then inertial frames are not
equivalent and it is easy to detect motion of any frame based on
absolute velocity of light. But in this case detected velocity of
light would be c+v and c-v. In this case too SR will have to be
dumped.
Some illustrious posters have argued that there is no difference in
the frames. This is true in terms of relativity. However a passenger
can always perform the experiment, while stationary and then after
accelerating to some constant velocity. Problem with relativity is
that it doesn’t deal with such a reality. Of course stationary
observer will easily detect this velocity but actually this is not
necessary. Based on knowledge, a passenger can find out if light is
ballistic or not. If it is ballistic then he will not be able to
detect his own uniform motion.
Some have argued that, SR is based on two postulates. However
postulates cannot ignore known facts. Extraordinary postulate can be
made in case of unknown. For example postulate of ether to explain
wave nature of light. But ether was rejected as it would require
abnormal properties. Here we are dealing with something within our
knowledge of something and that which can be proved. A very small
pulse of light can be generated and it does have finite velocity in
space. Once we know this, there is no other way but to treat this
pulse as a bunch of photons. It is madness to treat light as both
Maxwell’s wave and photon simultaneously.
The only question remains is that of nature of light which gets itself
propagated at a constant velocity. Whether it is source independent or
not has no relation to the postulates. If light is ballistic then
Einstein’s 2nd postulate is wrong and if it not then his 1st postulate
is wrong.