If that is the case then why we always state second postulate before writing E=mc2.
Secondly because of this second postulate we are further proving time dilation, lengh contraction ... So now my qeustion is can we still prove Time dilation theory (if second postulate is wrong).
As we know very famous equation E= mc2
While deriving this equation there are two postulates
Postulate I:
The laws of physics are the same in same in all inertial frames.
Postulate II:
The speed of light (in a vacuum) has the same constant value c in all inertial frames.
If we...