On the invariance of the speed of light
  The invariance of the speed of light in all inertial frames - the second postulate of special theory of relativity (STR) - is shown to be an inevitable consequence of the relativity principle of special theory of relativity taken in conjunction with the homogeneity of space and time in all inertial frames, i.e., the 1st postulate of STR. The new approach presented here renders the learning of special theory of relativity logically simpler, as it makes use of only one postulate. 
Harihar Behera and Gautam Mukhopadhyay
physics.pop-ph