On the constancy of the velocity of light

We point out that the acceptance of the relativity principle together with the homogeneity and isotropy of space and the homogeneity of time inevitably leads to the Lorentz spacetime transformation with a universal limiting speed . Speculations on possible new four-dimensional symmetries involving a variable speed of light such as that proposed by Hsu must therefore be dismissed on such a basis alone. In this paper we draw attention to some logical inconsistencies in Hsu's attempt at establishing a new space-light transformation law, and follow with a discussion on why such an attempt must necessarily fail.