Theory of “Relativity of speed of light with speed of universe expansion” explains relation of speed of light with speed of universe expansion. This theory provides an evidence that the time cannot be relative as stated by Theory of General Relativity. Theory of Special Relativity and Theory of General Relativity were based on two fundamental propositions i.e. constancy of speed of light and independence of physical laws (especially the constancy of speed of light) from the choice of inertial system. However, postulate of these theories is not correct. Theory of “Relativity of speed of light with speed of universe expansion” answers fundamental propositions i.e. constancy of speed of light and independence of physical laws in logical manner. This theory also explains real reason behind E = mc².