Einstein utilized Lorentz invariance from Maxwells equations to modify mechanical laws and establish the special theory of relativity. Similarly, we may have a different theory if there exists another covariance of Maxwells equations. In this paper, we find such a new transformation where Maxwells equations are still unchanged. Consequently, Veselagos metamaterial and other systems have negative phase velocities without double negative permittivity and permeability can be described by a unified theory. People are interested in the application of metamaterials and negative phase velocities but do not appreciate the magnitude and significance to the spacetime conception of modern physics and philosophy.