eng Science and Education Publishing International Journal of Physics 2013-09-16 1 1 106 109 10.12691/ijp-1-5-2 IJP2013152 article Zhiliang Cao williamcao12252000@yahoo.com 1 Henry Gu Cao 2 J.P.Morgan Chase Deerfield High School, Deerfield A constant one-way light speed is essential for the Theory of Relativity. This detailed study examines two postulates of Special Relativity and concludes that the claim of “constant one-way speed of light” contradicts itself. The equations of Special Relativity are foundations of many physics theories. The findings on controversial Relativity postulates shake the foundation of these theories. Fortunately, equations similar to Special Relativity equations can be derived, assuming that two-way light speed is constant, without the use of Special Relativity Postulates. These new equations provide a better foundation that is compatible with the correct existing physics theories. There is no threat of invalidating all existing physics theories, only incorrect ones. Instead, we can take a new look at some fundamental questions shared among physicists. http://pubs.sciepub.com/ijp/1/5/2/ijp-1-5-2.pdf relativity physics unified theory one-way speed of light