eng Science and Education Publishing International Journal of Physics 2333-4576 2016-08-13 4 5 123 129 10.12691/ijp-4-5-2 IJP2016452 article Xiao Lin Li hidebrain@hotmail.com 1 Chongqing, China There exist a new physics model. Real physical world is 5-dimensional space-time. Human world is 4-dimensional space-time. Human world just is the projection of real physics world. Particle wave is present in 5-dimensional space-time. So we can derive out Mass-energy equation. So we can derive out all results of Special Relativity Theory. In 5-dimensional space-time, speed of all particles is the light speed c. It is reason that the light speed c is very special. Coordinates transformation in 5-dimensional space-time, can derive out Lorentz transformation. The new physics model theory is a equivalent theory with Special Relativity Theory. In 5-dimensional space-time, there only exist space expansion or space contraction. In 5-dimensional space-time, there not exist time expansion or time contraction, time is absolute. In 5-dimensional space-time, particle rest mass only is particle movement portions at 4th dimensional space. The new 5-dimensional space-time theory, is consistent with space-time system of Special Relativity Theory, and it can transition to space-time system in Lorentz symmetry breaking smoonthly. The new 5-dimensional space-time theory has more wide range adaptation than Special Relativity Theory. http://pubs.sciepub.com/ijp/4/5/2/ijp-4-5-2.pdf de Broglie wave particle wave Special Relativity Theory mass-energy equation 5th dimension 4th dimensional space 5-dimensional space-time the Light speed Particularity of the light speed The source of particle rest mass Lorentz symmetry coordinates transformation Lorentz transformation Lorentz symmetry breaking equivalent theory with Special Relativity Theory