The Five-dimensional Space - Time - The Qualitative Theory Of The Dirac Equation And Variable Rest Mass

In this paper, fistly the traditional Kaluza-Klein theory and the variable-gravity theories based on Mach principle are briefly reviewed. Space-Time-Matter theory, namely modern Kaluza-Klein theory, is summarized in detail.Then the induced-matter theory proposed by Wesson and Liu is emphatically introduced, and the Wesson-Liu method is commented on and generalized.After that, According to the induced-matter idea, we study the generalizational method of 5D Dirac equation, and point out that Dirac equation isn't formally generalized in principle because the wave function of Dirac field is multiple component matrix form. We introduced a rest mass operator in 5D flat space, find the proper relation between 5D Dirac matrix and 4D Dirac matrix, generalize the Dirac equation to the cured space, and obtain the general expression of the effective induced matter. We check our results for the two specific cases of the static, spherically-symmetric gravity and the 5D cosmological solution which we obtain corresponding to the 4D close Roberston-Walker cosmological model, which are satisfactory in the sense that the results embody the spirit of Mach principle and have no conflict with observations on astrophysics.