Klein, In The Modern The Kaluza --- Klein Theory Of Gravitation --- Gordon Equation And Variable Rest Mass,

In this paper, it is reviewed briefly that the traditional Kaluza---Klein theory and the variable gravity theory based on Mach principle . Then the modem Kaluza---Klein theory , namely five-dimension Space-Time-Mass theory , is summarized in detail and the simple comment is given After that, we emphatically study generalization of Klein---Gordon equation in this framework, and point out that there are the necessity and possibility to make further generalization and improvement in the minimally coupled case which is discussed by Professor Liu Hongya etc At last , we raise the confonnally invariant Klein---Oordon equation in Kaluza---Klein theory , and give particularly several typical solutions as well as expression of variable mass.