A cosmological solution of a 5D space-time-mass gravity in vacuum

A cosmological solution is obtained in a 5D space-time-mass cosmological model by applying a homogeneous and isotropic metric, whose tensorsg_ij(i, j =0–4) are functions of both timet and massm, to the field equations in vacuum. It shows that in this theoryg₄₄of the fifth coordinate is contracted not only by special functional form oft as in the Kaluza-Klein theory but also by that ofm. This procedure realizes the universe which evolves into a conventional 4D radiation-dominated era from a 5D vacuum era.