Vacuum cosmological solution in a 6D universe

A simple vacuum cosmological solution that is a function ofct, Gm/c ² andeG ^1/2/C² is obtained in the 6D space-time-mass-charge universe which is proposed by Wesson 1] with the introduction of the sixth coordinate of charge in order to obtain a unified theory of gravity and electromagnetism along the line of his original 5D space-time-mass universe 2]. It reduces to a similar solution to that of the radiation era in the 4D FRW universe through the compactifications of the extra dimensions. The trajectory of a test particle in the 6D universe is also studied by using the solution.