4-D homogeneous isotropic cosmological models generated by the 5-D   vacuum
  4-dimensional homogeneous isotropic cosmological models obtained from solutions of vacuum 5-dimensional Einstein equations are considered. It is assumed, that the G(55)-component of the 5-d metric simulates matter in the comoving frame of reference. Observable 4-d metric is defined up to conformal transformations of the metric of 4-d section \tilde{g}, with a conformal factor as a function of the component G(55). It is demonstrated, that the form of this function determines the matter equation of state. Possible equations of state are analyzed separately for flat, open and close models. 
Yu.S.Vladimirov, S.S.Kokarev