BIANCHI TYPE-I COSMOLOGICAL MODELS IN HIGHER DIMENSIONS

In the present paper Krori and Barua's work on Bianchi type I solutions in (9 + 1)-dimensional spacetime has been extended for viscous as well as perfect fluid in general (D + 1) dimensions. The Hubble functions are expressed in terms of the ratio (σ2/θ2), and explicit solutions are obtained in several special cases for viscous fluid involving both bulk and shear viscosities. The perfect fluid with the equation of state p = p is also discussed in (D + 1) dimensions and is found to have properties of dimensional reduction analogous to those in vacuum found by Krori and Barua. It is further observed that effective four-dimensional entropy would considerably increase if rapid contraction of extra dimensions takes place.