A CLASS OF MULTIDIMENSIONAL COSMOLOGICAL MODELS AND ITS POSSIBLE ASTROPHYSICAL CONSEQUENCES

Assuming a homogeneous matter-energy content such that p = p(t) and d = d(t) we have obtained exact solutions for cosmological models in higher dimensions under different symmetries. Depending on the form of metric chosen the models are either uniquely Robertson-Walker-like in higher dimensions or differ significantly from the latter in the sense that the geometry is spatially inhomogeneous. The explicit time dependence of the scale factor is calculated in some of the cases via the assumption of an equation of state p = md (m is a constant). Spatial geometry as regards singularity, astrophysical parameters like "decelaration factor," entropy, and time-temperature relation of the universe are also calculated. Utilising one of the solutions an expression for luminosity distance function is found in higher dimension and it is observed that the deSitter spacetime sets an upper limit to the absolute distance of any cosmological source, where the generally accepted value of q ≥ -1 is taken. Further, some remarks of general nature are made about nucleosynthesis in higher dimensional world with the help of time-temperature relation and it is conjectured that dimensionality may have significant impact, in principle at least, on the phenomenon of nucleosynthesis. However, it may be too premature to come to any definite conclusion in this regard at this stage. © 1992.