Perturbations on time dependent Orbifold Singularities

Abstract

We start with the standard time-dependent backgrounds such as the geometry and dynamics of Freidmann-Robertson-Walker(FRW) cosmologies. First, we discuss the dynamics and geometry of FRW cosmologies. Then we introduce perturbations on this FRW cosmologies. We then study more exotic orbifold spacetimes and examine their symmetries. We examine how those symmetries determine the partition functions on such symmetrical spacetimes.