Evolution of Bulk Scale Factor in Warped Space-time
  In this work the role of extra dimensions in the accelerated universe through
the scenario of higher-dimensional Friedmann-Robertson-Walker (FRW) cosmology
has been studied. For this purpose, we first consider warped space-time in the
standard flat brane scenario as the modified form of Robertson-Walker (RW)
metric in five-dimension (5D) space-time and then the variation of the bulk
scale factor (warp factor), with respect to both space-like and time-like extra
dimensions is obtained. Finally, it is shown that both of two types of extra
dimensions are important in this scenario and also the bulk scale factor plays
two different roles.
