Late-time Cosmic Acceleration from Compactification
  We investigate the implications of energy conditions on cosmological
compactification solutions of the higher-dimensional Einstein field equations.
It is known that the Strong Energy Condition forbids time-independent
compactifications to de Sitter space but allows time-dependent
compactifications to other (homogeneous and isotropic) expanding universes that
undergo a {\it transient} period of acceleration. Here we show that the same
assumptions allow compactification to FLRW universes undergoing {late-time}
accelerated expansion; the late-time stress tensor is a perfect fluid but with
a lower bound on the pressure/energy-density ratio that excludes de Sitter but
allows accelerated power-law expansion. The compact space undergoes a
decelerating expansion that leads to decompactification, but on an arbitrarily
long timescale.
