  We investigate the recent suggestions by Barausse et al. (astro-ph/0501152)
and Kolb et al. (hep-th/0503117) that the acceleration of the universe could be
explained by large superhorizon fluctuations generated by inflation. We show
that no acceleration can be produced by this mechanism. We begin by showing how
the application of Raychaudhuri equation to inhomogeneous cosmologies results
in several ``no go'' theorems for accelerated expansion. Next we derive an
exact solution for a specific case of initial perturbations, for which
application of the Kolb et al. expressions leads to an acceleration, while the
exact solution reveals that no acceleration is present. We show that the
discrepancy can be traced to higher order terms that were dropped in the Kolb
et al. analysis. We proceed with the analysis of initial value formulation of
general relativity to argue that causality severely limits what observable
effects can be derived from superhorizon perturbations. By constructing a
Riemann normal coordinate system on initial slice we show that no infrared
divergence terms arise in this coordinate system. Thus any divergences found
previously can be eliminated by a local rescaling of coordinates and are
unobservable. We perform an explicit analysis of the variance of the
deceleration parameter for the case of single field inflation using usual
coordinates and show that the infrared divergent terms found by Barausse et al.
and Kolb et al. cancel against several additional terms not considered in their
analysis. Finally, we argue that introducing isocurvature perturbations does
not alter our conclusion that the accelerating expansion of the universe cannot
be explained by superhorizon modes.
