  In this paper we specifically studied one aspect of foreground primordial
matter density perturbations: the relative gravitational time delay between a
pair of light paths converging towards an observer and originating from two
points on the last scattering surface separated by the physical scale of an
acoustic oscillation. It is found that time delay biases the size of acoustic
oscillations {\it systematically} towards smaller angles, or larger harmonic
numbers $\ell$, i.e. the mean geometry as revealed by CMB light becomes that of
an open Universe if $\Omega=1$. Since the effect is second order, its standard
deviation $\delta\ell/\ell \sim (\delta\Phi)^2$ where $(\delta\Phi)^2 \sim
10^{-9}$ is the normalization of the primordial matter spectrum $P(k)$, the
consequence is too numerically feeble to warrant a re-interpretion of WMAP
data. If, however, this normalization were increased to $\delta\Phi \gtrsim
0.01$ which is still well within the perturbation limit, the shift in the
positions of the acoustic peaks would have been substantial enough to implicate
inflationary $\Lambda$CDM cosmology. Thus $\Omega$ is not the only parameter
(and by deduction inflation cannot be the only mechanism) of relevance to the
understanding of {\it observed} large scale geometry. The physics that explains
why $\delta\Phi$ is so small also plays a crucial role, but since this is a
separate issue independent of inflation, might it be less artificial to look
for an alternative solution to the flatness problem altogether?
