  In previous work, we showed that the answer to the question posed in the
title cannot be found within an equilibrium setting. The inclusion of {\em
dynamical} backreaction effects from massive long wavelength modes on the
initial DeSitter patches results in gravitational instabilities that cleanse
the phase space of inflationary initial conditions of all regions except those
allowing high energy inflation. This interplay between the matter and
gravitational degrees of freedom explains why ergodicity is broken and why the
Universe starts in an out-of equlibrium state with low entropy. Here we argue
that this reduction of the phase space of inflationary initial conditions
implies that an inflationary universe is incompatible with holography inspired
proposals such as causal patch physics and D (N)-bounds. We also discuss why
chaotic or eternal inflation may not resolve the puzzle of the initial
conditions and of the arrow of time.
