  Model independent arguments following from the Covariant Entropy Principle
imply that causal diamonds in the very early universe were entirely filled with
a single equilibrated system with finite entropy. A universe where this
condition persists forever has no localized excitations. Our own universe
appears to be headed toward such a state. Within a few hundred times its
current age it will approach a state where our local group of galaxies sit in
empty de Sitter space. Eventually, the local group collapse into a black hole,
which evaporates. Localized excitations in de Sitter space are low entropy
constrained states of the vacuum ensemble. The origin of these constraints must
be in the early universe: the apparent horizon must expand after some initial
period, in a constrained state that is the origin of all localized excitations
in the universe. We argue that in global FRW coordinates, this corresponds to
slow roll inflation that ends in a dilute gas of tiny black holes, with mass
determined by the inflationary scale. We then review arguments that these black
holes can account for the Hot Big Bang, baryogenesis, a distinctive pattern of
CMB fluctuations, and possibly primordial black hole dark matter consisting of
larger black holes that survive until the matter dominated era. The more
complicated question of whether these small black holes can evolve in a way
that is consistent with all observational constraints requires computer
simulations that have not yet been done.
