  The entropy of the observable universe is increasing. Thus, at earlier times
the entropy was lower. However, the cosmic microwave background radiation
reveals an apparently high entropy universe close to thermal and chemical
equilibrium. A two-part solution to this cosmic initial entropy problem is
proposed. Following Penrose, we argue that the evenly distributed matter of the
early universe is equivalent to low gravitational entropy. There are two
competing explanations for how this initial low gravitational entropy comes
about. (1) Inflation and baryogenesis produce a virtually homogeneous
distribution of matter with a low gravitational entropy. (2) Dissatisfied with
explaining a low gravitational entropy as the product of a 'special' scalar
field, some theorists argue (following Boltzmann) for a 'more natural' initial
condition in which the entire universe is in an initial equilibrium state of
maximum entropy. In this equilibrium model, our observable universe is an
unusual low entropy fluctuation embedded in a high entropy universe. The
anthropic principle and the fluctuation theorem suggest that this low entropy
region should be as small as possible and have as large an entropy as possible,
consistent with our existence. However, our low entropy universe is much larger
than needed to produce observers, and we see no evidence for an embedding in a
higher entropy background. The initial conditions of inflationary models are as
natural as the equilibrium background favored by many theorists.
