  It is a mystery why the density of matter and the density of vacuum energy
are nearly equal today when they scale so differently during the expansion of
the Universe. We suggest a paradigm that might allow for a non-anthropic
solution to this cosmic coincidence problem. The fact that the half life of
Uranium 238 is very near to the age of the solar system is not considered a
coincidence since there are many nuclides with half lives ranging over a huge
range of time scales implying that there is likely to be some nuclide with a
half life near to any given time scale. Likewise it may be that the vacuum
field energy causing the universal acceleration today is just one of a large
ensemble of scalar field energies, which have dominated the Universe in the
past and then faded away. Given that in standard cosmology and particle physics
there are already several scalar fields that probably contribute to universal
vacuum energy (the Higgs field, the inflaton, and whatever quintessence/dark
energy field causes the current acceleration), the idea of a large ensemble of
fields does not seem far fetched. Predictions of the idea include: 1) The
current vacuum energy driving the acceleration is not constant and will
eventually fade away, 2) The ratio w of scalar field pressure to density is
currently changing and is not precisely negative one, 3) There were likely
periods of vacuum dominance and acceleration in the past, 4) the current phase
of acceleration will end but there may be additional periods of acceleration in
the future, 5) the ultimate fate of the Universe cannot be decided until the
nature of these fields is known, but the eventual sum of densities from all
scalar fields could be zero, as was usually assumed before the discovery of the
current universal acceleration.
