Quintessence Cosmology and the Cosmic Coincidence

Within present constraints on the observed smooth energy and its equation of state parameter $\dub=P/\rhoq$, it is important to find out whether the smooth energy is static (cosmological constant) or dynamic (quintessence). The most dynamical quintessence fields observationally allowed are now still fast-rolling and no longer satisfy the tracker approximation if the equation of state parameter varies moderately with cosmic scale. We are optimistic about distinguishing between a cosmological constant and appreciably dynamic quintessence, by measuring average values for the effective equation of state parameter. However, reconstructing the quintessence potential from observations of any scale dependence $\dub(a)$ appears problematic in the near future. For our flat universe, at present dominated by smooth energy in the form of either a cosmological constant (LCDM) or quintessence (QCDM), we calculate the asymptotic collapsed mass fraction to be maximal at the observed smooth energy/matter ratio. Identifying this collapsed fraction as a conditional probability for habitable galaxies, we infer that the prior distribution is flat. Interpreting this prior as a distribution over theories, rather than as a distribution over unobservable subuniverses, leads us to heuristic predictions about the class of future quantum cosmology theories and the static or quasi-static nature of the smooth energy.