Within present constraints on the observed smooth energy and its equation of state parameter w _ { Q } = P / \rho _ { Q } , 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 a = 1 / 1 + z .
We are optimistic about distinguishing between a cosmological constant and appreciably dynamic quintessence , by measuring average values for the effective equation of state parameter w _ { Q } ( a ) .
However , reconstructing the quintessence potential from observations of any scale dependence w _ { Q } ( 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 \mathcal { R } _ { 0 } \sim 2 .
Identifying this collapsed fraction as a conditional probability for habitable galaxies , we infer that the prior distribution is flat in \mathcal { R } _ { 0 } or \Omega _ { m 0 } .
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 quasistatic quintessence potentials .