  The currently available values and confidence limits for Omega_m0, H_0 and
globular cluster ages still indicate that the dark energy that dominates the
Universe could also be a form of quintessence or phantom energy. In fact,
current cosmological values favor phantom energy. To increase the likelihood of
a cosmological constant as dark energy instead of phantom energy, the
possibilities seem to lie in reducing globular cluster ages, the Hubble
constant, or both, and possibly advancing the epoch of globular cluster
formation. For a set of possible dark energy equations of state that includes
the cosmological constant, quintessence or phantom energy, age-redshift
analytical expressions for null curvature universes that include ordinary
matter are derived together with the corresponding ages for these universes.
