  It has recently been shown that the observed Hubble function for cosmological
expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with
only one free constant, while neglecting cosmic curvature and mass, using the
modified Friedmann equation implied by subjecting the Higgs scalar field model
to conformal Weyl scaling symmetry. Time-dependent solutions of the
relativistic conformal Higgs scalar field equation coupled with the conformal
Friedmann equation are shown here to imply dark energy of the observed
magnitude. Predicted persistent cosmic acceleration is consistent with the
nonclassical parameter inferred by conformal theory from observed excessive
galactic rotation velocities and galactic dark halos, all without dark matter.
