  In the first part of this talk we review some prerequisites for and essential
arguments involved in the construction of the thermal-ground-state estimate for
the deconfining phase in the thermodynamics of SU(2) Quantum Yang-Mills theory
and how this structure supports its distinct excitations. The second part
applies deconfining SU(2) Yang-Mills thermodynamics to the Cosmic Microwave
Background in view of (i) a modified temperature-redshift relation with an
interesting link to correlation-length criticality in the 3D Ising model, (ii)
the implied minimal changes in the dark sector of the cosmological model, and
(iii) best-fit parameter values of this model when confronted with the spectra
of the angular two-point functions TT, TE, and EE, excluding the low-$l$
physics. The latter, which is treated in an incomplete way because of the
omission of radiative effects, is addressed in passing towards future work.
