  We explore how the thermal ground states of two mixing and pure SU(2)
Yang-Mills theories, SU(2)$_{\tiny\mbox{CMB}}$ of scale
$\Lambda_{\tiny\mbox{CMB}}\sim 10^{-4}\,$eV and SU(2)$_{e}$ of scale
$\Lambda_{e}\sim 5\times 10^5\,$eV, associate either wave or particle aspects
to electromagnetic disturbances during thermalisation towards the photon gas of
a blackbody, in realising the photoelectric effect, and through the frequency
dependence of the monochromatic, nonthermal beam structure in Thomson/Compton
scattering.
