Electromagnetic waves and photons

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.