  Discussed is the classical theoretical description of the experimentally
established thermal redshift of spectral lines. Straightforward calculation of
the observable spectrum from a canonical ensamble of monochromatic radiators
yileds overall blueshift rather than redshift. It is concluded that the
customary explanation of the thermal redshift as a second order Doppler effect
does not bear closer examination, and that in fact, the phenomenon ''thermal
redshift'' is not yet fully uderstood in classical terms.

Quantum Physics