  Structure factor theory (SFT) is applied to analyze distortions to the Cosmic
Microwave Background Radiation (CMBR) due the Sunyaev-Zel'dovich Effect (SZE)
in typical clusters of galaxies. It is shown that a suitable structure factor
associated to a collisionless (Knudsen) gas is able to reproduce the SZE
distortion of the CMBR . Physical arguments suggest that SFT yields an
approximate solution to the Kompaneets equation and sets plausible values for
the two ``free'' parameters involved in the calculation of the spectral
distortion. Finally, further applications of the SFT to other standard
cosmological problems are briefly discussed.
