Shift of Spectral Lines Due to Dynamic Multiple Scattering and Screening Effect : Implications for Discordant Redshifts

The frequency shift of spectral lines from astronomical objects is most often explained by the Doppler Effect arising in relative motion and the broadening of a particular line is supposed to depend on the absolute temperature , pressure or the different line of sight velocities.. The Wolf effect on the other hand deals with correlation induced spectral changes and explains both the broadening and shift of the spectral lines. In this framework a sufficient condition for redshift has been derived and when applicable the shift is shown to be larger than broadening. Under this condition of larger shift than broadening we find a critical source frequency below which no spectrum is analyzable for a particular medium. This gives rise to new type of sreening effect which may play significant role both at laboratory scale as well as in the astronomical domain. We apply a simple interpretation of the discordant redshifts in galaxy-quasar associations.