Wolf effect

The Wolf Effect (sometimes Wolf shift) is a frequency shift in the electromagnetic spectrum.^[1] The phenomenon occurs in several closely related phenomena in scattering of light.^[2] It was first predicted by Emil Wolf in 1987 ^{[3] [4]} and subsequently confirmed in the laboratory in acoustic sources by Mark F. Bocko, David H. Douglass, and Robert S. Knox,^[5] and a year later in optic souces by Dean Faklis and George Morris in 1988 ^[6]. Wolf and James noted:

"Under certain conditions the changes in the spectrum of light scattered on random media may imitate the Doppler effect, even though the source, the medium and the observer are all at rest with respect to one another.^[7]