Original sentence: The Wolf Effect (sometimes Wolf shift) is a phenomenon in radiation physics that manifests itself as a frequency shift in the electromagnetic spectrum.Under certain conditions, the shift may be distortion free, Wolf and James write:
Edited sentence: The Wolf Effect (sometimes Wolf shift) is a phenomenon in radiation physics that manifests itself as a redshift or blueshift in the electromagnetic spectrum.Under certain conditions, the shift may be distortion free, and hence indistinguishable from the so-called Doppler, cosmological and gravitational redshifts.Wolf and James write: