  While complicated, unreliable alternatives to Doppler effect were proposed,
an elementary optical light- matter interaction provides one which is commonly
observed in the labs, but with a distortion due to the use of short, powerful
laser pulses. It is generally assumed that Raman scattering in gases is
incoherent. This assumption fails if the pressure is lowered enough to increase
the relaxation times over the length of light pulses; the ''Impulsive
Stimulated Raman Scattering'' (ISRS), generally used to study dense matter with
ultrashort laser pulses, is adapted to the low energy pulses making the
incoherent light beams; the usual light is redshifted by some very low pressure
gases while it propagates.
  To produce this adapted ISRS called ''Incoherent Light Spatially Coherent
Raman Scattering" (ILSCRS), a molecule must have an hyperfine structure:
polyatomic molecules must be heavy or have odd numbers of electrons; light
atoms and the other molecules must be perturbed by a Stark or Zeeman effect.
  ILSCRS redshifts may be distinguished from Doppler redshifts using a very
difficult to observe dispersion of ILSCRS redshifts. This dispersion may
explain the discrepancies of the fine structures in the spectra of the quasars,
presently attributed to a variation of the fine structure constant.
  While the present interpretation of the Lyman forest in the spectra of
quasars requires clouds stressed, for instance, by sheets of dark matter,
ILSCRS interpretation requires only usual physical concepts. It produces
thermal radiations from short wavelengths, just as dust.
