The description of neutrino propagation through a fluctuating medium is
summarized. Fluctuation-Dissipation-Theorem arguments relate microscopic
fluctuations to thermodynamic quantities, allowing these to be very generally
studied in astrophysical environments.
Fluctuation-induced modifications to neutrino oscillations have been studied
in detail within the Sun and within the envelope of supernovae, and although
surprisingly large effects have been found none appear to be observable in the
near future.