  Investigations of dense neutrino cloud evolution through quantum kinetic
equations led to the possibility of ``fast flavor" (FF) processes. It is shown
here that the usual quantum kinetic equations, while signaling the
instabilities that make some instances of FF possible, are being erroneously
interpreted. Approaching the subject directly from the quantum field theory
that defines the standard model shows the computational structures in most of
the recent FF literature to be completely invalid. Our revisions also underlie
what promise to be new early universe applications and a general result for
relic supernova neutrinos that could be tested as a feature of the diffuse
neutrino spectrum.
