  A consistent theory of free tachyons has shown how tachyon neutrinos can
explain major cosmological phenomena, Dark Energy and Dark Matter. Now we
investigate how tachyon neutrinos might interact with other particles: the weak
interactions. Using the quantized field operators for electrons and tachyon
neutrinos, the simplest interaction shows how the chirality selection rule, put
in by force in the Standard Model, comes out naturally. Then I wander into a
re-study of what we do with negative frequencies of plane wave solutions of
relativistic wave equations. The findings are simple and surprising, leading to
a novel understanding of how to construct quantum field theories.
