  Weyl's scale invariance is introduced as an additional local symmetry in the
standard model of electroweak interactions. An inevitable consequence is the
introduction of general relativity coupled to scalar fields a la Dirac and an
additional vector particle we call the Weylon. Once Weyl's scale invariance is
broken, the phenomenon (a) generates Newton's gravitational constant G_N and
(b) triggers the conventional spontaneous symmetry breaking mechanism that
results in masses for all the fermions and bosons. The scale at which Weyl's
scale symmetry breaks is of order Planck mass. If right-handed neutrinos are
also introduced, their absence at present energy scales is attributed to their
mass which is tied to the scale where scale invariance breaks. Some
implications of these ideas are noted in grand unification based on the gauge
symmetry SU(5).
