  Not all complete set of spinors can be used as expansion coefficients of a
quantum field. In fact, Steven Weinberg established the uniqueness of Dirac
spinors for this purpose provided: (a) one paid due attention to the
multiplicative phases for each of the spinors, and (b) one paired these to
creation and annihilation operators in a specific manner. This is implicit in
his implementation of the rotational symmetry for the spin half quantum field.
Among the numerous complete set of spinors that are available to a physicist,
Elko occupies a unique status that allows it to enter as expansion coefficients
of a quantum field without violating Weinberg's no go theorem. How this
paradigm changing claim arises is the primary subject of this communication.
Weinberg's no go theorem is evaded by exploiting a uniquely special feature of
Elko that allows us to introduce a doubling of the particle-antiparticle
degrees of freedom from four to eight. Weinberg had dismissed this degeneracy
on the ground that, "no examples are known of particles that furnish
unconventional representations of inversions." Here we will find that this
degeneracy, once envisioned by Eugene Wigner, in fact gives rise to a quantum
field that has all the theoretical properties required of dark matter.
