The theory of classical electromagnetism is constructed in terms of two exterior
differential systems, FdA=0, and JdG=0, which act as topological constraints
on the variety of independent variables {x,y,z,t}. These two fundamental
constraints lead to two other independent concepts of topological torsion, A^F,
and topological spin, A^G, which are explicitly dependent upon the potentials,
A. The exterior derivative of these 3forms creates the two familiar Poincare
deformation invariants of an electromagnetic system, valid in the vacuum or
plasma state. When the Poincare invariants vanish, the closed integrals of A^F
and A^G exhibit topological invariant properties similar to the 'quantized'
chiral and spin properties of a photon. The possible evolution of these and
other topological properties is studied with respect to classes of processes
that can be defined in terms of singly parameterized vector fields. Nonzero
values of the Poincare invariants are the source of topological change and
nonequilibrium thermodynamics.
Published in Poincare Group, Photon, V. Dvoeglaz editor
