New time dependent wave solutions to the classical homogeneous Maxwell equations in the vacuum have been found. These waves are not transverse; they exhibit both torsion and spin; they have finite magnetic helicity, a nonzero Poynting vector, E x H and a non zero second Poincare invariant, E dot B.
Two four component rank 3 tensors, constructed on topological grounds in terms
of the Fields and Potentials, are used to define the concepts of torsion and
Spin, even in domains with plasma currents. The divergence of the spin pseudo
vector generates the Poincare invariant equivalent to the Lagrangian of the
field, B dot H D dot E(A dot J  rho phi). The divergence of the Torsion
pseudo vector generates the second Poincare invariant, E dot B. The Poincare
invariants have closed integrals which are deformation invariants, and therefore
can be used to define deformable coherent structures in a plasma. When the
second Poincare invariant is nonzero, there can exist solutions that are not
timereversal invariant.
