
The Six-Dimensional World
In order to define relativistically invariant field functions, fields are defined as unitary irreducible representations of the Poincaré group. When the carrier space for these representations is taken to be ordinary Minkowski space-time, the resulting fields are spinors. It is possible, however, to obtain scalar-valued wave functions with non-trivial spin spectra by selecting as carrier space larger homogeneous spaces of the Poincaré group, Minkowski space being just such a homogeneous space of that group.
In order to construct such fields with an isospin spectrum within this approach, it is necessary to consider unitary irreducible representations of groups larger than the Poincaré group but which include it as a subgroup.
The quantum field theory developed in the previous paper is shown to correspond, in the non-relativistic limit, to a deformable elastic sphere model.
It is shown how current String Theories are obtained as a limiting case of the Sphere Theory developed here.