A new 8-dimensional conformal gauging avoids the unphysical size change,
third order gravitational field equations, and auxiliary fields that prevent
taking the conformal group as a fundamental symmetry. We give the structure
equations, gauge transformations and intrinsic metric structure for the new
biconformal spaces. We prove that a torsion-free biconformal space with exact
Weyl form, closed dilational curvature and trace-free spacetime curvature
admits a sub-bundle of vanishing Weyl form homeomorphic to the Whitney sum
bundle of the tangent bundle and the bundle of orthonormal Lorentz frames over
4-dimensional spacetime. Conversely, any 4-dimensional spacetime extends
uniquely to such a normal biconformal space. The Einstein equation holds if and
only if the biconformal basis is orthonormal. Unconstrained antisymmetric trace
of the spacetime curvature provides a closed 2-form, independent of the Weyl
vector, consistently interpretable as the electromagnetic field. The trace of
the spacetime co-torsion decouples from gravitational sources and serves as
electromagnetic source.Comment: 32 pages, plain TeX, no figure
