  A gauge theory of quantum gravity is formulated, in which an internal, field
dependent metric is introduced which non-linearly realizes the gauge fields on
the non-compact group $SL(2,C)$, while linearly realizing them on $SU(2)$.
Einstein's $SL(2,C)$ invariant theory of gravity emerges at low energies, since
the extra degrees of freedom associated with the quadratic curvature and the
internal metric only dominate at high energies. In a fixed internal metric
gauge, only the the $SU(2)$ gauge symmetry is satisfied, the particle spectrum
is identified and the Hamiltonian is shown to be bounded from below. Although
Lorentz invariance is broken in this gauge, it is satisfied in general. The
theory is quantized in this fixed, broken symmetry gauge as an $SU(2)$ gauge
theory on a lattice with a lattice spacing equal to the Planck length. This
produces a unitary and finite theory of quantum gravity.
