Coupling of gravity to matter viaSO(3, 2) gauge fields

We consider gravity from the quantum field theory point of view and introduce a natural way of coupling gravity to matter by following the gauge principle for particle interactions. The energy-momentum tensor for the matter fields is shown to be conserved and follows as a consequence of the dynamics in a spontaneously brokenSO(3, 2) gauge theory of gravity. All known interactions are described by the gauge principle at the microscopic level.