We know matter/energy creates a gravitational field. But energy can be carried away from a system of orbitting bodies in the form of gravitational waves. So if gravitational fields can carry away energy (gravitational wave), then the gravitational field has an energy density in and of itself independent of matter and radiation. It this is so, then can the gravitational field be augmented by its own energy density to an even greater gravitational field? Could this explain dark matter? Thanks.