Vacuum structure in quantum gravity

The physical interpretation of the Eguchi-Hanson (EH) instanton solution is suggested. This solution describes the tunneling transition which connects vacua with opposite orientations. The diagonal vacuum states are symmetric and antisymmetric superpositions of states with a given orientation. The EH instantons lead to appearance of the induced Einstein term and of the large induced cosmological term in the effective action of the conformal gravity theory. (orig.)