On a possible ground state for quantum gravity

A variational calculation is presented of the ADM-energy of the quantized g ravitational field around a wormhole solution of the classical Einstein's e quations. One finds the energy of such state to be in general lower than th e perturbative ground state, in which the quantized gravity field fluctuate s around flat (Euclidean) space-time. As a result the strong indication eme rges that a gas (or a lattice) of wormholes of Planck mass and average dist ance l(p), the Planck length, may be a good approximation of the Ground Sta te of Quantum Gravity, some implications of which are reviewed.