A quantum gravity theory which becomes renormalizable at short distances due
to a spontaneous symmetry breaking of Lorentz invariance and diffeomorphism
invariance is studied. A breaking of Lorentz invariance with the breaking
patterns SO(3,1)→O(3) and SO(3,1)→O(2), describing 3+1 and 2+1
quantum gravity, respectively, is proposed. A complex time dependent
Schr\"odinger equation (generalized Wheeler-DeWitt equation) for the wave
function of the universe exists in the spontaneously broken symmetry phase at
Planck energy and in the early universe, uniting quantum mechanics and general
relativity. An explanation of the second law of thermodynamics and the
spontaneous creation of matter in the early universe can be obtained in the
symmetry broken phase of gravity.Comment: 10 pages, minor change and reference added. Typos corrected. To be
published in Class. Quant. Grav