2005/05/12 by Saswat Sarangi, Sarangi, Saswat, S. -H. Henry Tye +1 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th) #gr-qc #hep-th
paper · pdf · doi:10.48550/arxiv.hep-th/0505104
39 pages, 8 figures. Added comments, discussion, references, one new figure
arxiv created 2005/06/01 · arxiv updated 2009/12/01
When the semi-positive cosmological constant is dynamical, the naive Euclidean Einstein action is unbounded from below and the Hartle-Hawking wavefunction of the universe is not normalizable. With the inclusion of back-reaction (a crucial point), the presence of the metric perturbative modes (as well as matter fields) as the environment (that is, to be integrated or traced out) introduces a correction term that provides a bound to the Euclidean action. So the improved wavefunction is normalizable. That is, decoherence plays an essential role in the consistency of quantum gravity. In the spontaneous creation of the universe, this improved wavefunction allows one to compare the tunneling probabilities from absolute nothing (i.e., not even classical spacetime) to various vacua (with different large spatial dimensions and different low energy spectra) in the stringy cosmic landscape.