If we take the need for a nonperturbative theory of quantum gravity seriously, we must address the question of how our available tools can realistically get us there and what kind of results we may therefore be able to derive. Lattice gravity based on Causal Dynamical Triangulations (CDT) provides a blueprint in terms of both methodology and results. Analogous to lattice QCD, it is not so much an "approach" to quantum gravity as the best-developed way to construct and evaluate the gravitational path integral nonperturbatively. It has allowed us to move away from formal considerations in quantum gravity to extracting quantitative results on the spectra of invariant quantum observables, describing physics near the Planck scale. A breakthrough result of CDT quantum gravity in four dimensions is the emergence, from first principles, of a nontrivial, nonperturbative vacuum state which exhibits properties compatible with a de Sitter universe. I will summarize these findings and also discuss the new quantum Ricci curvature, which opens the door to constructing new observables that can relate to early-universe cosmology.
Teilnahme
Präsenz im Röntgen-Hörsaal und online.