Quantum Gravity in de Sitter Space
June 20, 2011
Abstract: Our universe appears to have undergone a phase of exponential inflation at early times, and may currently be entering a second inflationary phase. However, we still do not know how to make sense of quantum gravity in an inflating universe. Even basic conceptual questions, such as the nature of observables and the origin and interpretation of the entropy of a cosmological horizon, remain unresolved. We describe recent progress on quantum gravity in the simplest inflating spacetime — de Sitter space. Remarkably, under some circumstances the partition function of quantum Einstein gravity can be computed exactly. This allows us to make precise the notion of the ‘wave function of the universe’ for certain simple theories of quantum gravity.