Dr. Manuel Krämer (IF USz)

Quantum cosmology and applications of the Wheeler-DeWitt equation

The unification of quantum theory and gravity is one of the most crucial open problems in physics. It is necessary to have a theory of quantum gravity in order to consistently describe Nature and to resolve singularities that are inherent in General Relativity. Several approaches to a theory of quantum gravity have been developed, but in order to ultimately decide which approach describes Nature best, we need testable predictions. A promising scenario to look for such effects is the highly energetic inflationary phase in the very early universe, which can be studied within the framework of quantum cosmology. Furthermore, quantum-cosmological models also serve as a mathematically simpler testbed to study conceptual questions of quantum gravity. In this talk, I will give an introduction to a rather conservative approach to quantum cosmology based on a canonical quantization that leads to the Wheeler-DeWitt equation. I will present how this approach has been applied to study whether quantum-gravitational corrections to the power spectra of inflationary perturbations can be observed in the Cosmic Microwave Background and whether singularities that appear in classical cosmology can be resolved.