Models and Applications of Loop Quantum Gravity

In order to explore the implications of proposed theories of quantum gravity for space and time, it is often useful to study the theories' effects for special space-times. Symmetric solutions and related models present one of the main examples of this approach, motivated by the wish to extract physical information from (classical or) quantum gravity. While proposed quantum gravity theories are sufficiently complex that how to construct symmetric models is not obvious, several techniques have been developed for one of the current candidates for a quantum theory of gravity, loop quantum gravity. For realistic situations, which are never exactly symmetric, more general constructions containing at least small deviations from symmetry such as spatial inhomogeneities will be developed. This generalization may allow calculation of quantum gravity effects which might be relevant to cosmological observations or to understand properties of black holes.

Since quantum theories of gravity are still being developed, any information on the behavior of possible candidates, in particular in physical scenarios, will help to guide the theoretical construction. Quantum gravity, in turn, is widely believed to be essential for the understanding of the universe at a fundamental level. This applies in particular to the two main areas of application of application of the simplified, cosmology and black holes, which also receive wide interest in the general public. Models as developed by this project enable intuitive explanations which make such a broad dissemination possible. In simplifying the complex full theories, suitable models also provide ideal entry points for students or researchers new to the field.