The aim of the meeting is the extend and foster the exchange between people working from theoretical and experimental side on the prediction and detection of modified and quantum gravity.

Further information can be found below and at

https://www.we-heraeus-stiftung.de/index.php?id=1536

Two major unsolved questions in fundamental physics are related to the gravity: What is the nature of Dark Matter and Dark Energy, and, what is the theory of quantum gravity? From the theoretical point of view these questions stimulated various fundamental approaches to a theory of quantum gravity, such as string theory, loop quantum gravity, canonical quantum gravity, noncommutative geometry, asymptotic safety and others as well as phenomenological models such as doubly or deformed special relativity and the relative locality framework. Moreover, numerous classical modifications of General Relativity have been suggested such as scalar-tensor theories, f(R)-theories, bi-metric gravity, tensor-vector-scalar gravity or metric affine gravity, Poincare gauge theory, telleparallel gravity, Finsler gravity and many more.

The viability of these alternative or extended theories of gravity has to be tested by comparison of predictions with experimental data. It is important that this comparison is done on all scales from the whole universe, i.e. on cosmological scales, via galaxy-clusters, galaxies, binary systems, black holes, the solar system, satellite experiments, down to laboratory experiments at micrometer and smallest scales, i.e. high energy scales looking for new elementary particles like axions or WIMPs.

This seminar aims for discussing predictions and their comparison with experiments of extended and modified classical and quantum theories of gravity, on all scales. The goal is to identify theories, which are consistent on all scales, and, to identify observables, in which deviations of general relativity or the quantum nature of gravity is most likely to manifest itself.

**Organizing Committee**

Christian Pfeifer, Univeristy of Tartu, Estonia

Claus Laemmerzahl, University of Bremen, Germany