We explore gravity and its manifestations from the largest to the smallest scales in the Universe. At the largest scales, we investigate how gravity determines the history of our Universe as a whole, and the evolution of structures within it. At intermediate scales, we explore the properties of black-hole populations, the interactions of a black hole with its environment as well as the generation of gravitational waves and black-hole shadows. At the smallest scales, we study the quantum properties of gravity and spacetime.
We investigate how cosmological observations can constrain gravity as well as the global properties of the Universe. We strive to differentiate the necessary from the arbitrary properties of cosmic structures. We devise tests for specific aspects of gravity, for isolating subtle details and differences to predictions of general relativity, and we refine statistical methods for this and related purposes. We scrutinize modified theories of gravity beyond general relativity and how such theories may resolve open questions and remaining problems of general relativity and cosmology. We address the recent cosmic evolution visible at low redshift as well as cosmic inflation in the early Universe.
Luca Amendola, Matthias Bartelmann, Arthur Hebecker,
Lavinia Heisenberg, Annalisa Pillepich (MPIA), Björn Malte Schäfer
We study black holes across the entire range from solar-mass black holes to supermassive black holes. We contribute to several international collaborations which probe black-hole physics (the Einstein Telescope collaboration and the LIGO-Virgo-KAGRA collaborations through gravitational waves, the Event Horizon Telescope through black-hole images and galaxy surveys/JWST-observations for supermassive black holes, Gaia data for dormant black holes).
We also explore how black holes affect the larger-scale environments they are embedded in, such as star clusters as well as entire galaxies. We also investigate the spacetime structure of black holes beyond General Relativity and observational imprints of modifications of General Relativity.
We develop and explore the mathematical foundations, theoretical formulation and phenomenological implications of quantum gravity. In this endeavor, we focus on string theory, asymptotically safe gravity, tensor models as well as causal set quantum gravity. We develop each of these approaches further and investigate connections between them, aiming for the fundamental physical principles. We connect to mathematics on one side, and to particle physics, cosmology and black-hole physics on the other in order to develop the phenomenology of quantum gravity.
Astrid Eichhorn, Razvan Gurau, Arthur Hebecker, Jan Pawlowski, Johannes Walcher
The interplay of quantum fields with a curved spacetime background can be simulated in the laboratory. We use a Bose-Einstein condensate to simulate cosmological spacetimes and test the predictions of quantum field theory on curved backgrounds.
