Welcome to the website of the

Gravitation and Relativity group

at the University of Cologne

We investigate Einstein’s theory of general relativity and its possible extensions in both the classical and the quantum regime. The methods involved include quantisation of general relativity, an analysis of its gauge structure, and quantum theory in curved backgrounds. Particular applications are cosmology and the physics of black holes.

Research projects

Quantum gravity and quantum cosmology
»  Canonical quantisation:
             ›  Quantum Geometrodynamics
             ›  Aspects of Loop Quantum Gravity
»  Semiclassical methods
»  Concept of time
»  Observational signatures
»  Singularity avoidance
Cosmology »  Inflationary universe
»  Interplay between particle physics and cosmology
»  Primordial fluctuations and structure formation
»  Quantum-gravitational effects
»  Decoherence in cosmological scenarios
Black holes »  Canonical quantisation
»  Interpretation of entropy
»  Primordial black holes
Foundations of quantum theory
»  Decoherence
»  Measurement process
Gauge aspects of gravity
»  Metric-affine gravity, world spinors
»  Poincaré gauge theory, Einstein–Cartan theory
»  Gravitational moments of the Dirac electron
»  Exact solutions, cosmological models
»  Two- and three-dimensional gravitational models
»  Physical and geometrical interpretation of nonmetricity and torsion
Classical electrodynamics
»  Axiomatic structure, coupling to gravity
»  Derivation of metric from electrodynamic structures
»  Violation of Lorentz invariance
Scientific computing
»  Computer algebra, Reduce with Excalc, Maple
Schwarzschild wormhole


Among the known interactions in Nature, gravitation is unique in that it acts universally on all kinds of matter and energy. It dominates on large scales (cosmology) and for compact objects (neutron stars, black holes), but is also important for everyday physics. The gravitational interaction plays a central role in the interplay between astrophysics, cosmology, and particle physics.

Modern gravitational theory started with Newton’s universal attraction law (1687): The gravitational force between two bodies is proportional to mass 1 times mass 2 divided by their distance squared. As soon as high velocities are involved between the masses, Newton’s theory is superseded by Einstein’s gravitational theory (1915), also called general relativity. Therein, gravitation is a manifestation of the geometry of four-dimensional spacetime. For macroscopic phenomena, general relativity is an experimentally well established theory.