The Quantum Gravity and Unified Theories Division
In the 1970s, physicists had already managed to unite three of the four fundamental forces of nature into one theory – the standard model of particle physics. Only gravity is still firmly resisting integration. Although the inherent contradictions between quantum theory and general relativity become apparent only in the unbelievably small dimensions of the Planck scale (10-33 cm), they must be resolved if we want to understand what "happens" inside a black hole or at the Big Bang.
Thus gravitational physicists today are searching for a new theory of quantum gravity to unite general relativity and quantum field theory, solving the mathematical contradictions in the process. The main approaches to quantum gravity (canonical quantisation, supergravity and string theory, as well as non-pertubative schemes), are all represented at the Albert Einstein Institute in Potsdam, with special emphasis on novel ansätze that may overcome difficulties with the existing approaches.
The sought-after theory of quantum gravity is likely to revolutionize our current concepts of space and time at extremely small distances in radical ways. In particular, the familiar distinction between spacetime and matter may well turn out to be invalid at the Planck scale.