Extremely exciting matter: for physicists, extreme conditions are high temperatures and densities such as those found in the first millionth of a second after the Big Bang - some trillions of degrees Celsius (hundred thousand times hotter than the interior of the Sun) and several times the density of matter in atomic nuclei (many hundreds of millions of tons per cubic centimeter).

Under these conditions, matter is dominated by the so-called strong interaction. This is one of the four fundamental forces of Nature. For example, it is responsible for the structure of atomic nuclei consisting of protons and neutrons and for the internal structure of the latter consisting of quarks and gluons. Under extreme conditions, strong-interaction matter develops new forms of state, comparable to the different phases of water such as ice, liquid, and vapour. While this is being examined experimentally at large particle accelerators such as the LHC at CERN in Geneva and, in the near future, at the international particle accelerator facility FAIR in Darmstadt, the Collaborative Research Centre/TransRegio 211 is examining the topic from a theoretical point of view.

The fundamental properties of strong-interaction matter are examined in 14 subprojects and applied to the physics of the early Universe and of heavy-ion experiments. The unique feature of the new CRC-TR is the combination of complex numerical simulations on high-performance supercomputers ("lattice QCD") with analytical methods. Physicists at the universities Bielefeld, Darmstadt, and Frankfurt participate in the Collaborative Research Centre.