Physics tries to measure the quantifiable natural phenomena by means of targeted experiments and to describe them theoretically using the simplest possible basic models. In constant cross-fertilization of experiment and theory, physics today has penetrated into the areas of the largest dimensions - in astrophysics - as well as those of the smallest dimensions - in elementary particle physics. In the research so successful integration of theory and experiment already in training to anchor, it is one of the guiding principles of physics studies at the Technical University of Dortmund.