This seminar is funded by the Wilhelm und Else Heraeus Stiftung. It is a private foundation, which supports research and education in science, especially in physics. Among German physicists the foundation is recognized as the most important private funding institution in their field. Part of the activities of the foundation is carried out in close cooperation with the German Physical Society. The Wilhelm und Else Heraeus Stiftung regularly offers seminars to a limited number of participants from universities, research institutes and industry. The topics of the meetings cover the whole range of research in physics and its neighboring disciplines. Emphasis is put on lively discussion.