Ever since man could think he has been curious to know about the physical world and why it is the way it is. Indeed, what he really wanted to know were the origin of and reasons for his existence but that is religion and not subject of this thesis. The curiosity about the physical world usually had very practical reasons - to know about the reasons and time of the seasons was good for a farmer, to know how to determine the true gold content of a crown good for a king. The increased knowledge about the physical world slowly led to demystification of nature and this is one of the big achievements of science: A clap of thunder did in fact not mean that a weather god was in a bad mood but simply that there was a sudden discharge of electrostatic charge built up between earth and a cloud. Since the discovery of more complex properties of nature mankind began to believe however, that eventually physicists would know the answer to everything and physics has become a replacement for religion for many - it has many of the properties of a religion, it has its own language, mathematics, it has priests who talk with each other in that strange language and who make predictions about the world which turn out to be true. Many non-scientists suffer from the illusion that it should therefore naturally also answer the very religious questions about the why and wherefor of the human existence. From a scientist's point of view, however, it is clear that all we really do is to describe the little bit of nature that is accessible to us, nothing more: We build telescopes to study the stars and the cosmos, we make statistical analyses of the behavior of children in problem families, and we build devices to study the physical world at very small distances. This brings us closer to the subject of this thesis.