Hierarchical organization is a frequently occurring phenomena in natural processes. It is a tradition in the natural sciences to use this fact, at least implicitly, when constructing models. We refer to an approximate description of the system, typically valid on a specific length- and time-scale. In physics it is a tradition to divide the different research fields by the physical scale where they apply, e.g., elementary particle physics, nuclear physics, mesoscopic physics, physics of condensed matter, and astronomy. Similar domain boundaries, also based on separation of physical scales, exist in biology. A coarse grained hierarchy may be expressed e.g., as molecules, organelles, cells, tissues, organs, organisms, ecosystems [1].