Fractal Structures Driven by Self-gravity: Molecular Clouds and the Universe

In the interstellar medium, as well as in the Universe, large density fluctuations are observed, that obey power-law density distributions and correlation functions. These structures are hierarchical, chaotic, turbulent, but are also self-organizing. The apparent disorder is not random noise, but can be described by a fractal, with a deterministic fractal dimension. We present a new theory of the self-gravity thermodynamics, that could explain the existence of these fractal structures, and predict their fractal dimension. The media obeying scaling laws can be considered critical, as in second order phase transitions for instance. This revised version was published online in July 2006 with corrections to the Cover Date.