On the distribution of galaxies and galaxy clusters

The fact that galaxy and galaxy clusters distributions exhibit fractal properties is well established since twenty years^1,2. Nowadays, the controversy concerns the range of the fractal regime, the value of the fractal dimension and the eventual presence of a cross-over to homogeneity^3,4,5. In this paper we briefly review the methods of analysis based on the concepts of modern statistical physics which are suitable to characterize intrinsical irregular structures. Then we summarize the main results.