Jean-Pierre Eckmann, Esa Jarvenpaa, Maarit Jarvenpaa, Itamar Procaccia
On the Fractal Dimension of the Visible Universe
(377K, postscript)

ABSTRACT.  Estimates of the fractal dimension $D$ of the set of galaxies in the 
universe, based on ever improving data sets, tend to settle on $D\approx 2$. 
This result raised a raging debate due to its glaring contradiction 
with astrophysical models that expect a homogeneous universe. A recent 
mathematical result indicates that there is no contradiction, since measurements of the dimension of the {\em visible} subset of galaxies is bounded from above by $D=2$ even if the true dimension is anything between $D=2$ and $D=3$. 
We demonstrate this result in the context of a simple fractal model, and 
explain how to proceed in order to find a better estimate of the true dimension of the set of galaxies.