From: scerir (scerir@libero.it)
Date: Sat Jul 29 2000 - 11:55:43 MDT
Scerir wrote:
But the recent statistical analysis of the experimental data already shows
also that the distribution of galaxies is fractal up to the deepest observed
scales.
Robin Hanson wrote:
Odd you should mention this now, as a lot of press has been given lately
to the Two-Degree Field survey finally that structure is no longer fractal
above about 300 Million light years.
Prof. L. Pietronero wrote that one of the most extraordinary findindings of
the last two decades in observational cosmology has been the existence of a
network of voids and structures in the distribution of galaxies in space.
The enormous scales of these structures were completely unsuspected in
earlier extensive observations of galaxy distributions, in which only
angular coordinates were measured, obscuring the richness subsequently
revealed in the third coordinate. These findindings have become increasingly
difficult to reconcile with standard cosmological theories, in which the
approach to homogeneity at large scales is a central element.
Observationally, however, not only the scale at which the matter
distribution approaches an average density, but the very existence of such a
scale, remains the subject of intense debate.
At small scales it is well established that the distribution of galaxies is
fractal, and the debate can be phrased in terms of the deviation from this
behaviour towards homogeneity. Some consensus has been achieved about the
optimal statistical methods to use in the analysis of three dimensional
data.
Independently of the data, however, resistance to the fractal picture is
certainly to a considerable degree due to the conviction that it is
incompatible with the framework of the standard theories and in particular
with the high degree of isotropy of the microwave background radiation.
In this respect one should note that in standard models the origin of
radiation and baryonic matter is separate, with the latter
being created in a process completely distinct from the origin of the
primordial radiation bath.
The isotropy of the latter is therefore not fundamentally tied to the
distribution of the matter, and the only real constraint is how much any
such distribution actually perturbs the radiation.
May I also ask: is cosmology a science?
http://www.newscientist.com/ns/19990821/fracturedu.html
http://pil.phys.uniroma1.it/debate.html
http://xxx.lanl.gov/abs/astro-ph/0002124
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