222
R. Barrett and P. P. Delsanto
11.4 The Foamy Distribution of Galaxies
As we have seen earlier in our discussion of Olber’s Paradox, the prevailing
view of the universe in the nineteenth century was a uniform distribution of
stars throughout space. Subsequently it became clear that stars are grouped
in galaxies, and it was presumed that these galaxies were homogeneously
distributed. However, we now know that the galaxies are distributed in clusters and these clusters in superclusters. Looking at the broadest picture we
still expect the superclusters to be spread homogeneously. In this belief, we are
again applying Occam’s Razor, for a homogeneous distribution is one without
structure, which involves fewer assumptions than one with structure.
However, the evidence from observation is not in accord with this view.
In Fig. 11.2 we have a slice of the sky, centred on the earth, taken from
the Sloan Digital Sky Survey. This survey has created extremely detailed
Fig. 11.2 Distribution of galaxies in a slice of sky, centred on the earth. The picture is
taken from the Sloan Digital Sky Survey. Image courtesy of M. Blanton and the Sloan
Digital Sky Survey (https://classic.sdss.org/includes/sideimages/sdss_pie2.jpg (accessed
2020/6/18))
R. Barrett and P. P. Delsanto
11.4 The Foamy Distribution of Galaxies
As we have seen earlier in our discussion of Olber’s Paradox, the prevailing
view of the universe in the nineteenth century was a uniform distribution of
stars throughout space. Subsequently it became clear that stars are grouped
in galaxies, and it was presumed that these galaxies were homogeneously
distributed. However, we now know that the galaxies are distributed in clusters and these clusters in superclusters. Looking at the broadest picture we
still expect the superclusters to be spread homogeneously. In this belief, we are
again applying Occam’s Razor, for a homogeneous distribution is one without
structure, which involves fewer assumptions than one with structure.
However, the evidence from observation is not in accord with this view.
In Fig. 11.2 we have a slice of the sky, centred on the earth, taken from
the Sloan Digital Sky Survey. This survey has created extremely detailed
Fig. 11.2 Distribution of galaxies in a slice of sky, centred on the earth. The picture is
taken from the Sloan Digital Sky Survey. Image courtesy of M. Blanton and the Sloan
Digital Sky Survey (https://classic.sdss.org/includes/sideimages/sdss_pie2.jpg (accessed
2020/6/18))