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Australian Study Backs Major Assumption of Cosmology
cylonlover writes "In mankind's attempts to gain some understanding of this marvelous place in which we live, we have slowly come to accept some principles to help guide our search. One such principle is that the Universe, on a large enough scale, is homogeneous, meaning that one part looks pretty much like another. Recent studies by a group of Australian researchers have established that, on sizes greater than about 250 million light years (Mly), the Universe is indeed statistically homogeneous, thereby reinforcing this cosmological principle."
Most comments seem to be vying for most funny, but if you do happen to care about visualizing the scale, the distance to our closest full-sized galactic neighbor, the Andromeda Galaxy is 2.5 Mly. That is 1% of the homogeneity scale cited by the article. So, they are saying that things seem smooth averaged over scales merely 100 times bigger than the distance to the nearest extra-galactic clump which is sized comparably to The Milky Way. That's actually pretty smooth, in context.
For scale:
Milky way diameter ~ 0.11 Mly,
Local Group (Milky way, Andromeda, etc...) diameter ~ 10 Mly,
Virgo Supercluster diameter ~ 100 Mly.
The existence of superclusters is part of why local homogeneity is not observed. However, the claim is only that any given region of about 250 Mly is on average about the same as any other region of the same size. So, even if that homogeneity holds true as you reduce scale (i.e. look for an average Earth) there's still a huge difference in thinking that you've got AC posters on alt-Earth asking about their alt-Australian universe homogeneity study. Besides, the frequency of Earth like planets should be signnificantly higher within our own statistically homogeneous region, but we still haven't had cookies dropped off from our older-to-the-hood neighbors. Check out the Fermi Paradox for fun reading.
Actually - there's some discussion to having been visited in prehistory and early history earth, but that's a subject for an alt. and not an alt-
;)
Until the Billion light-year across VOID is explained, this article makes no sense! http://www.newscientist.com/article/dn12546-biggest-void-in-space-is-1-billion-light-years-across.html
It's still an assumption. If the universe is infinite, then this observation says nothing about the non-observable universe. Any statements about the non-observable portions are purely assumptions.