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 [wikipedia.org] 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-
;)
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