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TrickyDicky
#63
Sep15-10, 01:39 PM
P: 3,036
Quote Quote by Chalnoth View Post
Correct, but the point remains that it's a special position within the observable universe. That is enough, I think.
Right, it is a special location inside the observable universe since in a truly inhomogenous universe, observers on the edge of the observable universe of the original observer would probably loose the isotropy(unless isotropy lies in the eye of the observer, like beauty :) and is intrinsic to relativistic observers no matter what).
I am not sure if that is really enoug, though, as the cosmological principle is applied to the whole universe, not only to the observable part.

Quote Quote by Chalnoth View Post
Well, I don't think most cosmologists think that homogeneity is likely to be more correct on extremely large scales. That is, in order for a region to become nearly homogeneous, it really needs to have some time to reach some sort of thermal equilibrium. But once your distances get large enough, there won't have been any chance for such widely-separated regions to reach thermal equilibrium, and so you expect wildly different sorts of behavior.

Of course, given current observations, we expect this distance to be much larger than the size of our observable universe, but I think we expect things to get less homogeneous eventually as you go beyond our observable region.
I tend to agree with you, but if I were to speculate about what cosmologists opine on this subject I'd say they pretty much don't think about it and when they do they favor homogeneity from a certain scale all the way to the extreme.
But the more I think of it the more convinced I am that homogeneity cannot be empirically confirmed, only suspected.