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The 'Huge-LQG' quasar 'structure' does not violate homogeneity

  1. Jul 11, 2013 #1
    There was some excitement a few months ago about the discovery of the Huge-LQG quasar structure, claimed to be the "largest structure in the Universe", which was said to violate the cosmological principle and the assumption of homogeneity of the Universe. Some previous threads on this topic on this forum are here and here.

    Turns out this claim is wrong. A recently published paper (journal version here, free access version here) shows that the quasars actually support homogeneity as expected. A blog post explaining the issues at a less technical level is

    Quasars, homogeneity and Einstein

    A one-line summary would be "structures do not invalidate homogeneity; and the Huge-LQG is not really a structure anyway".
  2. jcsd
  3. Jul 11, 2013 #2
    Very interesting, thanks for the link
  4. Jul 11, 2013 #3
    thats good news thanks for posting that, lol I will have to adjust my thinking on when Homogenous is considered. I used to use the value 100 Mpc. I'll have to adjust to 130 Mpc.
  5. Jul 11, 2013 #4


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    It seems that cosmologists like to challenge their own assumption of uniformity. From time to time some observations are found that seem to indicate significant nonuniformity and we hear doubts about homogeneity and isotropy (the roughly even distribution of matter at large scale).
    Examples: "dark flow", Large Quasar Group (LQG), "Sloan Great Wall", "cold spot" or "great void".

    After a while the excitement about a particular challenge quiets down and whatever it is seems to be accepted as understandable as a fluke or statistical fluctuation within the context of overall large-scale average uniformity. I don't know much about this at a detailed level, only a vague impression of general consensus that the Cosmological Principle still seems acceptable.

    I wonder if there's a recent review article about this. Not just Large Quasar Group or any one specific challenge, but giving an overview.
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