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I Cosmic void

  1. Dec 17, 2016 #1
    Hey guys,

    Regarding the cosmic void between galaxies, is it really empty? If you read articles from pop science sources mostly said "cosmic voids are devoid of matter", "there are full of dark matter", etc.

  2. jcsd
  3. Dec 17, 2016 #2


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    Well, "empty" gets to be a bit more complicated than you might think, as witnessed by the many hundreds of threads on this forum discussing just that.

    Basically it is "empty" by human standards but not really. First and foremost there is a huge amount of radiation passing through it plus neutrinos and the odd dust particle here and there.

    EDIT: also, NEVER take pop-science seriously.
  4. Dec 17, 2016 #3


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    Cosmic voids are not completely empty, they just contain a much lower density of matter and dark matter than other areas of the universe (such as around galaxy clusters).
  5. Dec 17, 2016 #4
    Well I am just going to be happy I don't care. :-).

    But seriously while we are on this topic, strictly in technical term, the void doesn't mean cosmic dust, radiation, or dark matter or anything like that. There are supposed to be this Higgs field and who knows what else that we have not discovered. I mean how does gravity wave travel? If indeed gravity waves have been detected, this empty space at least will have some type of gravity field or whatever that is.
  6. Dec 17, 2016 #5


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    Void in this context simply means that the density of matter and dark matter across a very wide area of space is much lower than average. Remember, context matters! :wink:
  7. Dec 19, 2016 #6
    What about the space being created all the time between galaxies. Does that space have any atoms in it?
  8. Dec 19, 2016 #7


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    Space is not being "created". The distance between unbound objects is simply increasing over time. (that's a subtle but important distinction)
    Also, no, expansion does not create new matter.
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