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Is the universe truly expanding?

  1. Mar 24, 2015 #1
    Hello everyone, i am just bothered by the theory that our universe is expanding, if so i want to know, what substance is filling the void as our universe expands, and where does this substance come from,

    Thank you
     
  2. jcsd
  3. Mar 24, 2015 #2

    Doug Huffman

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    What is "the void" to which you refer, please?
     
  4. Mar 24, 2015 #3
    Space is expanding, but I don't know of any theory which infers that additional matter is being created as a result.
     
  5. Mar 24, 2015 #4
    For a thing to grow in size, expand ; something must be added into it... like a balloon. If you want a balloon to expand, u simply blow air into it. Dont you think the same thing should be happening if our universe is expanding?
     
  6. Mar 24, 2015 #5
    You could expand a balloon by placing it inside a contanier with less air density.
     
  7. Mar 24, 2015 #6
    okay, you do know that as something expqnd space is created, and has to be filled up by something, when i say void, i refer to this space wich has to eventually be replaced by something
     
  8. Mar 24, 2015 #7
    okay, now you do know that space is vaccume, can you get less pressure/ density than vaccume?.
     
  9. Mar 24, 2015 #8

    Doug Huffman

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    Cosmological space is mostly a hard vacuum with 10^-6 molecules per cubic centimeter, or, inverting, 10^6 cubic centimeters per molecule.
     
  10. Mar 24, 2015 #9
    ... i just wish you could answer my question, that is, what is getting filled into the space if it is growing
     
  11. Mar 24, 2015 #10
    Nothing additional has to be filling in the space, whatever atoms it already contains just get more spread out.
    Same thing as when you place your balloon in a low pressure container.
    You didn't need to put more air into the balloon, but it still got bigger.
     
    Last edited: Mar 24, 2015
  12. Mar 24, 2015 #11
    Okay, i assume you know about multiverse, there should be a boundry, that bounds everthing in our universe. If the universe is not expanding and its contants are being spread out, dont you think they would by now have spread outside of the universe?
     
  13. Mar 24, 2015 #12

    Doug Huffman

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    You are correct that there is a boundary between the universe and the hypothetical multiverse. That boundary is the limit of causation at lightspeed for the age of the universe. Practically, it is how far we can see, the universe's horizon.
     
  14. Mar 24, 2015 #13
    The multiverse is not known to be a fact, it's a possible explanation for some of the properties our universe has, but the existence of it has never been tested for,
    Some think it cannot ever be tested for, and therefore it isn't really a scientific proposition at all.
    However the expansion of the universe is a measurable fact.

    ... Must go now, I have visitors, I'm sure somebody else will like to assist wit your quesiton
     
  15. Mar 24, 2015 #14
    ARe you saying that this boundry is not fixed?
     
  16. Mar 24, 2015 #15
    T
    THanx
     
  17. Mar 24, 2015 #16
    I Think it is,logical to say that if realy the contants of the universe are moving apart and the universe is not expanding, then a few galaxies would be at that edge or outside
     
  18. Mar 24, 2015 #17

    Doug Huffman

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    Actually the large structures of the universe, galaxies and clusters and super clusters, are gravitationally bound together. It is the space between them that is expanding.
     
  19. Mar 24, 2015 #18
    If thats the case then, whats being injected into space inorder for it to expand, i mean it cant just expand and expand, some substance has to be added into it!
     
  20. Mar 24, 2015 #19

    Doug Huffman

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    What is space? Was there space before the Big Bang? Will there be space during the hypothetical Big Crunch?
     
  21. Mar 24, 2015 #20
    Space is vaccum, does this vaccum expand? Where does it come from? if we measure it to be 15 today, and tomorrow it is 20 where did the extra 5 come from???
     
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