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B What is the center of the universe?

  1. Jul 2, 2015 #1
    I read in a book that there is no center of the universe because for example, you put dots around a balloon, and when you put air into the ballon, the dots will seperate from each other, and each dot will see themselves as the center of the balloon, depending on the dots' perspective. That only applies if our universe is spherical, like a balloon. But the accepted shape of our universe is flat, in that case, what is the center of our universe? Please tell me if i miss out something, and i am open to any other theories/facts. Thank you and have a nice day!:)
     
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  3. Jul 2, 2015 #2

    Drakkith

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    There is no center of the universe that we know of.
     
  4. Jul 3, 2015 #3
    There is no definitive center of the Universe. The only center we can define is the center of the observable Universe but the Universe itself extends far beyond that. Exactly how far can't be determined.
     
  5. Jul 3, 2015 #4

    Chronos

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    The 'center' of the universe is an observer dependent illusion, just like the 'edge' of the universe. Wherever you may be in the universe it appears you are both at its 'center' and at its most ancient point. See any logical disconnects with that?
     
  6. Jul 3, 2015 #5

    phinds

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    You would do well to read the link in my signature
     
  7. Jul 4, 2015 #6
    The balloon thing is meant to be a 3-d model of 4-d space. In other words, the inhabitants of the balloon universe are trapped in the thin skin of the balloon. If they go in any direction, they end up back where they started, hence, no center that they can detect. Extrapolate to the real universe...
     
  8. Jul 4, 2015 #7

    phinds

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    No, it is essentially a 2D model of 3D space. We don't live in 4D space. I suggest that you too read the link in my signature.
     
  9. Jul 8, 2015 #8

    SteamKing

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    Everybody knows it's Boston, Massachusetts. After all, Boston is nicknamed "The Hub", as in "the Hub of the Universe". :wink:

    https://en.wikipedia.org/wiki/Boston_nicknames
     
  10. Jul 8, 2015 #9
    How would you define the center? If you are on a line, the center would be defined as the point where you have the exact same amount of distance in front of you and behind you. If both ends go off to infinity, no matter at what point in the line you are, you always have infinity in front and behind you, therefore you can not define a location where you have the same distance in front and behind you. infinity does not equal itself.
     
  11. Jul 8, 2015 #10
    Thanks for the reply guys! I did some research and i understand it now :)
     
  12. Jul 8, 2015 #11
    You don't have to be rude, i asked because i didn't understand :)
     
  13. Jul 8, 2015 #12

    phinds

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    I agree. Just so you know, if you object to a post, you can report it using the report button that exists in each post. The moderators have a low tolerance for rude behavior, as I know very well 'cause I get called on the carpet every now and then when I forget to bite my tongue :smile:

    EDIT: sometimes people come here and ask very basic questions, clearly without having made the slightest attempt to figure things out for themselves. This can be annoying, but you clearly did not do that (and even if you had, the moderators still ban rudeness).
     
  14. Jul 9, 2015 #13

    Chronos

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    Phinds, don't be put off by naive questions - we all have suffered that disorder. Cosmology is complicated. I like them, they are the easiest to answer with any sense of confidence.
     
  15. Jul 9, 2015 #14

    phinds

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    Oh, I have NO problem with naive questions. I was full of them when I first decided a few years back to start learning a bit about cosmology and quantum mechanics. What I object to is people who make no effort on their own. The OP had clearly made an attempt to figure it out and was understandably puzzled, which is the perfect time to come here to PF for help.
     
  16. Jul 10, 2015 #15
    Not exactly accepted theory, but I tend to think of the center of the universe as the past and the universe expands into the future. Works well in a 4D model, even better in a 5D model of Hugh Everett's many worlds interpretation so long as the universe is not flat.
     
  17. Jul 10, 2015 #16

    Drakkith

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    Unfortunately this is likely to cause even more confusion than the standard analogies.
     
  18. Jul 29, 2015 #17

    DHF

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    I had similar questions on the Center of the universe a while back. I found it difficult to grasp the concept of no center but then someone here (I am sorry I cant remember who posted) asked "where is the center of the surface of the Earth?" That helped me get my head around the idea that there is no center to the universe.
     
  19. Jul 30, 2015 #18
    OK, perhaps you could share your understanding since your beginner perspective would help someone like me. Others here may join in, of course.

    I have this image of a starting point expanding outwards in the form of the ballooning surface. At that moment a center ceases to exist and becomes a surface with the matter of the original center on it, each bit of that matter expanding away from each other as the surface of the balloon expands.

    If that's not a reasonable image, albeit simplistic, by what description can the universe be said to have had a starting point from which matter originated?

    Further, does this mean that, in the balloon model, that the balloon is empty and all that exists is on the surface?

    Further again, I may be having a problem with this idea that a void, an emptiness, now exists within this balloon upon which the surface rests, and a void into which the surface is expanding. I guess this goes to the perhaps mistaken idea that something existed outside the origin into which things are expanding.

    By the way, if there's a beginner's forum I should use, please let me know.
     
    Last edited: Jul 30, 2015
  20. Jul 30, 2015 #19

    Drakkith

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    It can't be said to have a starting point at all. That's the entire point (pun not intended).
     
  21. Jul 30, 2015 #20

    Bandersnatch

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    @nuwanda it's easier to start from the present time and go backwards, rather than the other way around.
    Working some more with the analogy at hand, if you have this balloon's surface, and start deflating the balloon, then the surface will become more and more compact, and points on it closer and closer together, but no matter how small you'll make the balloon, it'll never stop having a surface and will not turn into a point.
    Even an infinitely small balloon is still a balloon.
     
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