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Universe's wall?

  1. Mar 13, 2005 #1
    If u reach the end of the universe, do u think there's a wall? All thing must have an end right?
     
  2. jcsd
  3. Mar 13, 2005 #2

    Chronos

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    Not at all. Even if the universe is finite, it wraps around on itself like a donut. Everywhere it always appears just the same as anywhere else.
     
  4. Mar 13, 2005 #3
    you can answer yourself, just imagine the following situation:

    Suppose you are at what u were calling "the edge of the Universe"
    isn't there anything beyond?
     
  5. Mar 13, 2005 #4
    You are assuming the universe is finite and flat. This is what some early humans may have thought when considering the flat earth :

    If u reach the end of the earth, do u think there's a wall? All thing must have an end right? (it's another version of Chronos' answer)
     
  6. Mar 13, 2005 #5
    Even if there was a wall, what did U think was it made up of.

    In a way I believe there is a wall, its made of space. It goes farther as you try to touch it. but I also believe that it is going farther at speed of light as the first light from the big bang must be still going farther.

    Chronos
    {
    But if universe is as U say it is then we should be able to see echos of big bang, shouldnt we ?
    }
    This is my view only , please dont delete it.
     
  7. Mar 13, 2005 #6

    Garth

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    That depends on how large the circumference was.
    Looking for "echos of big bang", actually 'circles in the sky', is one way of constraining cosmological theory that is an active area of research.


    Garth
     
  8. Mar 13, 2005 #7
    One way to think of it is as one of those old mario games, or pacman, when you get to the side, and go through, you just end up on the other side....
     
  9. Mar 13, 2005 #8
    actually is believed that the Universe is flat, that is has a curvature k=0, but it doesn't constraint the topology to one possibility, a flat universe can have different topologies (infinite, an hypertorus,...) A topology of an hypertorus means that the universe is finite, but this doesn't mean that the universe has a "wall" indicating its ending. Similarly, if the universe is not flat (there are two other possibilities: that is spherical or that is hyperbolic), each of these two possibilities admits more than one topology
     
  10. Mar 13, 2005 #9
    past the edge is the
    NOT YET

    but as the edge is moving at light speed or faster with inflatesion/expansion

    BUT YOU CAN'T GET THERE FROM HERE

    so why worry :biggrin:
     
  11. Mar 13, 2005 #10

    Chronos

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    I won't delete it, I can't, and I would not if I could. My interest is in asking you to think again. Let's talk about the evidence and what it might mean.
     
  12. Mar 14, 2005 #11

    Phobos

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    Good analogy. People may envision an end of the Earth (like how ancient sailors were afraid of sailing off the end of the Earth) when they put themselves at the center (the beginning point). But those ancient sailors were not at the beginning point of the Earth's surface...they were just at some point on the surface. Like that, the universe has no beginning or end in ordinary 3D space. It may curve back on itself like a globe or it may be infinite in extent. We must be careful not to apply the geocentric view to our place in the universe.
     
  13. Mar 14, 2005 #12
    The analogy still needs one more refinement to address intuition that a manifold need be embedded in higher dimensional space. And unfortunately I can't think of a way to do that without resorting to Flatland examples.
     
  14. Mar 15, 2005 #13
    Ok , but U did not mention any observable evidence in this CASE ? did I miss something ?

    What do U wana me 2 thinkbout ?
     
  15. Mar 15, 2005 #14
    I had this dream a while ago where I was zooming thru the univerise and reached its end. The wall was solid and black and I touched it with my hand. :cool:

    Isn't the earth's ground the "end" of the earth?
     
    Last edited: Mar 15, 2005
  16. Mar 17, 2005 #15
    There is something deceptively incorrect about a universe being finite or progressing incessently into the unknown. However, it is what we call home now that is the infinite* universe.

    The tangible universe is the reflection of our intellect. It will expand or contract according to our subconcious whims. it is whatever or wherever we believe it to be.

    The infinite universe is thought, the center of anyone's universe is their mind-expanding anywhere.
     
  17. Mar 17, 2005 #16

    Phobos

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    This is the "flatland" problem that Rev Prez mentioned.

    As an analogy, travelling the surface of the Earth falls short of visualizing curved space. This is because you need to limit your reality to just the 2D surface of the Earth (there is no up/down...no "ground"). But of course our common sense knows the Earth is 3D and we immediately visualize the 2D surface curving into 3D space.

    For curved 3D space, you may be tempted to visualize a 4th dimension of space that it curves into, but we know of no such dimension. (we do however, have the 4th dimension of time to work with)
     
  18. Mar 18, 2005 #17
    That's a very good question: They teach us that space and time began with the big bang (before that there was no space and time) and that space itself is expanding (the distance between the galaxies). If so, what is outside this space-time?

    This is how the universe evolved according to the standard big bang model:

    http://www.nasa.gov/images/content/56200main_dark_expansion-lg.jpg
     
    Last edited: Mar 18, 2005
  19. Mar 18, 2005 #18

    Chronos

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    There is no 'outside', at least not any possible to observe.
     
  20. Mar 23, 2005 #19
    The answer is simple... no, there is no wall.
    You will fall off the edge, and land upon the back of the great turtle whose strength supports the pillars upon which the cosmos is held in balance.
     
  21. Mar 23, 2005 #20

    Phobos

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    Funny, but probably not helpful for david90. :smile:
     
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