Calling All Cosmologists

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Mythbuster, Mar 27, 2006.

  1. Mythbuster Mushroomed Registered Senior Member

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    I heard someone mention the other day that because the Universe is isotropic and homogenous, that it shows that we're the center of the universe.

    I tried doing some preliminary reading on this, but most of what I find includes math that is beyond my understanding. What I did find is that the universe being isotropic or homogenous is assumed for other cosmological theories.

    Has anyone else ever heard this? What are your takes on isotropy or homogeneity?
     
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  3. Mosheh Thezion Registered Senior Member

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    you know what happens... when people make assumptions.

    science... theory... is full of assumptions... hence the controversy.

    -MT
     
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  5. mathman Valued Senior Member

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    "I heard someone mention the other day that because the Universe is isotropic and homogenous, that it shows that we're the center of the universe."

    All observational evidence seems to agree with the isotropic and homgeneous part. The second part (center) is nonsense. Any point in the universe (as far as we know) has the same property - therefore every point is the center?????????????
     
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  7. Novacane Registered Senior Member

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    Good. Just exactly where at which point in the universe was the 'Big Bang' supposedly centered at? Science wants to know.

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  8. Tortise Registered Senior Member

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    I knew the universe revolved around me! Wow wouldn't that be naive. What are the odds? Impossible to nothing?

    That question may not have much meaning if our current thinking is correct. It may be like asking where did a balloon start expanding.
     
    Last edited: Mar 28, 2006
  9. superluminal . Registered Senior Member

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    Oy.

    The entire universe has, as far as anyone knows, always existed. Evidence points to the fact that about 14 billion years ago it was in a state such that the metric that describes volume today was much smaller. So small in fact that the entire VISIBLE universe (called our Hubble volume) was the diameter of an atomic nucleus. Very dense, very hot. One day, the metric began to expand at an enormous rate, allowing the universe to cool and matter to "condense" out of the sea of energy. This was the "Bang" everyone talks about.

    Yet there were, and are (most likely), an infinte number of these volumes which make up the universe. We only see as far as we do because anything farther is receeding so fast that the light is red-shifted to undetectable wavelengths (our Hubble Horizon). We appear to be at the center because everything everywhere is receeding equally from everything else.

    An in habitant on a planet 10 billion light years from here would see exactly what we see. A visible universe about 14 bly in diameter, uniform and homogeneous in all directions. Same goes for an observer a trillion or a gazillion light years from here. The universe is infinite in extent, with an infinite number of Hubble volumes - one for every dimensionless point in the infinite universe.
     
  10. Mosheh Thezion Registered Senior Member

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    THATS alot of statements....

    do you believe all of it?

    do you have any doubts at all?? on any point?

    -MT
     
  11. Poincare's Stepchild Inside a Klein bottle. Registered Senior Member

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    Where is the center of the universe?

    The answer depends on how you look at it...either every point...or at no point.

    (I am not kidding.)
     
  12. aguy2 Registered Senior Member

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    Mythbuster,

    I think I can make a good case showing that the visible universe does not represent either a homogenitic structure or an isometric exspansion. I would contend that the visible universe is acting as if it were a pulse/jet of an ideal liquid that has transited from a laminar (even) to a turbulent state due to lose of momentum.
    aguy2
     
  13. Poincare's Stepchild Inside a Klein bottle. Registered Senior Member

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    Here is another question for you...

    Is the universe finite and without boundary?

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  14. RoyLennigan Registered Senior Member

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    don't get too hasty in your conclusions, everything is an assumption, not just science. science is actually probably the least controversial subject out there.
     
  15. Lucas Registered Senior Member

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    Indeed, the vast consensus is that the Universe has an infinite volume (concordance model). But the data does not preclude the possibility of a Universe with finite volume, and i prefer the idea of the universe having finite volume, though an Universe having a finite volume does not necessarily have a center
     
  16. Mosheh Thezion Registered Senior Member

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    THE FACT THAT YOU SAY THIS... shows... you dont know much about cosmology.

    physics.. chemistry.. electronics... are pretty well defined.

    cosmology is very argueable....

    -MT
     
  17. aguy2 Registered Senior Member

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    Superluminal says, "A visible universe about 14bly in diameter, uniform, and homogeneous in all directions."
    aguy2 says:
    1) Seeing as we can't seem to see the future, wouldn't the visible universe be 14bly in radius not diameter?
    2) Uniformity: although the early visible universe seems to have acted as if it were an ideal liquid in a laminar or even flow, the more current universe is acting as if it is quite turbulent.
    3) Homogenity: 3rd year Wmap observations, among other things, seem to indicate that the visible universe has been non-homogeneous from at least the inflationary epoch, estimated to be about 13.7 billion years in our past.
    aguy2
     
  18. superluminal . Registered Senior Member

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    Nitpicker.

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  19. superluminal . Registered Senior Member

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    Sure. Plenty. Why?
     
  20. superluminal . Registered Senior Member

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    A universe with finite volume demands that it be IN some other volume or context. Yes?
     
  21. Pete It's not rocket surgery Moderator

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    I don't think so, super. It might, but...
     
  22. superluminal . Registered Senior Member

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    I dunno. I have a hard time imagining anything with a finite volume not having an outside.
     
  23. Pete It's not rocket surgery Moderator

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    I have a hard time imagining something that travels like a wave and interacts like a particle... but that doesn't mean that the universe demands that no such thing exists, right?
     

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