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  1. #1
    fcathell@msn.com's Avatar
    fcathell@msn.com Guest

    Default Basic Astronomy Question 101



    Another example of rampant scientific illiteracy!

    FC


  2. #2
    Stevie B's Avatar
    Stevie B Guest

    Default Basic Astronomy Question 101


    Don't knock dumkoff atheistic nutjobs until you've tried one. I
    understand that they can be quite rewarding, especially if the dumkoff
    atheist takes out her dentures first.

    Let's hear it for the big bang theory! Yay!


  3. #3
    MitchAlsup@aol.com's Avatar
    MitchAlsup@aol.com Guest

    Default Basic Astronomy Question 101


    Anonymous wrote:

    Lookup the resupts from the COBE and WMAP data. These 'telescopes'
    measured the background glow from the big bang and fit it to the Big
    Bang model of the universe including 'inflation'. The data confirms the
    Big Bang theory and sets limits to the size, shape, geometry, and age
    of the universe. The data indicates that the universe if 12.7 BYO +/-
    0.2 BY.


    The age of the universe and the size of the universe are not that
    closely related. The size of the universe is on the order of 90 B light
    years and much of it is beyond our horizon.


    No, the universe is isotropic (to a high degree of precision) and the
    earth is no closer to the center than anything else! The universe is so
    large (and still expanding) that everything we can see with large
    telescopes can all be considered the center of the universe with equal
    presision.


  4. #4
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default Basic Astronomy Question 101

    On 27 Sep 2005 07:41:38 -0700, MitchAlsup@aol.com wrote:


    I'm not sure how you meant this, but to avoid confusion: the reason that
    any point (or really, no point) can be considered the center of the
    Universe has nothing to do with its size. It is a consequence of the
    fact that an object with more than three dimensions (the Universe) has
    no center that can be represented by a three-dimensional point.

    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com

  5. #5
    Brian Tung's Avatar
    Brian Tung Guest

    Default Basic Astronomy Question 101

    This is getting a bit away from Basic Astronomy 101.

    Chris L Peterson wrote:

    There's no such thing as a three-dimensional point. And even
    interpreted as "a point in three dimensions," it's still unclear.
    I *think* you mean that any space that is curved into more than three
    dimensions cannot have a center within that space (not that it can't
    have a center in three dimensions). Technically, that's not always
    true, but for the usual 3-manifolds under discussion, I think it is.

    By analogy, there are 2-manifolds that contain their centers--centers
    both in the sense of an expansion fixed point, and in the sense of
    geometric center. However, the 2-sphere (curved into three dimensions)
    is not one of them, and that's the sort of shape we usually mean in
    these discussions.

    In ordinary English, a sphere is like a flat surface curved into three
    dimensions, and although it has a center, that center lies nowhere on
    the surface itself. That means that all points *on the surface* can
    equally well (or equally poorly, depending on your point of view) be
    considered as the center of that surface.

    --
    Brian Tung <brian@isi.edu>
    The Astronomy Corner at http://astro.isi.edu/
    Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
    The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
    My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

  6. #6
    Rob Johnson's Avatar
    Rob Johnson Guest

    Default Basic Astronomy Question 101

    In article <kaoij1pnev0cd6e81qjvrd7ta87gm2ruhp@4ax.com>,
    Chris L Peterson <clp@alumni.caltech.edu> wrote:

    The observable universe has only three observable physical dimensions.
    However, since the physically observable universe is embedded in a
    higher dimension, the observable matter in the universe may not have
    a center inside of itself. Depending on the embedding, the universe
    may have a center in the higher dimension.

    Here is a two-dimensional analog. Consider an ant on an inflating
    balloon with grape juice spilled on it. The ant crawls around in any
    direction and finds pools of grape juice contracting under surface
    tension yet each pool is moving away from the others because of the
    inflation of the balloon. No pool of grape juice could be considered
    the center of the grape juice universe.

    If the ant were to follow the inflation of the balloon back to when it
    was extremely small, it would find the center of the balloon in space-
    time was the time when the inflation of the balloon began. However,
    since all the surface of the balloon at that time was essentially in
    one place, the ant would not be able to specify the center on the
    surface of the balloon.

    If we extrapolate the ant's two physical dimension universe to our
    three physical dimension universe, the center of the universe is at
    the time of the Big Bang, but at every spatial point since all the
    spatial points were at the same place.

    Rob Johnson <rob@trash.whim.org>
    take out the trash before replying

  7. #7
    Starlord's Avatar
    Starlord Guest

    Default Basic Astronomy Question 101

    If no cat has 8 tails, but every cat has one more tail than no cat, then all
    cats have 9 tails.

    And that is just about as clear as anything else.


    --

    The Lone Sidewalk Astronomer of Rosamond
    Telescope Buyers FAQ
    http://home.inreach.com/starlord
    Astronomy Net Online Gift Shop
    http://www.cafepress.com/astronomy_net



    "Rob Johnson" <rob@trash.whim.org> wrote in message
    news:20050927.092537@whim.org...



  8. #8
    Brian Tung's Avatar
    Brian Tung Guest

    Default Basic Astronomy Question 101

    Rob Johnson wrote:

    Just a minor quibble.

    Although it is most natural for us humans to think of the universe
    as being embedded in a higher space, there is no need for that to be
    the case. The universe can exhibit the metric characteristics of
    being curved without possessing the *geometric* characteristics of
    being curved.

    In other words, it is possible for GR to predict the behavior of the
    fabric of space-time, including all of its space and time warping
    effects, without the universe being physically curved into a further
    dimension. There's no easy visual analogy for this; the very term
    "curvature" practically denies one. But one can go through the
    mathematics just the same.

    Current TOEs mention large numbers of "extra" dimensions with finite
    and small extent. It is worth noting that they are supported in large
    part by symmetry arguments, which are convincing from an elegance
    perspective but hardly ironclad. I'm not sure whether they speak
    directly to embedding.

    --
    Brian Tung <brian@isi.edu>
    The Astronomy Corner at http://astro.isi.edu/
    Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
    The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
    My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

  9. #9
    Rob Johnson's Avatar
    Rob Johnson Guest

    Default Basic Astronomy Question 101

    In article <dhbuom$d2n$1@zot.isi.edu>,
    brian@isi.edu (Brian Tung) wrote:

    True, Gauss's Theorema Egregium says that irrespective of embedding,
    the curvature of a surface can be determined purely from the intrinsic
    metric <http://mathworld.wolfram.com/GausssTheoremaEgregium.html>.

    However, in order to speak of a center to the universe, I made the
    probably unsupportable assumption that our space-time is embedded in a
    higher dimension, mainly to show that even if we are embedded, there
    might be no point currently that could be considered the center of the
    universe.

    Rob Johnson <rob@trash.whim.org>
    take out the trash before replying

  10. #10
    donstockbauer@hotmail.com's Avatar
    donstockbauer@hotmail.com Guest

    Default Basic Astronomy Question 101

    If no cat has 8 tails, but every cat has one more tail than no cat,
    then all cats have 9 tails.

    And that is just about as clear as anything else.

    ***************************

    Isn't polysemy wonderful?


 

 
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