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Why is the universe shaped like a pebble?

  1. Jul 5, 2010 #1
  2. jcsd
  3. Jul 5, 2010 #2
    That diagram doesn't represent the apparent shape of the Universe. Imagine an Atlas of the Earth, In order to represent all geographical anomalies, such being the continents and oceans, it is impossible to display it 2-dimensionally when the Earth is 3-dimensional. Similar to this Atlas: http://skywalker.cochise.edu/wellerr/students/pleistocene-extinction/extinct_files/image008.jpg
    The photo is essentially a mapping of the 3-dimensional Cosmic Microwave Background but stretched onto a 2-dimensional surface which shows it's curvature, you can try to attach the ends of the mapping and you'll create a sphere. There is no conclusive shape of the Universe but since we are surveying the sky from a single location and light sources emitted come from every direction converge at the specific point (Earth) the Universe appears to be spherical

    Last edited: Jul 5, 2010
  4. Jul 5, 2010 #3
    So what is that white line in the middle like an equator?

    Why does it appear to have red polar caps?

    Universal warming perhaps?
  5. Jul 5, 2010 #4
    No in fact the telescope (Planck telescope) used to measure the Cosmic Microwave Background Radiation measures precisely (supposedly) the excess radiation from the Big Bang. When the Universe went through a process of rapid expansion (inflation) it cooled enough for stable atoms to form - the left over photons that weren't absorbed have been propagating through space and have been transformed to Microwaves because of Universal Expansion. The temperature of the Cosmic Microwave Background is 2.725 K which puts it in the Microwave Range of 160.2 GHz. What I stated before is this isn't the Universe. This is radiation that is found in the Universe which originated during the Big Bang. To imagine the Universe to be spherical is rather naive because there is no experimental description of the Universe's Shape : http://en.wikipedia.org/wiki/Shape_of_the_Universe
    The irregularity in the Cosmic Microwave Background: Poles and equator, is due to anisotropies or variances which is dependent on the size of the observed region. Experimental and theoretical research correlate this effect to thermal variations caused by quantum fluctuations of matter in a very tiny space (the early universe). Therefore during the Big Bang when radiation was more prominent than matter and the Universe was extraordinarily small there were quantum fluctuations that occurred and when the Universe cooled these dynamics are visualized in the apparent non-uniform display in the Cosmic Microwave Background.

    - Kevin
    Last edited: Jul 5, 2010
  6. Jul 5, 2010 #5


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    Staff: Mentor

    From the article, that's the Milky Way Galaxy:
    Um....are you serious?

    Did you read any of the article? Please read all of it.
  7. Jul 5, 2010 #6
    You're absolutely correct, I didn't read the article it just seemed to look like the the Milky Way but I was convinced otherwise. But the object being described isn't really in accordance with his question - which I already answered. It's just the way it is being projected, it's similar to putting the Geography of the Earth on a 2-dimensional surface as I stated above.
  8. Jul 7, 2010 #7
    Thanks for posting the article, Alice :)
    ^^This is cool!
    And I cannot believe this :
  9. Jul 19, 2010 #8
    The Universe, in fact, is flat :).
  10. Jul 19, 2010 #9
    Current research and experimental testing states tangentially that the Universe is flat. The immediate paradox is that our observations are greatly limited. The Universe way possibly be a manifold of negative or positive curvature yet our ocular limitations only allow us to percieve the Euclidean Space which is observed at small distances which is our Observable Universe. The question is still unanswered, physics is based off observation and if a flat universe is what we discover than that's what will be said as of today.
  11. Jul 20, 2010 #10


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    Science Advisor
    Gold Member

    The pebble shape is due to flat map projection - same as that used to portray a map of the earth in 2D.
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