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Doughnut-shaped Universe: Astronomers say Universe is small and finite

  1. May 27, 2008 #1


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    Ulm University scientists have found evidence suggesting that the Universe is small and finite, and shaped like a 3-torus (doughnut).

    They used three techniques to compare predictions of how the cosmic microwave background's temperature fluctuations in different areas of the sky should match up in both an infinite Universe and a doughnut one. In each case, the doughnut gave the best match to the Wilkinson Microwave Anisotropy Probe data.

    The team has even been able to pinpoint the probable size of the Universe: 56 billion light years across.

  2. jcsd
  3. May 27, 2008 #2


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    Thanks for spotting this SF!

    The article in Nature is free, if anyone wants to read it

    It is a news article written for general audience about a research paper that was posted last year on arxiv.

    Do we Live in a "Small Universe"?
    Ralf Aurich, Holger S. Janzer, Sven Lustig, Frank Steiner
    (Submitted on 10 Aug 2007 (v1), last revised 8 Apr 2008 (this version, v2))

    "We compute the effects of a compact flat universe on the angular correlation function, the angular power spectrum, the circles-in-the-sky signature, and the covariance matrix of the spherical harmonics coefficients of the cosmic microwave background radiation using the full Boltzmann physics. Our analysis shows that the Wilkinson Microwave Anisotropy Probe (WMAP) three-year data are well compatible with the possibility that we live in a flat 3-torus with volume ~5x10^3 Gpc^3."

    Notice that they don't claim to have proved it. They say that the 3-year WMAP data are COMPATIBLE with it being torus.
    If they check it against the 5-year WMAP data they could well get a negative. More data may be able to rule out what they say.

    Glen Starkman is something of an expert---has done a study of this very question that came up with negative finding. He says wait till we have data from the Planck satellite. It will provide a much more detailed map of the CMB. then we will see if the torus of that volume is still a possibility.

    About the numbers, their model is a cube with a volume 5000 cubic gigaparsecs
    (and then identify the opposite faces of the cube so going out one side makes you reappear coming in the other side.)

    so we have to take the cube root of 5000, and that will tell the length of the side of the cube
    Last edited: May 27, 2008
  4. May 27, 2008 #3


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    Two articles by Glenn Starkman et al which did NOT find evidence of torus topology are

    1. arXiv:astro-ph/0604616 [ps, pdf, other]
    Title: Extending the WMAP Bound on the Size of the Universe
    Authors: Joey Shapiro Key, Neil J. Cornish, David N. Spergel, Glenn D. Starkman
    Comments: 9 pages, 16 figures
    Subjects: Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc)
    2. arXiv:astro-ph/0310233 [ps, pdf, other]
    Title: Constraining the Topology of the Universe
    Authors: Neil J. Cornish, David N. Spergel, Glenn D. Starkman, Eiichiro Komatsu
    Comments: Submitted to PRL
    Journal-ref: Phys.Rev.Lett. 92 (2004) 201302

    BTW if you take the cube root of the volume that paper gives you get that the SIDE OF THE CUBE has length 1709 Megaparsecs. Which is the same as 56 billion light years.
    So I guess that is where the number 56 billion came from. It is the cube root of the volume that they give
  5. May 27, 2008 #4
    I'm sorry, I had to:

    Homer Simpson would be very proud!

    Other than that, this is very interesting stuff, even to a non-donut-fanatic such as myself.

    Good find, both of you!
  6. Dec 19, 2008 #5
    That is very intresting , but i have read that the universe is flat. They carried out some experiment where they launched two beams from earth and always addded up to 180 degrees a right trangle. Earth is the location of 90 degrees on a triangle
  7. Dec 19, 2008 #6
    You mean no matter the two beams shot at whatever direction?
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