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

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Discussion Overview

The discussion revolves around the concept of a doughnut-shaped universe, specifically the hypothesis that the universe is small, finite, and shaped like a 3-torus. Participants explore the implications of recent findings related to cosmic microwave background radiation and the topology of the universe, including comparisons between different models and interpretations of observational data.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants highlight findings from Ulm University suggesting that the universe matches predictions of a doughnut shape better than an infinite model, with a proposed size of 56 billion light years across.
  • Others reference a Nature article discussing the compatibility of WMAP data with a flat 3-torus model, emphasizing that the authors do not claim definitive proof but rather compatibility with the data.
  • A later reply mentions that further data from the Planck satellite could potentially challenge the toroidal model, as previous studies by Glenn Starkman and colleagues did not find evidence supporting torus topology.
  • Some participants express skepticism about the doughnut model, citing experiments that suggest the universe is flat, referencing observations where angles in triangles sum to 180 degrees when measured from Earth.

Areas of Agreement / Disagreement

Participants express a mix of viewpoints, with some supporting the doughnut-shaped universe hypothesis based on recent findings, while others argue for a flat universe based on different experimental results. The discussion remains unresolved, with no consensus reached on the universe's topology.

Contextual Notes

Participants note that the findings are based on specific observational data and models, and there are limitations regarding the assumptions made in the interpretations. The discussion also highlights the dependence on future data to clarify the universe's topology.

SF
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.

http://www.kurzweilai.net/news/frame.html?main=/news/news_single.html?id=8758
 
Space news on Phys.org
Thanks for spotting this SF!

The article in Nature is free, if anyone wants to read it
http://www.nature.com/news/2008/080523/full/news.2008.854.html

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

http://arxiv.org/abs/0708.1420
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:
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
 
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!
 
That is very interesting , 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
 
th3plan said:
That is very interesting , 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
You mean no matter the two beams shot at whatever direction?
 

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