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This recent paper is interesting:http://arxiv.org/abs/physics/0509171

It has some interesting images, and it offers some conceptual thinks.

It has some interesting images, and it offers some conceptual thinks.

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- Thread starter Spin_Network
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It has some interesting images, and it offers some conceptual thinks.

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JesseM

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http://www.arxiv.org/abs/astro-ph/0307282

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JesseM said:

http://www.arxiv.org/abs/astro-ph/0307282

There is a :N.B. that our results do not rule out the recently proposed dodecahedron model of Luminet, Weeks, Riazuelo, Lehoucq & Uzan, which has a 36 degree twist between matched circles.

If one looks closely in the link you provided?

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JesseM

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Ah, you're right. I found the link to that paper on this page, which seemed to say that Luminet and Tegmark had opposing conclusions:Spin_Network said:There is a :N.B. that our results do not rule out the recently proposed dodecahedron model of Luminet, Weeks, Riazuelo, Lehoucq & Uzan, which has a 36 degree twist between matched circles.

If one looks closely in the link you provided?

But I guess the person who wrote the page didn't notice that note, or that the N.B. was only added in a later draft.Astronomers have analyzed the WMAP data and they have obtained conflicting results. Jean-Pierre Luminet and his colleagues proposed that the data seemed to best fit a universe that was a spherical space formed by identifying opposite faces of a dodecahedron in a three-dimensional sphere [10]. You can build a dodecahedron, a polyhedron with 12 pentagonal faces, to see that the faces cannot be glued straight across without first using a twist. Other mathematicians and physicists, such as Max Tegmark and his colleagues, assert that the WMAP data in fact rules out a finite universe, and that measurements point to a flat Euclidean space which is infinite [11].

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JesseM

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Our results also rule out other models that predict

back-to-back matched circles. However, they do not rule

out the recently proposed dodecahedron model of [35]:

although this model predicts six pairs of diametrically

opposed circles of radius about 35°, the circles have a 36°

twist relative to their twin images, thereby eluding our

search method. After the original version of this paper

had been submitted, a more thorough analysis by Cornish

and collaborators [36] confirmed our findings and

improved them to rule out this and other twisted backto-

back models as well.

A maximally ambitious six-parameter “everything

bagel” circle search, corresponding to the general case

of arbitrary topologies, is currently being carried out

by Spergel and collaborators, and will be presented in

a forthcoming paper [37]. This should provide decisive

evidence either for or against the small universe hypothesis.

If this circle search confirms our finding that small

universes cannot explain the anomalies, we will be forced

to either dismiss the anomalies as a statistical fluke or to

search for explanations elsewhere, such as modified in-

flation models [21–26]. Even the fluke hypothesis might

ultimately be testable, since it may be possible to improve

the signal-to-noise of the large scale power spectrum

beyond the WMAP cosmic variance limit by employing

cluster polarization [38, 39] or weak gravitational

lensing [40] techniques.

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Garth

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There is a problem, not generally acknowledged, with the standard model interpretation of the WMAP/BALLOON/COBE data, that of the deficit of the low-l modes. While the standard model can explain this deficit as a statistical "fluke" as there are so few of these modes, the correlation between their positions and local geometry has led to their alignment being called "the axis of evil".

If this "AOE" is explained by local contamination of the data, or by a lensing of the cosmological dipole, then the deficit is made even worse.

Therefore these low-l modes (large angle anisotropies) may indeed be not consistent with the standard LCDM model prediction of a flat or open and therefore infinite universe but rather with a finite universe. Yet the data of l ~50 peak appears also consistent with a flat universe, so how can this be reconciled? By a model in which the universe is flat yet finite, such as the dodecahedron model, or by a*conformally* flat model.

Is this the reason WMAP2 is so long in being published?

Garth

If this "AOE" is explained by local contamination of the data, or by a lensing of the cosmological dipole, then the deficit is made even worse.

Therefore these low-l modes (large angle anisotropies) may indeed be not consistent with the standard LCDM model prediction of a flat or open and therefore infinite universe but rather with a finite universe. Yet the data of l ~50 peak appears also consistent with a flat universe, so how can this be reconciled? By a model in which the universe is flat yet finite, such as the dodecahedron model, or by a

Is this the reason WMAP2 is so long in being published?

Garth

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marcus

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In case it might be helpful in this thread, here is Niel Cornish homepage

http://www.physics.montana.edu/faculty/cornish/ [Broken]

and a sample article

http://arxiv.org/abs/astro-ph/0310233

"Constraining the topology of the universe"

I think he has considered the possibility that the U might have an unexpected topology, but (apologies) I'm a bit vague about this.

http://www.physics.montana.edu/faculty/cornish/ [Broken]

and a sample article

http://arxiv.org/abs/astro-ph/0310233

"Constraining the topology of the universe"

I think he has considered the possibility that the U might have an unexpected topology, but (apologies) I'm a bit vague about this.

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Chronos

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W Aurich et al. 2005 CMB anisotropy of the Poincaré dodecahedron

arXiv.org/abs/astro-ph/0412569

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