Is A Wrap-Around Universe Acceptable To Mainstream Cosmology?

[common_sense_seeker]

It isn't a new idea, but one which seems little debated in the mathematically led modern day cosmology. There is a new book on the subject The Wraparound Universe (http://www.akpeters.com/product.asp?ProdCode=3090) and here's a piece by Neil Turok The Cyclic Universe (http://www.edge.org/3rd_culture/turok07/turok07_index.html). Is it okay to talk about these strange ideas?

[D H]

Yes. Discuss away. I can't say much right now; today's going to be a busy day for me.

[common_sense_seeker]

I haven't read the book, but wouldn't gravity waves/particles which travel around the universe then become a force of repulsion i.e. still a force of attraction but in the opposite direction? Could this not be a major factor in the comological expansion that we observe?

[D H]

Whoa there! You haven't even read the book and you are already making conjectures based on your interpretation of it? Don't do that, please.

Here are three lay articles at Physics World on the first subject. I'll quote from the last one only, which is a review and critique of the book cited in the OP.

Is the universe a dodecahedron? Physics World, Oct 8, 2003 (http://physicsworld.com/cws/article/news/18368)

A cosmic hall of mirrors, Physics World, Sept 26, 2005 (http://physicsworld.com/cws/article/print/23009)

Not wrapped up yet, Physics World, Feb 2, 2009 (http://physicsworld.com/cws/article/print/37535)
Alas, a more detailed look at the relevant data obtained using NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) shows that the conclusion seems unwarranted. Among other groups, I, along with my colleagues Anastasia Niarchou and Levon Pogosian, concluded that the “power spectrum” data used in Luminet’s original work does not statistically warrant any explanation beyond the plain-vanilla standard cosmological model: a simply connected, spatially flat universe. Examining the detailed patterns of CMB fluctuations as Niarchou and I have done more recently — with a method that uses all available information — shows that Luminet’s preferred model is actually very strongly disfavoured.

Moreover, Luminet’s explanation ignores a crucial a priori weakness of his proposal: it requires the universe to have a very slightly curved geometry. This, in turn, requires the radius of the hyper-spherical universe (the curvature scale) to be comparable to the so-called Hubble distance (the distance a beam of light could have travelled since the Big Bang). Why should these numbers be nearly equal?


In fact, an interesting topology, especially paired with a curved geometry, is neither required nor particularly supported by the data. In contrast, one of the crucial features of cosmic inflation — the fact that inflation flattens the geometry of the universe so that the curvature scale becomes immeasurably large — is supported by the vast majority of cosmological data, and therefore by cosmologists (lightly mocked as the “inflation lobby” by Luminet). Nonetheless, the paired questions of the correctness of inflation and of the topology of the universe are by no means closed. We await further data, especially from European Space Agency’s Planck Satellite, which is due to be launched in April.

[common_sense_seeker]

Thanks for the informative answer D H. I'll try and get the book first before commenting any further on the subject.

[common_sense_seeker]

Moreover, Luminet’s explanation ignores a crucial a priori weakness of his proposal: it requires the universe to have a very slightly curved geometry. This, in turn, requires the radius of the hyper-spherical universe (the curvature scale) to be comparable to the so-called Hubble distance (the distance a beam of light could have travelled since the Big Bang). Why should these numbers be nearly equalThis is something I intend to look into. It doesn't seem too outlandish or unsolvable to me.
We await further data, especially from European Space Agency’s Planck Satellite, which is due to be launched in April.[/indent]Successfully launched on 14 May 2009. The results should be interesting ESA Planck Satellite in depth (http://sci.esa.int/science-e/www/area/index.cfm?fareaid=17)

[common_sense_seeker]

Thanks for the informative answer D H. I'll try and get the book first before commenting any further on the subject.I've now read the book, which I highly recommend. There's currently no direct evidence of a wraparound universe, although the idea isn't new; it was a popular notion familiar to Einstein and his contemporaries.

[Cyperium]

It isn't a new idea, but one which seems little debated in the mathematically led modern day cosmology. There is a new book on the subject The Wraparound Universe (http://www.akpeters.com/product.asp?ProdCode=3090) and here's a piece by Neil Turok The Cyclic Universe (http://www.edge.org/3rd_culture/turok07/turok07_index.html). Is it okay to talk about these strange ideas?Of course it is okay to talk about these strange ideas! Don't let the world get to you!

However, there is little evidence that the universe wrap around as it seems rather flat.

[common_sense_seeker]

Of course it is okay to talk about these strange ideas! Don't let the world get to you!

However, there is little evidence that the universe wrap around as it seems rather flat.It only needs to be slightly off flat to be wraparound though. Could be a really big universe..

[Cyperium]

It only needs to be slightly off flat to be wraparound though. Could be a really big universe..Yes, could be.

Or it could wrap around in another dimension? Where all we see as straight is actually curved?


Well, if the Big Bang happened and spacetime was created with it, then obviously it must be some kind of wrap-around. But I don't think we know enough to assume what is obvious in this case.