Planck Mission and M-Theory Cosmology

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Discussion Overview

The discussion revolves around the implications of the Planck Mission's observations of the Cosmic Microwave Background (CMB) for M-theory cosmology and inflationary models. Participants explore the potential for these observations to support or challenge existing theories, particularly focusing on the detection of non-Gaussianity in the CMB and its relevance to different inflationary models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants recall that the Planck Mission's observations could provide support for M-theory cosmology while potentially weakening support for inflationary models, particularly through the detection of non-Gaussianity.
  • Others express uncertainty about how the Planck Mission would test M-theory, noting that non-Gaussianity is a significant focus of research.
  • One participant references the Planck Blue Book, indicating that it discusses brane inflation and how the CMB may be affected differently than in standard inflationary models.
  • It is suggested that while Planck's findings may not "prove" M-theory cosmology, they could provide some supportive evidence.
  • Another participant mentions that Planck is expected to narrow the model space regarding CMB temperature anisotropies and provide measurements of E-mode and possibly B-mode polarization.
  • One contribution highlights that detecting non-Gaussianities could distinguish brane/string inspired models of inflation from others, with specific predictions for equilateral and local non-Gaussianities.
  • There is a note that string/brane inspired inflation models may struggle to generate large B-modes, and a detection of such signals would pose challenges for these models.

Areas of Agreement / Disagreement

Participants express a mix of uncertainty and differing views on the implications of Planck's findings for M-theory and inflationary models. There is no consensus on how the observations will impact these theories, and multiple competing perspectives remain present.

Contextual Notes

Participants acknowledge limitations in their understanding of the Planck Mission's findings and the complexity of the models discussed, including the dependence on definitions and unresolved aspects of the theories.

dm4b
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A ways back, I seem to remember reading on the Planck Mission page that it's observations of the CMB could help foster support for M-theory cosmology and weaken support for Inflation, or vice-versa.

I thought it had something to do with detection of Non-Gaussianity in the CMB.

I could not find what I was looking for on the Planck page again.

Am I remembering this at all correctly and, if so, does anybody know what Planck found?

Thanks!
dm4b
 
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dm4b said:
A ways back, I seem to remember reading on the Planck Mission page that it's observations of the CMB could help foster support for M-theory cosmology and weaken support for Inflation, or vice-versa.

I thought it had something to do with detection of Non-Gaussianity in the CMB.

I could not find what I was looking for on the Planck page again.
I'm not exactly sure what you're referring to. I am unaware of any way in which Planck will test M-theory, but non-Gaussianity is one thing that people are looking very hard for.

dm4b said:
Am I remembering this at all correctly and, if so, does anybody know what Planck found?
The Planck CMB results are currently scheduled to be released in a little under two years. Basically, understanding the systematic and statistical errors is a lot of work.
 
Chalnoth,

I wasn't sure what I was referring to either ;-)

But, I remembered that I did read about some of this in the Planck Blue Book:

http://www.rssd.esa.int/SA/PLANCK/docs/Bluebook-ESA-SCI(2005)1_V2.pdf

On Page 55, they start to discuss brane inflation. I haven't had time to read all of it yet, but they do appear to mention how the CMB can be effected differently than from regular inflationary models.

In the end, I don't think anything they find is supposed to actually "prove" M-Theory cosmoslogy and brane inflation - just provide some support.
 
dm4b said:
Chalnoth,

I wasn't sure what I was referring to either ;-)

But, I remembered that I did read about some of this in the Planck Blue Book:

http://www.rssd.esa.int/SA/PLANCK/docs/Bluebook-ESA-SCI(2005)1_V2.pdf

On Page 55, they start to discuss brane inflation. I haven't had time to read all of it yet, but they do appear to mention how the CMB can be effected differently than from regular inflationary models.

In the end, I don't think anything they find is supposed to actually "prove" M-Theory cosmoslogy and brane inflation - just provide some support.
Right. Planck is likely to narrow the model space somewhat. It should basically be the final word on CMB temperature anisotropies, it should provide an unprecedented measurement of the E-mode polarization, and it may, if we are very lucky, provide the first measurement of B-mode polarization (by lucky I mean that the nature of the universe would have to be just right to produce enough B-mode polarization for Planck to be able to see it).
 
Thanks Chalnoth!

Boy, another two years! Seems like I am waiting in anticipation for too many exciting results - LHC and the Higgs, LIGO and Gravitational waves, Planck and the CMB ..

Wish these guys would hurry up! :)
 
And to add to Chalnoth's list of important finds, it will detect the presence of non-Gaussianities (NGs). It is perhaps this observable that most sharply distinguishes brane/string inspired models of inflation from others. Dirac-Borne-Infeld (DBI) inflation is a brane inflation model that predicts large amounts of a special kind of NG, so-called 'equilateral' NG, typically with a magnitude [itex]f^{\rm equil}_{NL} \sim \mathcal{O}(10) - \mathcal{O}(100)[/itex]. Planck is expected to have a sensitivity of [itex]f^{\rm equil}_{NL} \sim 20[/itex] or so. NGs are also vital for distinguishing between single and multifield inflation models, like the curvaton. Here the NGs are of a distinctly different form, called 'local' NGs. Planck will do a better job of seeing these -- [itex]f_{NL}^{\rm local} \sim 5[/itex]. These are not exclusively related to string inspired models, but local NGs would tell us that all is not right with the canonical single field inflation paradigm.

Also, it's interesting to note that most string/brane inspired inflation models have a difficult time generating large B-modes (gravitational waves). A detection of a large B-mode signal in the CMB would be difficult for string/brane inflation to wiggle out of, although, as with any theory that is suitably vaguely defined, there are ways.
 

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