Planck Mission and M-Theory Cosmology

[dm4b]

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

 

[Chalnoth]

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.

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.

 

[dm4b]

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.

 

[Chalnoth]

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).

 

[dm4b]

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! :)

 

[bapowell]

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 f^{\rm equil}_{NL} \sim \mathcal{O}(10) - \mathcal{O}(100). Planck is expected to have a sensitivity of f^{\rm equil}_{NL} \sim 20 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 -- f_{NL}^{\rm local} \sim 5. 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.