String/ M theory and Dark Matter

[SammyB]

Hello, I am currently doing a research project on alternative theories to dark matter. I have covered all the main candidates fairly well such as nonsymmetrical gravity, conformal gravity and MOND etc. But I would really like to include a section on how string theory or M theory could explain the Dark Matter problem. The problem is that I seem to be unable to find any papers or reputible sources on this subject, I guess it is a very vauge and unexplored area at the moment, but I was wondering if anyone new of any good links or books.

Also is it true that M-theory is no longer thought of as the 'unifying' string theory and is considered to just be another version of string theory?

Is it true that gravitons are closed strings and that only closed strings can propagate through higher dimensions? If so why?

As you can probably tell I'm not very schooled at all in String Theory...I'm still an Undergraduate!

Thanks in advance

 

[Chalnoth]

Hello, I am currently doing a research project on alternative theories to dark matter. I have covered all the main candidates fairly well such as nonsymmetrical gravity, conformal gravity and MOND etc. But I would really like to include a section on how string theory or M theory could explain the Dark Matter problem. The problem is that I seem to be unable to find any papers or reputible sources on this subject, I guess it is a very vauge and unexplored area at the moment, but I was wondering if anyone new of any good links or books.

Most solutions that make use of ideas from string theory don't attempt to provide an alternative for dark matter, but instead attempt to explain how the theory could produce a particle that could explain dark matter. I think you'd be hard pressed to find anything other than this.

Also is it true that M-theory is no longer thought of as the 'unifying' string theory and is considered to just be another version of string theory?

I believe it's considered that M theory and string theory are one and the same thing, but we just didn't realize that until recently.

Is it true that gravitons are closed strings and that only closed strings can propagate through higher dimensions? If so why?

If string theory is accurate, then the graviton is a state of a string. If this is correct, then a necessary conclusion is that the universe has extra dimensions. One possible way in which the extra dimensions might exist but without our ability to detect them (yet) would be if we were confined to a three-dimensional surface in this higher-dimensional space. Basically, due to the properties of the graviton state of a string, they cannot be confined to such a surface, and so necessarily spread out into the full space. Other strings that make up the normal matter around us, on the other hand, can be confined.