# All - Defining

1. Dec 13, 2009

### Qwe$t Hi! This is my first post. I have a question of cosmological importance - literally and figuratively. The Standard Model is the most accepted theory of (almost) everything, yet is unable to make sense of gravity. String Theory can explain it all theoretically through quantitative analysis, but is lacking substantive empirical testing. Plasma Cosmology has many answers for the quandaries that most cosmologists face, yet suffers the same fate as the other two theories, to some degree. Here are my questions. Is it a consensus opinion among the brightest physicists/cosmologists that these ideas are, and must be exclusive? Would it be possible to integrate the three on some level? Forgive me if my questions sound naive or even ignorant, but I'm a biologist with a fascination for, but limited understanding of, such lofty ideas! Thanks ahead of time. 2. Dec 14, 2009 ### tom.stoer I agree. I do not agree with the quantitative analysis. String theory is not able to uniquely derive low-energy physics. There is a huge number of different "vacua" corresponding to different interactions, forces, symmetries and particle content. Some of these solutions are rather similar to our universe, but none of them is identical. It is an open question whether this non-uniqueness is a major flaw of the theory or if it's simply a fact that theories allow for different low energy solutions (just as in ordinary low-energy physics where different solutions are allowed: different atoms and molecules; different phases like gas, liquid, solid for the same material; different crystal structures, ...) What do you mean by "plasma physics". A plasma is a special state of matter relevant to astrophysics (stars, interstellar plasma), but it is certainly not a fundamental theory but just "ordinary physics". You can observe a plasma in every neon tube. String theory tries to derive the standard model or (due to its non-uniqueness) a class of models similar to the standard model as low energy effective theory. So the standard model should emergy as a special solution of string theory as seen in the limit of low energies. This should include gravity as well. However there are several open issues, e.g. uniqueness, how to get rid of supersymmetry, testable predictions, .... Not all jobs physicists agree that string theory is the unique "theory of everything". Many are quite concerned as it is still not able to make testable predictions. The standard model should emerg as a low energy effective theory; plasma physics is a special topic within the standard model. Tom 3. Dec 14, 2009 ### Qwe$t

Thank you, Tom.

I think I do have the gist of the different theories. I appreciate you delineating some salient features of String Theory. As for my use of the word "quantitative", I meant it as a reference to the numerous equations which have been put forth by String Theorists in a attempt to validate their ideas mathematically. I did state that many of the permutations have not been subject to empirical testing.

I also realize that the "Standard Model" is used as a derivative for String Theory. My question concerns taking what we know and expounding on it by including other possible ideas such as "Plasma Cosmology."

When I use the term "Plasma Cosmology" I am referring to the ideas proposed by Hannes Alfvén, who won a Nobel Prize for them in the 60's. This theory tried to explain the universe's evolution via the interaction of plasma with electromagnetism. He is best known for the use of the term "ambiplasma" when referring to the universal make-up. This equivalent mixture of matter and antimatter and the resulting separation through annihilation reactions, supposedly yielding huge energy releases, was used by Alfvén to explain the universal state.

I don't know how accepted Alfvén's ideas are. I am just a layman wondering if anyone is attempting to create new amalgams of existing theories, beyond the more generally accepted ideas.

Thanks so much for the response. I hope this makes my use of "Plasma Cosmology" a little more understandable.

4. Dec 14, 2009

### tom.stoer

It is a rather well developed and broadly accepted theory; string theory tries to derive it from some more fiundamental concepts. Falsifying string theory does not necessarily imply falsifying the standard model.

I have to admit that I never heard about this theory before. I just started reading about it in Wikipedia http://en.wikipedia.org/wiki/Plasma_cosmology; [Broken] from what I see is is rejected by the majority of the physicists and cosmologists. I don't see how it could be combined with the mainstream approaches.

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