Classical Unified Field Theory

[Schreiberdk]

Hi there PF.

I have recently been working on the Classical Unified Field Theory, and i want to ask, why the Einstein-Maxwell equations does not candidate for a Classical Unified Field Theory, since it incorporates both general relativity and electromagnetism, into a single formalism?

I have seen that people, after the discovery of general relativity, have pursued the dream of a unified field theory, in this case in the classical sense. So why ain't this the truth about the Einstein-Maxwell equation?

Also, when this is not true for the EME, could one do unification, in the same way used to discover the Grand Unified Theory in the 1970s, by using groups symmetries at very high temperatures?

\Schreiber

 

[zhermes]

The Einstein-Maxwell equations are only applicable to finding the metric from electromagnetic energy explicitly (e.g. Maxwell's EM energy tensor, instead of the stress energy tensor). And thus does not include EM effects. Further, even if E&M and gravity were fully united in such a way, it still wouldn't include the strong or the weak forces.

The very idea of a CUFT is strange, as it would clearly be incomplete... and thus largely superfluous.

 

[Schreiberdk]

Yes, know it would be incomplete and an highly odd theory, but rather, it could help us understand the final unified field theory, as a classical limit to it. So in my understanding, it would be to some help to finding "The unified field theory" :)

 

[zhermes]

That's excellent reasoning. Personally, I don't think its possible: our ability to unify EM with the weak interaction, and later with the strong is fundamentally quantum. I don't think there's any reason to believe that it could be done (informatively) classically. But hey, it would be pretty cool if it could be!

 

[Schreiberdk]

Now my question is, how does on derive the coupling constants for the electromagnetic field and theory of general relativity. Does these coupling constants come from gauge symmetries of the theories?