Is There a Unified Theory Between General Relativity and Electromagnetism?

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Discussion Overview

The discussion centers around the question of whether there exists a unified and consistent theory that integrates general relativity with electromagnetism. Participants explore theoretical frameworks, historical attempts, and specific models related to this inquiry.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about a unified theory and requests textbook recommendations.
  • Another participant asserts that no successful unified theory exists, noting historical attempts, including those by Einstein.
  • A participant mentions that classical electromagnetism can be incorporated into general relativity by adding electromagnetic field terms to the action, citing Dirac's work and discussing charged black holes.
  • It is noted that while Maxwell's equations can be expressed in tensor form in curved spacetime, this does not equate to a unified field theory where gravity and electromagnetism are unified aspects of a single field.
  • A reference to Kaluza-Klein theory is made, highlighting its approach of using a five-dimensional framework to relate gravity and electromagnetism through a compactified dimension, while also mentioning the challenge of moduli stabilization in this context.

Areas of Agreement / Disagreement

Participants express differing views on the existence of a unified theory. While some acknowledge the integration of classical electromagnetism into general relativity, others emphasize that this does not constitute a true unification of the two fields. The discussion remains unresolved regarding the existence of a comprehensive unified theory.

Contextual Notes

The discussion highlights the distinction between incorporating electromagnetism into general relativity and achieving a unified field theory. There are also references to technical challenges associated with higher-dimensional theories.

Karimselim1997
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I want know is there any unified and consistent theory between general relativity and electromagnetism ? If yes could you provide me any textbook ? I'm interest
 
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Karimselim1997 said:
is there any unified and consistent theory between general relativity and electromagnetism ?

No. There have been various attempts at one over the years (Einstein worked on this for much of the latter part of his life), but none of them have worked out.
 
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Not quantum but classical electromagnetism is well considered in general relativity. Here I have text of Dirac. He says just add terms of electromagnetic field and charge-field interaction to action of the system. For an example we can treat charged black holes in GR.
 
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anuttarasammyak said:
classical electromagnetism is well considered in general relativity

In the sense that you can write the Maxwell Equations in tensor form in a curved spacetime and find consistent solutions to them, yes. But that's not the same as a unified field theory in which both gravity and electromagnetism are aspects of the same field. I understood the OP to be asking about the latter, but he's welcome to clarify.
 
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Zee's nutshell book on GR has a nice discussion on Kaluza-Klein theory, 5-dim GR with one dimension curled up into a circle. The extra freedom allows you to write the 5-dim. metric as a 4-dim. metric plus one 4-dim. vector potential A and a scalar.

However, making a dimension compact is 1 thing; keeping it compact is another. This problem is known as moduli stabilization, and is also a technical subtlety in string theory.

That's the closest answer I can think of.
 
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