Maxwell's equations and spacetime

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Discussion Overview

The discussion revolves around the differences between gravity and other forces in the context of General Relativity (GR) and the representation of Maxwell's equations. Participants explore the idea of using differential geometry to describe electromagnetic forces similarly to how gravity is represented in GR, while also addressing the historical attempts and theories related to this concept.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why gravity is fundamentally different from other forces in GR and references Einstein's attempts to find a geometric representation for Maxwell's equations.
  • Another participant suggests that focusing on established theories rather than discredited ones may be more beneficial for learning.
  • A third participant introduces Kaluza-Klein theory as a potential avenue for understanding the geometric representation of electromagnetism.
  • One participant agrees with the suggestion to explore Kaluza-Klein theory and emphasizes the importance of mastering modern GR before delving into alternative theories.
  • A later reply discusses the ability to represent electromagnetic theory in a differential geometric framework, contrasting the gauge covariant derivative used in electromagnetism with the covariant derivative in GR.

Areas of Agreement / Disagreement

Participants express differing views on the value of exploring alternative theories, with some advocating for a focus on established theories while others suggest that certain historical theories may still hold interest. The discussion remains unresolved regarding the effectiveness and relevance of these alternative approaches.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the validity of alternative theories and the dependence on specific definitions of geometric representations. The mathematical steps involved in the comparisons between different theories are not fully resolved.

DarthMatter
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Hi,

I'm just beginning to learn relativity, but I have a question about why gravity is so different from other forces of nature in GR. As a start, I read that Einstein tried to find a differential geometric representation of the physical universe which represents the Maxwell equations in a similar way that the curvature of spacetime in GR represents gravitation - but failed. Could someone elaborate on that, or point me to sources where I can read more about it?

Thanks in advance. :smile:
 
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DarthMatter said:
I'm just beginning to learn relativity, but I have a question about why gravity is so different from other forces of nature in GR. As a start, I read that Einstein tried to find a differential geometric representation of the physical universe which represents the Maxwell equations in a similar way that the curvature of spacetime in GR represents gravitation - but failed. Could someone elaborate on that, or point me to sources where I can read more about it?
IMHO you'd be better off spending your time learning about correct theories rather than incorrect ones! :wink:
 
Try Googling 'Kaluza-Klein theory'. It goes some way towards this.
 
+1 for what Bill_K said.

Those alternate theories have long been discredited. Don't waste your time, at least not until you've mastered modern GR in all its g[l]ory detail. :biggrin:
 
We can cast EM in a differential geometric light, in fact we can cast all gauge theories in a differential geometric light. The upshot is that the "gauge covariant derivative" ##D_{\mu} = \partial_{\mu} + ie A_{\mu}## used in EM isn't associated with a physical space-time but rather with the more abstract concept of a ##U(1)##-principal bundle, whereas the covariant derivative ##\nabla_{\mu}## in GR is of course associated with a physical space-time.

See here: http://www.nikhef.nl/~t45/ftip/Ch11.pdf and here: http://www.theorie.physik.uni-goettingen.de/~tedesco/files/connections.pdf
 
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