Why do we use covariant formulation in classical electrodynamics?

  • Context: Graduate 
  • Thread starter Thread starter m_prakash02
  • Start date Start date
  • Tags Tags
    Classical Covariant
Click For Summary

Discussion Overview

The discussion revolves around the use of covariant formulation in classical electrodynamics, specifically regarding Maxwell's equations. Participants explore the nature of covariant and contravariant formulations, their interrelation, and the implications for understanding electromagnetic theory.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions the exclusive use of covariant formulation for Maxwell's equations and inquires about the existence of contravariant formulations.
  • Another participant suggests that using the metric tensor allows for the conversion between covariant and contravariant formulations.
  • A different viewpoint emphasizes the Faraday tensor as an exact two-form, with the four-potential understood as a one-form.
  • Some participants assert that the term "covariant formulation" refers to the use of tensors, indicating that both covariant and contravariant tensors can be utilized as necessary.
  • A participant recommends a resource, specifically Vol. 2 of Landau and Lifshitz, as a valuable text for understanding classical electrodynamics from a relativity perspective.
  • Another participant notes that covariance is a common characteristic of equations derived from the least-action principle.

Areas of Agreement / Disagreement

Participants express varying views on the necessity and application of covariant versus contravariant formulations in electrodynamics. There is no consensus on the exclusive use of one over the other, and the discussion remains open-ended regarding the implications of these formulations.

Contextual Notes

The discussion includes assumptions about the definitions and interrelations of covariant and contravariant tensors, as well as the implications of using the least-action principle in formulating equations. These aspects remain unresolved.

Who May Find This Useful

This discussion may be useful for graduate physics students, researchers in classical electrodynamics, and those interested in the mathematical foundations of electromagnetic theory.

m_prakash02
Messages
3
Reaction score
1
TL;DR
Why exactly do we use only covariant formulation to write Maxwell's equations? Is there a specific reason?
I am a graduate physics student currently studying electrodynamics as a core paper. I want to know why exactly do we use only covariant formulation for writing Maxwell's equations? Or do we also use contravariant formulation (i.e., if something like that even exists)?
 
Physics news on Phys.org
Using metric tensor a covariant formula is written as a contra variant formula and vice versa.
 
  • Like
Likes   Reactions: m_prakash02
I'd say the most "natural" understanding of the Faraday tensor is as an exact two-form,
$$F=\mathrm{d} \wedge A,$$
where the four-potential ##A## is understood as a one-form.
 
  • Like
Likes   Reactions: m_prakash02
m_prakash02 said:
TL;DR Summary: Why exactly do we use only covariant formulation to write Maxwell's equations? Is there a specific reason?

I want to know why exactly do we use only covariant formulation for writing Maxwell's equations? Or do we also use contravariant formulation (i.e., if something like that even exists)?
“Covariant formulation” just means using tensors. You can use both covariant and contra variant tensors as needed.
 
  • Like
Likes   Reactions: m_prakash02, vanhees71 and Ibix
Dale said:
“Covariant formulation” just means using tensors. You can use both covariant and contra variant tensors as needed.
Thanks for the reply! Could you please suggest me some resources for further reading?
 
  • Like
Likes   Reactions: vanhees71
The best "relativity-first approach" to classical electrodynamics imho is Vol. 2 of Landau and Lifshitz (Classical Field Theory). It's also a very nice intro to General Relativity.
 
  • Like
Likes   Reactions: m_prakash02, Dale and PeroK
covariance is a common feature of least-action-principle generated equations
 
  • Like
Likes   Reactions: m_prakash02 and vanhees71

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 9 ·
Replies
9
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 1 ·
Replies
1
Views
711
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K