Maxwell equations in terms of potentials

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Discussion Overview

The discussion revolves around the formulation of Maxwell's equations in terms of potentials, exploring their representation in various dimensions, particularly D-dimensional space. Participants examine the relationships between electric and magnetic fields and their potentials, as well as the implications of different gauges and mathematical formulations.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that the equations can be expressed in potential formulation, questioning the validity of specific mathematical identities such as ∇²A = ROT(ROT(A)) = grad(DIV(A)) - Laplace(A).
  • Others argue that ROT(ROT(A)) should be generalized for D-dimensional space, seeking clarity on how to express this in a way that aligns with the standard Maxwell equations.
  • A participant suggests that Laplace(A) must be generalized to a specific form involving second derivatives in D dimensions.
  • There is a discussion about the appropriateness of using a tensor formulation for generalizing to different dimensions, with references to the electromagnetic tensor and the Levi-Civita symbol.
  • Some participants express interest in simplifying the equations and avoiding vector products in favor of partial derivatives and sums.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct formulation of the equations or the generalization of mathematical operators for D-dimensional space. Multiple competing views remain regarding the appropriate mathematical representations and formulations.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about dimensionality and the definitions of mathematical operators. The implications of different gauges and the physical meaning of the proposed formulations are also not fully resolved.

Who May Find This Useful

This discussion may be of interest to those studying advanced electromagnetism, mathematical physics, or theoretical physics, particularly in contexts involving higher-dimensional spaces and the formulation of field theories.

olgerm
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These are Maxwell´s equations in potential formulation:
29ed508c553583e1477fc6a3681158fe.png

621ac837ee1d1d742fcf5ed3f73c033a.png


2φ = DIV(grad(φ)) . Am I right?
2A = ROT(ROT(A))=ROT(B)=grad(DIV(A))-Laplace(A) . Am I right?
In coulomb gauge in every point and at any time DIV(A)=[PLAIN]https://upload.wikimedia.org/math/4/4/1/44131cc26bd9db464d0edb7459ccca84.png. Am I right?
Where could I find Maxwell´s equations in terms of potentials without vector operator?

How must ROT (same as curl) be generalized to make the equations describe EM-field in D-dimensional space equally with these equation
##\begin{cases}
& \sum_{i=1}^D(\frac{\partial E_i}{\partial x_i})=\rho \frac{1}{{\epsilon_0}} \\
& \frac{\partial E_a}{\partial t}=\sum_{i=1}^D(\frac{\partial B_{[i;a]}}{\partial x_i})-J_a \\
& \frac{\partial B_{[a;b]}}{\partial t}=\frac{\partial E_b}{\partial x_a}-\frac{\partial E_a}{\partial x_b}\\
& \frac{\partial B_{[a;b]}}{\partial x_c}+\frac{\partial B_{[b;c]}}{\partial x_a}+\frac{\partial B_{[c;a]}}{\partial x_b}=0
\end{cases}##
,which are in terms of E and B?

φ is electripotentialfield.
E is electricvectorfield.
A is magneticpotentialvectorfield.
B is magneticvectorfield.
ρ is electriccharge density.
 
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olgerm said:
∇2φ = DIV(grad(φ)) . Am I right?
Yes
olgerm said:
∇2A = ROT(ROT(A))=ROT(B)=grad(DIV(A))-Laplace(A) . Am I right?
No. Look here: https://en.wikipedia.org/wiki/Vector_Laplacian
olgerm said:
In coulomb gauge in every point and at any time DIV(A)=
p?image=https%3A%2F%2Fupload.wikimedia.org%2Fmath%2F4%2F4%2F1%2F44131cc26bd9db464d0edb7459ccca84.png
. Am I right?
Yes
olgerm said:
Where could I find Maxwell´s equations in terms of potentials without vector operator?
You can do this yourself. Just take what you have above and replace with partial derivatives. Also, this might be useful
https://en.wikipedia.org/wiki/Covariant_formulation_of_classical_electromagnetism

Your last question is a little weird. Are interested in a 2D subset (x,y) of 3D space (x,y,z) where z is a symmetry?
 
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Khashishi said:
It seems to confirm, that ROT(ROT(A))=grad(DIV(A))-Laplace(A) .
also this http://m.wolframalpha.com/input/?i=curl+(curl+A)&x=0&y=0 seems to confirm, that ROT(ROT(A))=grad(DIV(A))-Laplace(A) . Or does ∇2 A in the second equation note Laplace(A) not ROT(ROT(A))?

Khashishi said:
Your last question is a little weird. Are interested in a 2D subset (x,y) of 3D space (x,y,z) where z is a symmetry?
I am interested about theoretical physical system with D-dimensional space. Understanding physical meaning of such system is not necessary to answer the question.
 
##\nabla^2 A## means the same thing as Laplace(A).

How many dimensions do you want to work in?
 
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Khashishi said:
How many dimensions do you want to work in?
D dimensions. Generalization must include variable D.
 
Now as I understand there are different Laplacians for vectorfield and scalarfield it makes more sense.

So are these equations in lorenz gauge
##\begin{cases}
\frac{\partial^2 A_{D_1}}{\partial t^2}=J_{D_1}\cdot k_E \cdot \pi \cdot c^2 \cdot 4+\sum_{i=1}^D(\frac{\partial^2 A}{\partial x_i \cdot \partial x_{D_1}}) \cdot c^2-ROT(ROT(A)) \cdot c^2\\
\frac{\partial^2 \phi}{\partial t^2}=\rho \cdot k_E \cdot \pi \cdot 4+\sum_{i=1}^D(\frac{\partial^2 \phi}{\partial x_i^2})\\
\frac{\partial \phi}{\partial t}=\sum_{i=1}^D(\frac{\partial A_i}{\partial x_i}) \cdot c^2\\
F_E=q\cdot(\sum_{i=1}^D(v_i \cdot \frac{\partial A_i}{\partial x_{D_1}})-\frac{\partial A_{D_1}}{\partial t}-\frac{\partial \phi}{\partial x_{D_1}})
\end{cases}##
?

But what must ROT(ROT(A)) equal to in D-dimensional space so that the Maxwell equations were equal with these
##\begin{cases}
& \sum_{i=1}^D(\frac{\partial E_i}{\partial x_i})=\rho \frac{1}{{\epsilon_0}} \\
& \frac{\partial E_a}{\partial t}=\sum_{i=1}^D(\frac{\partial B_{[i;a]}}{\partial x_i})-J_a \\
& \frac{\partial B_{[a;b]}}{\partial t}=\frac{\partial E_b}{\partial x_a}-\frac{\partial E_a}{\partial x_b}\\
& \frac{\partial B_{[a;b]}}{\partial x_c}+\frac{\partial B_{[b;c]}}{\partial x_a}+\frac{\partial B_{[c;a]}}{\partial x_b}=0
\end{cases}##
equation?
I also want the equation system to be formed as short and easy as possible. What gauge you recommend me to choose? Any ideas how to simplify the equations?
 
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I have hypothesis, that Laplace(A) must be generalized to be equal to ## 2\cdot\frac{\partial^2 A_{D_1}}{\partial x_{D_1}^2}-\sum_{i=1}^D(\frac{\partial^2 A_{D_1}}{\partial x_i^2})## .
Can anybody check if it is correct?
 
You know what the electromagnetic tensor is? You should use a tensor formulation if you want to generalize to different dimensions. I asked what dimension you wanted to work in because it affects the answer. Cross product only really works in 3 or 7 dimensions. You might want to use the Levi-Civita symbol.
 
Khashishi said:
You know what the electromagnetic tensor is? You should use a tensor formulation if you want to generalize to different dimensions.
I got the equations in E and B formulation from Maxwell equations in electromagnetic tensor formulation.

The equations should not contain vector products on operators, but partial derivatives and sums. D must be a variabe, that can be equal to any natural number.
 
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  • #10
I have got my answer. Correct equation system is:
##\begin{cases}
\frac{\partial^2 A_{D_1}}{\partial t^2}=J_{D_1}\cdot k_E \cdot \pi \cdot 4+\sum_{i=1}^D(\frac{\partial^2 A_{D_1}}{\partial x_i^2}) \cdot c^2\\
\frac{\partial^2 \phi}{\partial t^2}=\rho \cdot k_E \cdot c^2 \cdot \pi \cdot 4+\sum_{i=1}^D(\frac{\partial^2 \phi}{\partial x_i^2})\\
\frac{\partial \phi}{\partial t}=\sum_{i=1}^D(\frac{\partial A_i}{\partial x_i}) \cdot c^2\\
F_E=q\cdot(\sum_{i=1}^D(v_i \cdot \frac{\partial A_i}{\partial x_{D_1}})-\frac{\partial A_{D_1}}{\partial t}-\frac{\partial \phi}{\partial x_{D_1}})
\end{cases}##
 

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