What are the existence of solutions to Maxwell's equations?

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Discussion Overview

The discussion revolves around the existence of solutions to Maxwell's equations, exploring the necessary and sufficient conditions for their existence, particularly in relation to charge conservation and boundary conditions. Participants reference mathematical literature and draw analogies to other physical systems.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire about references related to the existence of solutions to Maxwell's equations.
  • One participant notes that charge conservation is a necessary condition for the existence of Maxwell's equations but questions if it is also sufficient.
  • Another participant suggests that reasonable boundary conditions are also required for the existence of solutions and mentions the Cauchy problem in partial differential systems.
  • A participant challenges the availability of rigorous mathematical literature on the existence of field equations, specifically questioning the sufficiency of charge conservation for Maxwell's equations and the conservation of the energy-momentum tensor for Einstein's field equations.
  • One participant argues that charge conservation is a necessary condition linked to gauge symmetry and highlights the importance of using the covariant derivative in the context of general relativity.
  • Another participant references a specific theorem regarding the div-curl system, asserting that certain conditions, including charge continuity, are sufficient for existence.

Areas of Agreement / Disagreement

Participants express differing views on whether charge conservation is sufficient for the existence of Maxwell's equations, with some asserting it is necessary while others propose it may also be sufficient. The discussion remains unresolved regarding the sufficiency of these conditions.

Contextual Notes

Participants reference various mathematical frameworks and theorems, indicating that the discussion may depend on specific definitions and assumptions regarding the systems being analyzed.

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Are there any references?
 
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A. Sommerfeld, Lectures of Theoretical Physics, vol. 3
 
Thank @ vanhees71 . However , I don't find the existence conditions, only found uniqueness .
Electrodynamics. Lectures on Theoretical Physics, Vol. 3 by Arnold Sommerfeld
 
Thank all replies :) @DrClaude @vanhees71
We all know that charge conservation is one of necessary conditions for the existence of Maxwell equations!
I want to know: is charge conservation one of sufficient conditions for the existence of Maxwell equations?
 
Together with reasonable boundary conditions of course. I guess, there is rigorous math literature on this subject. Usually the Cauchy problem of all kinds of partial-differential systems occurring in physics is an interesting topic for mathematical physicists. Particularly famous is the question about existence and uniqueness for General Relativity.
 
vanhees71 said:
Together with reasonable boundary conditions of course. I guess, there is rigorous math literature on this subject. Usually the Cauchy problem of all kinds of partial-differential systems occurring in physics is an interesting topic for mathematical physicists. Particularly famous is the question about existence and uniqueness for General Relativity.

rigorous math literature ? Really ?
By bing.com, I cannot find the existene of field equations.
For electromagnetic field, is the charge conservation (##\partial_\alpha J^\alpha=0##) one of sufficient conditions for the existence of Maxwell equations?
For gravitational field, is the soure's conservation (##\nabla_\alpha T^{\alpha\beta}=0##) one of sufficient conditions for the existence of Einstein field equations?

As an analogy, for ##\nabla\cdot \mathbf{u}=\rho, \nabla\times \mathbf{u}=\mathbf{S}##, is ##\nabla\cdot \mathbf{S}=0## one of sufficient conditions for the existence of div-curl system?

I think so! They are all sufficient conditions.

The EXISTENCE should be talked, e.g. http://www.claymath.org/millennium-problems/navier–stokes-equation
 
Last edited:
Charge conservation is a necessary condition for the consistency of the Maxwell equations. It's a Bianchi identity of gauge symmetry. For the gravitational field the energy-momentum tensor, which is necessarily symmetric, as a source is necessarily locally conserved. The correct equation is ##\nabla_{\mu} T^{\mu \nu}=0##, i.e., you must use the covariant derivative of the tensor-field components. This is again the consequence of a Bianchi symmetry of gauge symmetry of GR (general covariance).
 
For single div--curl system, i.e. div u = f, curl u = B, theorem 3.3 in this paper (
Junichi Aramaki, L^p Theory for the div-curl System, Int. Journal of Math. Analysis, Vol. 8, 2014, no. 6, 259 - 271. http://dx.doi.org/10.12988/ijma.2014.4112 ) says that : div B =0 is one of sufficient conditions of existence.

Maxwell equations are double div--curl systems. I think that the charge continuity equation is also one of sufficient conditions of existence.
 

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