How Does Gauge Symmetry Allow Solutions to the Lorentz Gauge Condition?

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Discussion Overview

The discussion revolves around the concept of gauge symmetry in classical field theory, specifically in the context of electromagnetism and the Lorentz gauge condition. Participants explore how the freedom to modify the 4-potential through the addition of a gradient of a smooth function relates to finding solutions that satisfy the Lorentz gauge condition (∂μAμ = 0), including considerations of boundary conditions.

Discussion Character

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

Main Points Raised

  • One participant notes that gauge symmetry allows for the addition of a gradient of a smooth function to the 4-potential without altering the physics, raising the question of how this leads to solutions satisfying the Lorentz gauge condition.
  • Another participant mentions that the gauge in question is commonly referred to as the Lorenz gauge, although there is a discussion about the correct terminology (Lorenz vs. Lorentz).
  • A participant provides a reference to a paper discussing the terminology and its implications, suggesting that it is a good resource despite its formatting.
  • Further inquiry is made into the conditions required for a modified 4-potential to satisfy the Lorenz gauge condition, prompting questions about the existence of a suitable function f.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the terminology of the gauge condition, with some favoring "Lorenz" and others "Lorentz." The discussion remains unresolved regarding the specific conditions under which a function f can be found to satisfy the Lorenz gauge condition.

Contextual Notes

There are unresolved assumptions regarding the boundary conditions and the specific form of the function f that would satisfy the Lorenz gauge condition. The discussion also reflects varying interpretations of gauge terminology.

Who May Find This Useful

Students and researchers interested in classical field theory, gauge theories, and electromagnetism may find this discussion relevant, particularly those exploring the implications of gauge symmetry and the Lorentz gauge condition.

QuasarBoy543298
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hi, I'm currently taking a classical field theory class (electromagnetism in the language of tensors and actions and etc) and we have just encountered the gauge symmetry, that is for the 4 vector potential we can add a gradient of some smooth function and get the same physics (if we take Aμ → Aμ + ∂μf the actions stays the same, except some irrelevant constant).
now after that long preview, my question is - how can we conclude from that freedom that we can find a solution for the field A, with any boundary conditions, that satisfies the Lorentz gauge ( ∂μAμ = 0)?
 
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That is done on most textbooks. It is the Lorenz gauge.
 
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saar321412 said:
how can we conclude from that freedom that we can find a solution for the field A, with any boundary conditions, that satisfies the Lorentz gauge ( ∂μAμ = 0)?
Assume that you have a 4-potential ##A_\mu## that does not satisfy the Lorenz gauge condition and write down a new 4-potential ##A'_\mu = A_\mu + \partial_\mu f##. What is the condition on ##f## in order for ##A'_\mu## to satisfy the Lorenz gauge condition? Can you find such a function?
 
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