Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I noticed that the Lorenz gauge term is represented by partial derivatives acting on the four-potential. Is it possible that the Lorenz gauge term could somehow be a similar object that belongs to the electromagnetic fields?

share|cite|improve this question
Related: – Qmechanic Mar 15 '14 at 17:07
up vote 2 down vote accepted

The Lorenz gauge term $\partial_\mu A^{\mu}$, or equivalently the expression (in $c=\hbar=1$)

$$\nabla \cdot \vec{A} + \frac{\partial \phi}{\partial t} $$

as a scalar quantity in its own right has no physical significance. Furthermore, the $4$-potential is not an object "that belongs to the electromagnetic fields," as the OP stated. The field $A_\mu$ is a quantity from which the electromagnetic fields may be derived; for example

$$\vec{E} = - \left( \nabla \phi + \frac{\partial \vec{A}}{\partial t}\right).$$

On the other hand, the quantity $\partial_\mu A^\mu$ is used for gauge fixing, we do not derive from it the electromagnetic fields.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.