Why did covariant nu change sides with mu in the inhomogenous maxwell equation?

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The discussion centers on the transformation of covariant "nu" to contravariant in the inhomogeneous Maxwell equations when taking derivatives. The field strength tensor is defined in equation (1.1), and the inhomogeneous equations are expressed in equation (1.2). The confusion arises from the derivative operation applied to equation (1.3), where the author mistakenly thought the derivative was with respect to "nu" instead of "mu." The resolution clarifies that the author actually commuted the derivatives, which explains the change in indices. This highlights the importance of understanding the properties of covariant and contravariant indices in tensor calculus.
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[SOLVED] Inhomogenous maxwell equation

Homework Statement


In relativistic notation , the field strenght tensor can be expressed as (A is the vector potential) as on eq.(1.1) .

The inhomogenous Maxwell equations can be written as on eq.(1.2) .
Why did covariant "nu" changed sides with "mu" and become contravariant on the second term of left hand side of the equation 1.2 when one take the derivative of eq.(1.3) by
\partial_{\nu}?


Homework Equations


F^{\mu\nu}=\partial^{\mu}A^{\nu}-\partial^{\nu}A^{\mu} (1.1)

\partial_{\mu}\partial^{\mu}A^{\nu}-\partial^{\nu}\partial_{\mu}A^{\mu}=\frac{4\Pi}{c}J^{\nu} (1.2)

\partial_{\mu}F^{\mu\nu}=\frac{4\Pi}{c}J^{\nu} (1.3)

The Attempt at a Solution


I tried to contract all terms in the eq.(1.2) , however , I couldn't find a quantitative way to solve the problem .
 
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ercagpince said:
Why did covariant "nu" changed sides with "mu" and become contravariant on the second term of left hand side of the equation 1.2 when one take the derivative of eq.(1.3) by
\partial_{\nu}?

The author didn't take the derivative \partial_{\nu}, he took the derivative \partial_{\mu}. In the second term of the left hand side he simply commuted \partial^{\nu} and \partial_{\mu}.
 
thanks a lot!
 
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