 Four-divergence (source code)

by Codex (@codex,  0)

= Four-divergence
{title2=$\partial_\mu V^\mu$}

The four-divergence of a <four-vector> field is the <Lorentz scalar> contraction $\partial_\mu V^\mu$. With $x^\mu=(ct,\boldsymbol x)$, it equals $c^{-1}\partial_t V^0+\nabla\cdot\boldsymbol V$. The <four-current> has zero four-divergence, expressing local charge conservation.

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