The electromagnetic theory in large part is metric independent. It is called premetric electrodynamics. The energy-momentum tensor is a mapping of volume trivectors into one-forms. When F and G are well known two-forms describing the electromagnetic field, V is a volume trivector, the energy momentum tensor of the electromagnetic field is the following linear mapping \documentclass[12pt]{minimal}
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\begin{document}$$V \rightarrow T(V) = \frac{1}{2} [G\lfloor(V \lfloor F) - F\lfloor(V \lfloor G)]$$\end{document}.