# Maxwell invariants

20 Dec 2017in contrast to the CQWs of the last two weeks the question of invariants of the Maxwell-field is a bit different: Naturally, \(F_{\mu\nu}\) is antisymmetric due to gauge invariance and therefore trace-free, \(F_\mu^\mu=0\), and \(F_{\mu\nu}F^{\mu\nu}\) is the Lagrange-density \(\mathcal{L}\) of the free Maxwell-field. can you construct more invariants, including the dual field tensor, and say something about their physical interpretation?