This work discusses the
problem of the apparently non-symmetric form of the electromagnetic fields’ energy-momentum tensor,
which is obtained from the variational principle. The analysis treats differently radiation fields and bound fields. This distinction has a solid experimental
basis where the hydrogen atom proves that radiation fields and bound fields
have a different spin and a different parity. A direct calculation proves that
in the case of radiation fields, the variational principle yields the well
known symmetric energy momentum tensor and the problem does not exist.
Comay, E. (2015) Interrelations between Mathematics and Experiment in the Present Structure of Quantum Electrodynamics. Open Access Library Journal, 2, e2211. http://file.scirp.org/pdf/OALibJ_2016072610462207.pdf