The discussion revolves around deriving the energy-momentum tensor for electromagnetism from a given Lagrangian. The subject area includes classical electrodynamics and field theory.
Some participants have provided references to textbooks and resources that may aid in understanding the concepts involved. There is an ongoing exploration of the relationship between the Lagrangian and the energy-momentum tensor, with no explicit consensus reached yet.
Participants mention the absence of gravity and its implications for the derivation, as well as the need for further resources to clarify advanced topics in the discussion.
Thanks but can you suggest a book or something where i can understand this better, a good explanatory text perhaps.dextercioby said:1. In the absence of gravity T follows from L from the Noether theorem and the Belinfante symmetrization procedure.
2. In the presence of gravity T follows from L directly (even without the coupling to charged scalar matter).
Both parts are (advanced) textbook stuff in either of the 3 subjects: classical electrodynamics or classical/quantum field theory (1.), general relativity (2.)
Was this helpful for you ? Either 1. or 2. should give you a starting point.
dextercioby said:For the GR stuff, check section 28, page 54 from Dirac's brochure on GR (I chose Dirac's book as being the easiest path to the wanted reference).
For SR http://en.wikipedia.org/wiki/Belinfante–Rosenfeld_stress–energy_tensor. I can't find a book reference.