robert j. kolker wrote:
Van Jacques wrote:
The theoretical basis of the mechanics of continua is the
first field theory, and is often neglected. We can learn a lot
about fields from this theory.
Historically, Faraday conceived of the electrostatic fields producing
lines of stress in a viscoelastic continous medium (hello aether!).
Maxwell continued along these lines.
Bob Kolker
When I say field theory, I mean a theory based on Hamilton's principle
of stationary action, and a Lagrangian which depends on some fields,
so that one can use the mathematical apparatus of this canonical theory
to find the energy momentum tensor T and the conservation eqns div(T) =
0.
The conservation of momentum is the eqn. of motion.
All basic physics can be put on this basis (motion of matter, the EM
field, GR), and it is the basis for those doing quantum field theory,
string theory, etc.
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