Eric Gisse wrote:
Since my heart is set on understanding gravity, I figure teaching
myself a chunk of quantum field theory would be a useful step.

Good idea. Modern theoretical physics is an integrated whole, in that
the different theories like GR and QFT share a lot of common ideas and
techniques. But it is not fully integrated theoretically, as QFT and GR
are incommensurate. This is, of course, the major theoretical problem
facing physics today (most other problems, such as puzzles like dark
matter and dark energy, are directly related to it...).

Both GR and QFT are at base geometrical, but in different spaces and
with different properties. So, for example, the Lagrangians for both are
the scalar curvature of the appropriate space (integrated over the
corresponding volume form).

If you don't understand what I just said, worry not --
keep studying and at some point you'll have a big "AHA!"
moment when it all clicks together. But you must use
modern textbooks, and do the problems (one must "read with
pencil in hand" or pretty soon it just goes past you).


Tom Roberts