The graphics from Pullin's
talk are here in seven web pages. Click on the indicated subject to go to the relevant
page. You can also download a
Pullin began the workshop with a succinct account of GR. He
pointed participants to more information in
Wikipedia, noting especially
no-nonsense introduction, and then he
outlined his talk.
pg. 2 He
gave a one-slide summary
of the special relativity needed to understand general relativity, and
then showed the essence of GR:
gravity is curvature of
spacetime and the spacetime
interval is the measure of "distance".
pg. 3 To describe
curved space you need tensors.
Trajectories are curves
parameterized by the proper time, and absent forces, these are straight
lines in spacetime. For vector algebra you need a metric; for vector
calculus you need the
tell how matter curves spacetime. The curvature affects physics.
You need to know how curvature
shows up in the mathematics: Ricci tensor and curvature scalar.
relates physics to curved space; he shows the weak field metric outside
pg. 5 There are
singularities in this
metric. One is an artifact of choice of coordinates; the other implies
there are black holes. In
the weak field limit there is an effective potential that accounts for
the precession of the perihelion of Mercury. This effective
potential is an
"exterior" solution, not valid in close.
pg. 6 The weak-field
metric implies there should be gravity
waves. The possibility of such waves can also be seen by using
Kruskal coordinates and obtaining a
wave equation. He then uses a Green's function to obtain a
solution of this wave equation.
Summary: Gravity is the
deformation of geometry; Einstein's equations describe how geometry is
deformed; solutions of these equations describe well the effects of weak
fields and predict new phenomena for strong fields; the equations have
wave-like solutions, but the lowest contribution is quadrupolar.