🚀 go-pugleaf

Mitsu - in response to earlier question of yours - asymptotic flatness does
make formal sense in many matrics lie Schwarzschild, for example, it means
take the coordinate r to infinity ("metrics" not "matrics").

A key idea in classical general relativity is the equivalence principle and
that is closely related to local flatness (not to be confused with
asymptotic flatness). All metrics must be locally flat everywhere (except
singularity) - it means there are local free-float inertial frames - gravity
is eliminated for an LIF observer - if no electrical forces etc. the LIF
observer is in free float same as astronaut falling around earth in
elliptical orbit (I should have said falling toward center of mass of earth
with finite conserved orbital angular momentum making the ellipse with
center of mass a focus of the ellipse - for very accurate measurements the
observer can feel inhomogeneous tidal forces so that over time she is moving
across a sequence of LIF's - LIF is a relative idea dependent on sensitvity
of measurements - that is, a given LIF for a given sensitivity only exists
over a finite region of Lorentzian curved spacetime - consistent with the
mathematical idea of a Minkowski-flat tangent plane - point of tangency
corresponding to the finite region of the LIF - because of this locality
property (not same as locality in sense of Bell's theorem) the symmetry
group of the tnagent plane should be the local Loretnz group sans the
translation group (Poincare group is semi-direct product of Lorentz and
global translation group - that's why I questioned John Baez's remark that
symmetry group of tangent plane was Poincare group.

By the way big Relativistic COnference at UCB sun Dec 13 9am Zellerbacj
lasting till Dec 18.