Thanks for you replay Peter, but I'm still a little bit confused.
I know it, but I meant "locally" not globally.
What you mention here, looks like the Riemann normal coordinate, is it?
Can we assume that R is almost constant as in maximally symmetric spacetimes and therefore...
Can one say that every general curved spacetime, locally is maximally symmetric?
I know that one can say that every general curved spacetime is locally flat (and therefore maximally symmetric with R=0), but I'm talking about a very high curvature spacetime, where still we can consider nonzero...
Aside from isotropy and homogeneity, general relativity requires that locally
(eg, near the origin) the line element be invariant under Lorentz transformations.
FRW metric is the unique metric to present a universe which is isotropic and homogeneous in spatial part not in time. By rotational symmetry we mean isotropy and by translational symmetry we mean homogeneity of the universe. However the universe is not symmetry respect to time, if so, I think it...
Can anybody tell me what is the form and value of the Gluon Condensate in the SI units? Its value in the natural units is (300Mev)^4, but I have some problems to obtain its form in SI units (in h and c).