§Further
remarks:
3.From Raychaudhury eq., since
, an accelerated phase is achieved whenever P(r) < -r/3.
4.Remark 3 is
only valid in GR. Remarks 1 and 2, however, are only based on conservation of energy. This is also valid
(locally) in inhomogeneous models along flow lines. Thus Remarks 1
and 2 are valid in any gravity theory, as well as (locally) in
inhomogeneous models.
5.Any point rL is a de
Sitter attractor (repeller) of the evolution during expansion if r+P(r)<0 (>0) for r< rL and r+P(r)>0
(<0) for r> rL.