- All cosmological models are characterized by `test particles',
which are galaxies that are distributed in a homogeneous and
isotropic manner in accordance with the CP.
- Open Models are characterized by
< 1, negative
curvature (k = -1), hyperbolic geometry, a deceleration parameter
q < 1/2, and infinite spatial extent (ignoring topology).
- Closed Models are characterized by
> 1, positive curvature
(k = 1), spherical geometry, a deceleration parameter q > 1/2 and
finite spatial extent.
- Flat Models are characterized by
= 1, flat geometry with
no curvature (k = 0), infinite spatial extent, a deceleration
parameter q = 1/2 and with an age corresponding to
Age = H0-1, since the Hubble Constant is