  We characterize a class of simple FRW models filled by both dark energy and
dark matter in notion of a single potential function of the scale factor
$a(t)$; $t$ is the cosmological time. It is representing potential of
fictitious particle - Universe moving in 1-dimensional well $V(a)$ which the
positional variable mimics the evolution of the Universe. Then the class of all
dark energy models (called a multiverse) can be regarded as a Banach space
naturally equipment in the structure of the Sobolev metric. In this paper we
explore notion of $C^{1}$ metric introduced in the multiverse which measure
distance between any two dark energy models. If we choose cold dark matter as a
reference one then we can find how so far apart are different models offering
explanation of present accelerating expansion phase of the Universe. We
consider both models with dark energy (models with the generalized Chaplygin
gas, models with variable coefficient equation of state
$w_{X}=\frac{p_{X}}{\rho_{X}}$ parameterized by redshift $z$, models with
phantom matter) as well as models basing on some modification of the Friedmann
equation (Cardassian models, Dvali-Gabadadze-Porati brane models). We argue
that because observational data still favor the $\Lambda$CDM model all
reasonable dark energy models should belong to the nearby neighborhood of this
model.

General Relativity and Quantum Cosmology