  Based on superfluid behavior of a (boson) dark matter as the light itself, a
unified model for dark matter and quintessence is proposed. Inspired by (O'Dell
et al. 2000) which in an exciting study showed that particular configurations
of intense off-resonant laser beams (simulate the Bose-Einstein condensate) can
give rise to an attractive 1/r interatomic potential, I infer electromagnetic
origin of inertia and gravity. Time varying dark components result in time
varying electromagnetic fine structure constant (alpha) or the quantities given
in its definition (even an invariant alpha would not exclude the possibility
that these values might be changing in ratio to one another), in either case
variable speed of light (VSL) with dc/dt < 0. According to (Wetterich 2003a) a
bound R = delta_alpha(z = 0.13)/delta_alpha(z = 2) < 0.02 strongly favors
quintessence with a time varying equation of state w = p/rho, where the value
of (1+w) at present is substantially smaller than for z = 2 and equivalently
compressibility is increased in the medium and this process has significant
influences on the process of structure formation. These models typically
require quintessence coupling to a photon which would require large coupling
between non-baryonic dark matter and the scalar field therefore consistent with
our model, quintessence may couple to both non-baryonic dark matter and
radiation. Wetterich (2003b) observe that Omega_quint does not affect the time
evolution of the fundamental couplings and alpha depends only on the equation
of state w and this fascinating result further support the common essence of
light and boson dark matter.
