  It is shown that holographic cosmology implies an evolving Hubble radius
$c^{-1}\dot{R}_H = -1 + 3\Omega_m$ in the presence of a dimensionless matter
density $\Omega_m$ scaled to the closure density $3H^2/8\pi G$, where $c$
denotes the velocity of light and $H$ and $G$ denote the Hubble parameter and
Newton's constant. It reveals a dynamical dark energy and a sixfold increase in
gravitational attraction to matter on the scale of the Hubble acceleration. It
reproduces the transition redshift $z_t\simeq 0.4$ to the present epoch of
accelerated expansion and is consistent with $(q_0,(dq/dz)_0)$ of the
deceleration parameter $q(z)=q_0+(dq/dz)_0z$ observed in Type Ia supernovae.
