Gravitational energy as dark energy: Towards concordance cosmology
  without Lambda
  I briefly outline a new physical interpretation to the average cosmological
parameters for an inhomogeneous universe with backreaction. The variance in
local geometry and gravitational energy between ideal isotropic observers in
bound structures and isotropic observers at the volume average location in
voids plays a crucial role. Fits of a model universe to observational data
suggest the possibility of a new concordance cosmology, in which dark energy is
revealed as a mis-identification of gravitational energy gradients that become
important when voids grow at late epochs.
