Hubble Energy
  Light received from a cosmological source is redshifted with an apparent loss of energy, a problem first pointed out by Edwin Hubble in 1936. A new type of energy called Hubble Energy is introduced to restore the principle of energy conservation. The energy has no inertial or gravitational effect but retards radial motion in a manner consistent with the anomalous acceleration experienced by the Pioneer probes leaving the solar system. The energy is predicted to have important effects on the scale of galaxies, and some of these effects are qualitatively examined: for example, with Hubble Energy, flat rotation curves are found to be an inevitable consequence of spiral galaxy formation. The Hubble Energy is incorporated into the Friedmann Equation and shown to add a term similar to the cosmological term, with a magnitude of order 10^-35 s^-2. 
Alasdair Macleod