Dark matter -- Modified dynamics: Reaction vs. Prediction
  The dark energy-cold dark matter paradigm ($\Lambda$CDM) has gained
widespread acceptance because it explains the pattern of anisotropies observed
in the cosmic microwave background radiation, the observed distribution of
large scale inhomogeneities in detectable matter, and the perceived overall
expansion history of the Universe. It is further {\it assumed} that the cosmic
dark matter component clusters on the scale of bound astronomical systems and
thereby accounts for the observed difference between the directly detectable
(baryonic) mass and the total Newtonian dynamical mass. In this respect the
paradigm fails; it is falsified by the existence of a simple algorithm,
modified Newtonian dynamics (MOND), which explains, not only general scaling
relations for astronomical systems, but quite precisely predicts the effective
gravitational acceleration in such objects from the observed distribution of
detectable baryonic matter -- all of this with one additional universal
parameter having units of acceleration. On this sub-Hubble scale, the dark
matter hypothesis is essentially reactive, while MOND is successfully
predictive.
