• gravitation;
  • cosmology: theory;
  • dark matter


I describe a tensor–vector–scalar theory that reconciles the galaxy-scale success of modified Newtonian dynamics (MOND) with the cosmological scale evidence for cold dark matter (CDM). The theory provides a cosmological basis for MOND in the sense that the predicted phenomenology only arises in a cosmological background. The theory contains an evolving effective potential, and scalar field oscillations in this potential comprise the CDM; the de Broglie wavelength of these soft bosons, however, is sufficiently large that they cannot accumulate in galaxies. The theory predicts, inevitably, a constant anomalous acceleration in the outer Solar system, which, depending upon the choice of parameters, can be consistent with that detected by the Pioneer spacecrafts.