  We propose that there is a regime of quantum gravity phenomena, for the case
that the cosmological constant is small and positive, which concerns phenomena
at temperatures below the deSitter temperature, or length scales larger than
the horizon. We observe that the standard form of the equivalence principle
does not apply in this regime; we consider instead that a weakened form of the
equivalence principle might hold in which the ratio of gravitational to
inertial mass is a function of environmental and global parameters. We consider
possible principles to determine that function. These lead to behaviour that,
in the limit of hbar to zero and the speed of light is taken to infinity,
reproduces the modifications of Newtonian dynamics first proposed by Milgrom.
Thus MOND is elucidated as coding the physics of a novel regime of quantum
gravity phenomena.
  We propose also an effective description of this regime in terms of a
bi-metric theory, valid in the approximation where the metric is static. This
predicts a new effect, which modifies gravity for radial motions.
