  Quantum gravity effects are traditionally tied to short distances and high
energies. In this essay we argue that, perhaps surprisingly, quantum gravity
may have important consequences for the phenomenology of the infrared. We
center our discussion around a conception of quantum gravity involving a notion
of quantum spacetime that arises in metastring theory. This theory allows for
an evolution of a cosmological Universe in which string-dual degrees of freedom
decouple as the Universe ages. Importantly such an implementation of quantum
gravity allows for the inclusion of a fundamental length scale without
introducing the fundamental breaking of Lorentz symmetry. The mechanism seems
to have potential for an entirely novel source for dark matter/energy. The
simplest observational consequences of this scenario may very well be residual
infrared modifications that emerge through the evolution of the Universe.
