A Nonlocal Metric Realization of MOND

MOND is a phenomenological model which modifies the extreme weak field regime of Newtonian gravity so as to explain galactic rotation curves without dark matter. If correct, it must be the non-relativistic, static limit of some relativistic modified gravity theory. I show how the only possible metric-based modification of gravity is nonlocal, and I construct the action using the Tully-Fisher relation and weak lensing. Then I explore the consequences of this model for cosmology. This talk is based on four arXiv papers:1106.4984,1405.0393,1608.07858 and 1804.01669.