title: Nonlocal cosmology.
abstract: We explore nonlocally modified models of gravity, inspired by quantum loop corrections, as a mechanism for explaining current cosmic acceleration. These theories enjoy two major advantages: they allow a delayed response to cosmic events, here the transition from radiation to matter dominance, and they avoid the usual level of fine-tuning; instead, emulating Dirac's dictum, the required large numbers come from the large time scales involved. Their solar system effects are safely negligible, and they may even prove useful to the black hole information problem.
authors.affiliation: California Institute of Technology, Pasadena, California 91125, and Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA. deser@brandeis.edu
authors.forename: S
authors.initials: S
authors.lastname: Deser
authors.forename: R P
authors.initials: RP
authors.lastname: Woodard