Constraints on the long-range properties of gravity from weak gravitational lensing

Weak gravitational lensing provides a means of testing the long-range properties of gravity. Current measurements are consistent with standard Newtonian gravity and inconsistent with substantial modifications on megaparsec scales. The data allow long-range gravity to deviate from a 1/r potential only on scales where standard cosmology would use normal gravity, but be dominated by dark matter. Thus, abnormal gravity theories must introduce two fine-tuning scales (an inner scale to explain flat rotation curves and an outer scale to force a return to Newtonian gravity on large scales), and these scales must coincidentally match the scales produced by dark matter theory after evolving the universe for 10 billion years, starting from initial conditions that are exquisitely determined from the cosmic microwave background.