Testing whether cosmic acceleration arises from modifications to general relativity rather than a cosmological constant. Includes f(R) gravity, galileons, and massive gravity theories with observational constraints from structure formation.
Core Beliefs
General relativity may require modification at cosmological scales
Dark energy could be an artifact of incomplete gravitational theory
Viable modified gravity must pass Solar System and binary pulsar tests
Methods
Parameterized post-Friedmann frameworks
Large-scale structure formation simulations
Gravitational wave observations as theory discriminants