Our understanding of nature is presently split into two vastly different domains: Quantum theory describes physics at the smallest scales (atoms and subatomic particles). The theory of relativity applies at the largest scales (gravity, space, and time). Quantum gravity seeks to unify these disparate realms into one description of nature, based on a single set of principles.
Perimeter researchers pursue many approaches to this challenge, including loop quantum gravity, spin foam models, string theory, causal set theory, shape dynamics, twistor theory, and asymptotic safety. They also seek ways to test and validate ideas about quantum gravity through experimentation. Quantum gravity overlaps with other Perimeter research areas including cosmology, particle physics, and quantum foundations.