Cosmologists at Perimeter Institute seek to help pin down the constituents and history of our universe, and the rules governing its origin and evolution. Many of the most interesting clues about physics beyond the standard model (e.g., dark matter, dark energy, the matter/anti-matter asymmetry, and the spectrum of primordial density perturbations], come from cosmological observations, and cosmological observations are often the best way to test or constrain a proposed modification of the laws of nature, since such observations can probe length scales, time scales, and energy scales that are beyond the reach of terrestrial laboratories.
The holographic duality gives a one-to-one mapping between consistent theories of gravity with AdS_d ground state, and conformal field theories in d-1 dimensions. Since the latter are unambiguously well-defined, we can use their defining properties to prove rigorous, model-independent theorems covering all quantum gravity theories with negative cosmological constant. Taking d=3, I will prove in this talk that every two-dimensional CFT contains a primary perator of weight less than C /12 + 0.473695, where C is the sum of right- and left-moving central charges. Using the AdS/CFT dictionary, this establishes that every theory of quantum gravity in asymptotically AdS space contains some state of mass less than 1 / (4 G), above and beyond the universal sector of boundary metric excitations.