BCJ Relations and the Classical Double Copy


The BCJ relations give a formal realization of the $(\text{gravity}) = (\text{gauge theory})^2$ correspondence, via a relationship between graviton and gluon amplitudes. In this talk, I reviewed the current understanding of the BCJ relations for tree-level amplitudes, and the conjectured extension to all loop orders. I also described ongoing research work into a classical consequence of gauge/gravity duality, the double copy relationship between Einstein gravity and Yang-Mills theory.