Motivated by the BCJ double copy in quantum field theory, we demonstrate a correspondence between perturbative solutions of classical scalar, gauge and gravity theories.
First, we show that classical Yang-Mills radiation from a system of colored particles can be obtained from classical bi-adjoint scalar radiation emitted by a corresponding system of bi-adjoint colored particles, via a simple set of color-kinematic substitution rules. This completes a two-fold double copy that can be used to generate classical gravitational radiation emitted by a collection of dynamical point sources, from the simpler bi-adjoint scalar radiation.
Next, we extend the classical double copy to spinning sources, thus bringing it closer to the astrophysically relevant case of compact binaries. Here, we compute Yang-Mills radiation generated by a system of spinning color charges. We show that the color-kinematic replacements can be used to map this onto classical gravitational radiation emitted by a system of interacting spinning masses. If this classical double copy correspondence persists to higher orders in perturbation theory, it suggests the possibility of vastly simplifying the calculation of gravitational radiation, in particular, that from colliding compact objects, recently discovered by LIGO.
Thesis Advisor: Walter Goldberger