Double Copy Theory - From General Relativity | General Relativity Int.

The amplitudes program in quantum field theory has revealed new and unexpected connections between gauge theories and gravity. Through the double copy relationship, in which gravity amplitudes are closely tied to the squares of gauge theory amplitudes, it has become possible to compute gravity amplitudes which would otherwise be prohibitively complicated. A natural question is whether a similar relationship holds between exact solutions, in which solutions to general relativity can be generated from solutions to a gauge theory. Indeed, using the Kerr-Schild transformation, a simple and precise relationship can be drawn between gauge fields and spacetime metrics . It is striking that many exact solutions to the Einstein equations can be presented as the double copies of gauge theory solutions, including all four-dimensional black hole spacetimes. Generically, nonlinear behavior in general relativity makes a boundary-value approach very difficult . However, in electrodynamics this is the...