Physics

Gravitation

Gravitational field

Scattering amplitude

Musical

General relativity

Visual arts

Amplitude

Scattering

Quantum electrodynamics

Theoretical physics

Quantum mechanics

Formalism (music)

Observable

Classical mechanics

Journal of Physics A Mathematical and Theoretical

Scattering amplitudes have their origin in quantum field theory, but have wide-ranging applications extending to classical physics. We review a formalism to connect certain classical observables to scattering amplitudes. An advantage of this formalism is that it enables us to study implications of the double copy in classical gravity. We discuss examples of observables including the total change of a particle’s momentum, and the gravitational waveform, during a scattering encounter. The double copy also allows direct access to classical solutions in gravity. We review this classical double copy starting from its linearised level, where it originates in the double copy of three-point amplitudes. The classical double copy extends elegantly to exact solutions, making a connection between scattering amplitudes and the geometric formulation of general relativity.

The SAGEX review on scattering amplitudes Chapter 14: Classical gravity from scattering amplitudes