David Garfinkle

Oakland University, April 12, 12:00 pm

Gravitational wave memory and its electromagnetic analog

Gravitational waves stretch and squeeze space, but even when the wave has passed there is a residual stretch and squeeze known as gravitational wave memory. This memory is a consequence of the nonlinear Einstein field equations, but can be most easily understood by using linear perturbation theory. Furthermore this linear perturbative treatment is best understood by using manifestly gauge invariant variables: in this case the Weyl tensor. Gravitational perturbation theory using the Weyl tensor is analogous to Maxwell’s equations for electromagnetism. Correspondingly, there is an electromagnetic analog of gravitational wave memory called electromagnetic memory. I will present a proposal for how to measure electromagnetic memory.