Carroll symmetry of plane gravitational waves
arXiv:1702.08284 · doi:10.1088/1361-6382/aa7f62
Abstract
The well-known 5-parameter isometry group of plane gravitational waves in $4$ dimensions is identified as Levy-Leblond's Carroll group in $2+1$ dimensions with no rotations. Our clue is that plane waves are Bargmann spaces into which Carroll manifolds can be embedded. We also comment on the scattering of light by a gravitational wave and calculate its electric permittivity considered as an impedance-matched metamaterial.
15 pages, 3 figures. To appear in Class. Quant. Grav