Gravitational plane waves are described as "non-flat solutions of Albert Einstein’s empty spacetime field equation".
[1][2][3][4] They are a special class of a vacuum pp-wave spacetime.
In general relativity,[5] the may be defined in terms of Brinkmann coordinates by
can be any smooth functions; they control the waveform of the two possible polarization modes of gravitational radiation.
This relativity-related article is a stub.