Editing Pp-wave spacetime (section)

==Examples==
There are many noteworthy ''explicit'' examples of pp-waves.
("Explicit" means that the metric functions can be written down in terms of [[elementary functions]] or perhaps well-known [[special functions]] such as [[Mathieu function]]s.)

Explicit examples of ''axisymmetric pp-waves'' include

*The [[Aichelburg–Sexl ultraboost]] is an [[impulsive plane wave]] which models the physical experience of an observer who whizzes by a [[Schwarzschild metric|spherically symmetric gravitating object]] at nearly the speed of light,
*The [[Bonnor beam]] is an axisymmetric plane wave which models the gravitational field of an infinitely long beam of incoherent electromagnetic radiation.

Explicit examples of ''plane wave spacetimes'' include

* exact [[monochromatic gravitational plane wave]] and [[monochromatic electromagnetic plane wave]] solutions, which generalize solutions which are well-known from [[weak-field theory|weak-field approximation]],
* exact solutions of the [[gravitational]] field of a [[Weyl fermion]],
* the [[Schwarzschild generating plane wave]], a gravitational plane wave which, should it collide head-on with a twin, will produce in the ''interaction zone'' of the resulting [[colliding plane waves|colliding plane wave]] solution a region which is [[locally isometric]] to part of the ''interior'' of a [[Schwarzschild metric|Schwarzschild black hole]], thereby permitting a classical peek at the local geometry ''inside'' the [[event horizon]],
* the [[uniform electromagnetic plane wave]]; this spacetime is foliated by spacelike hyperslices which are isometric to <math>S^3</math>,
* the [[wave of death]] is a gravitational plane wave exhibiting a ''strong nonscalar null [[Gravitational singularity#Curvature|curvature singularity]]'', which propagates through an initially flat spacetime, progressively destroying the universe,
* [[homogeneous plane waves]], or ''SG11 plane waves'' (type 11 in the Sippel and Gönner symmetry classification), which exhibit a ''weak nonscalar null curvature singularity'' and which arise as the [[Penrose limit]]s of an appropriate [[null geodesic]] approaching the curvature singularity which is present in many physically important solutions, including the [[Schwarzschild metric|Schwarzschild black holes]] and [[Friedmann–Lemaître–Robertson–Walker|FRW cosmological models]].