Editing Closed timelike curve (section)

== General relativity ==
CTCs appear in ''locally'' unobjectionable [[exact solutions in general relativity|exact solutions]] to the [[Einstein field equation]] of [[general relativity]], including some of the most important solutions.  These include:
*the [[Misner space]] (which is [[Minkowski space]] [[orbifold]]ed by a discrete boost)
*the [[Kerr metric|Kerr vacuum]] (which models a rotating uncharged [[black hole]])
*the interior of a rotating [[BTZ black hole]]
*the [[van Stockum dust]] (which models a cylindrically symmetric configuration of [[dust solution|dust]])
*the [[Gödel metric|Gödel lambda dust]] (which models a dust with a carefully chosen cosmological constant term)
*the [[Tipler cylinder]] (a cylindrically symmetric metric with CTCs)
*[[Bonnor-Steadman]] solutions describing laboratory situations such as two spinning balls
*[[J. Richard Gott]] has proposed a mechanism for creating CTCs using [[cosmic strings]].

Some of these examples are, like the Tipler cylinder, rather artificial, but the ''exterior'' part of the Kerr solution is thought to be in some sense generic, so it is rather unnerving to learn that its ''interior'' contains CTCs. Most physicists feel that CTCs in such solutions are artifacts.<ref name="kerrtube1">Roy Kerr (Crafoord Prize Symposium in Astronomy): ''[https://www.youtube.com/watch?v=LeLkmS3PZ5g&t=26m Spinning Black Holes]''. (YouTube, Timestamp 26m)</ref>