How can Closed Timelike Curves be made?

[TheQuestionGuy14]

Hey. I really like the topic of Closed Timelike Curve's, they're an interesting subject matter, since they're allowed by certain field equations of GR. I was curious if there is any way (in the future?) we could warp spacetime to create a CTC, and maybe harness it? Could be useful.. ish. Thanks.

 

[Dale]

Most spacetimes that contain CTCs require matter with a negative energy density. We have never seen such matter, but if we ever did find some and if we could shape it into stable structures then we know what shapes they need