[Moderator's note: split off from another thread since this is a separate topic.] I am confused about closed timelike curves. To say that they are possible using an exact solution to the EFEs, like the Godel metric, and that they actually correspond to something in reality is where my confusion lies. What exactly does an exact solution to the EFEs tell us? Aren't they constrained by the distribution of matter density and observational facts? Does GR apply to what is possible outside of our spacetime? Secondly, personally, the idea of something creating itself seems absurd. It seems like logic itself would designate the term "self-creation" as analytically false. Am I missing something?