[Serious] Is the Past Real?

[HappySkeptic]

I haven't worked through the details, but I have seen it claimed that causal loops can be created by toroidal black holes.

Now, whether such black holes can actually be made is another question.

The solution for causal loops in General Relativity involves a rotating universe.  Inside a fast rotating black hole, spacetime is rotating because of frame dragging, and perhaps such loops can exist.

A google search finds that if the rotation happens fast enough, and you get a naked singularity, you could traverse a causal loop outside an event horizon.  However, such black holes may be impossible.