[Serious] Is the Past Real?

[polymath257]

If one could, even hypothetically, travel back to the past, then, the past must be real:

EarthSky -- Black holes are time machines, with a catch

Also seems to argue for the Many Worlds interpretation of Quantum Mechanics.

Causal loops are compatible with General Relativity, but I'm unaware of how they would generated in a Black Hole.  This article gives no reference to any theory.

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.