I can't help it! Time travel to the past always introduces the possibility of paradoxes. I love learning about these possibilities and the physics and properties of spacetime. There's nothing in the math that technically doesn't allow for travel to the past, but there may be barriers that render it impossible. I just watched a couple of videos tackling the subject.
This last one is the most recent and the first time I think I'm able to wrap my head around how multiple universes can exist at the same time, right next to each other using QFT and wave mechanics to explain it.