So i finally got time to study it. I did not want just to run through as this topic is interesting to me. I personally believe (like that matters lol) that any interaction with the past would create a hard-fork (yes yes just like crypto) and they both continue their ways after a split. So basically you can not change the predestined future in a given universe but just crate an alternate reality that can be forked further. That might be the reason why we are never visited, or we are visited but such a visit results in a fork that we are unaware of. Theoretically number of states an atom can exist is limiteles until it is measured so scaling is not an issue here.

Another theory i have that time travel or recreation of past or modelling future might be possible. Recreation (travelling back the timeline) actually being easier due to collected data that can be traced. BUT. You can not change it since matter can not travel back in time or it will create a fork. But you can effectively see past and probably future without a chance to change or influence it. Knowing of a climate change and visible obvious facts does not have major change how people behave, does it? So if such a grand scale foreseeable fact does not influence our current behavior why do we need any detailed predictions. This second part is more philosophical one. The first one being very real and practical i believe :DDD