I’m sorry for such a convoluted question, but this has been bothering me for some time now. While the title isn’t quite accurate, I couldn’t think of a better way to phrase it - feel free to edit if you can.
In sci-fi literature, (backwards) time travel tends to take one of two forms: either (1) one’s actions were already taken into account in the timeline, leading to the trope of someone trying to prevent something from happening but causes it to happen in the end (think Doctor Who); or (2) one can actually alter the past, leading to a branching timeline (think Back to the Future).
Does Judaism address whether either of these are accurate? That is, assuming time travel is possible, can one go back in time and alter the past?
The flip side of the coin, which might open some other possibilities for answers: if I somehow receive a message from the future, can I take measures to prevent it from happening, or will it automatically happen regardless of what I do?
The main question ends here. The following are some of my thoughts on potential proofs one way or another from methods we know to be true of predicting the future.
While astrology, kishuf, necromancy, and urim v’tumim all do this to some effect or another, there is a fundamental issue with all of them that prevents them from being proofs - namely, a large portion of the message is left up to interpretation, and thus any inaccuracies might be chalked up to user error. Take the example of Paroh’s message of Ra’ah (Shemos 10:10) - while one could argue that the symbol was overturned, one could just as easily argue that it was never intended to refer to murder, and Paroh misread the stars.
Nevuah, also, isn’t a good proof: a negative prophecy can be overturned, but perhaps it was just to scare the people and never was intended to be fulfilled at all. A positive prophecy might never be overturned, but that could be just because Hashem doesn’t lie - not that it fundamentally can’t be overturned, but that He chooses not to overturn it.
While different, yedi’ah versus bechirah is very heavily related.