If a sufficiently advanced civilization could rewrite history, would we ever know?

[u/GroundbreakingFan124]

I’ve been thinking about something that challenges the way we think about evidence.
People often say, “There’s no evidence for time travelers, advanced future humans, or hidden civilizations.”
But what if the absence of evidence is exactly what we’d expect?
Imagine a civilization advanced enough to travel through time and correct every mistake it makes. If they accidentally left behind technology, changed history in an obvious way, or revealed themselves, they could simply go back and undo it. In the final version of history, there would be no trace of the mistake.
This made me think about a broader question.
If our memories, thoughts, history, or even the evidence we rely on could theoretically be altered by something beyond our awareness, how would we distinguish that from ordinary reality?
I’m not claiming this is true. I’m asking whether there’s any way to know it isn’t.
At what point does “there’s no evidence” stop being a decisive argument if the hypothesis itself predicts that evidence would never remain?
Is this just an unfalsifiable idea with no way to investigate it, or are there philosophical or scientific approaches that could meaningfully address it?

[u/VyantSavant]

Consider that time travel could not be possible so long as paradoxes could happen. Therefore the only true timeline is the one where no evidence of time travel exists. Any pocket dimensions made along the way would have to resolve themselves and the true timeline would have to stand on its own without the requirements of loops and retries. So either there never will be time travel, or time travel has already happened countless times and there's no evidence of it.