The absence of any recorded visits or interactions with future time travelers, despite the possibility of time travel, is often referred to as the "time travel paradox" or the "Fermi paradox of time travel." There are several speculative explanations for why we might not have observed any such visitors from the future:
Time travel is not invented or accessible in our future: It is possible that time travel is simply not achievable in our future, or it is so difficult or impractical that no civilization has successfully developed the technology. If time travel is not possible, then we wouldn't expect to encounter any future visitors.
Time travel is heavily regulated or restricted: If time travel were to exist, it might be subject to strict regulations or limitations to prevent interference with the timeline or to maintain the integrity of the past. Future civilizations might have policies in place that strictly prohibit or control interactions with the past, ensuring a minimal impact on the course of history.
Time travel is secretive or clandestine: Future time travelers, if they exist, might be intentionally hiding their presence or disguising themselves to avoid altering the timeline or to maintain the integrity of their mission. They may have reasons to remain hidden or not make themselves known to prevent any potential disruptions or paradoxes.
Time travel has unforeseen consequences or limitations: It is possible that time travel, if achieved, comes with unforeseen complications, risks, or limitations. These might prevent time travelers from freely interacting with specific periods or individuals in the past or future, making their presence undetectable or minimizing their impact on historical records.
We simply haven't encountered them yet: It is conceivable that if time travel is possible, we may not have reached a point in human history where future time travelers have chosen to visit or make their presence known. The absence of such encounters might be a matter of timing or coincidence.
It's important to note that these explanations are speculative and based on hypothetical scenarios. Since time travel remains purely theoretical at this point, the absence of recorded visits from the future does not provide definitive proof for or against its existence.