The concept of time travel, including the ability to avoid altering the future, is often explored in science fiction and theoretical discussions. However, according to our current understanding of physics, time travel remains speculative, and there is no scientific consensus on how it would work or whether it is even possible.
That being said, some fictional works propose various mechanisms to address the issue of altering the future when traveling back in time. Here are a few concepts commonly found in science fiction:
Novikov's self-consistency principle: This principle, proposed by physicist Igor Dmitriyevich Novikov, suggests that any actions taken in the past must be consistent with the present and future. In other words, if you were to travel back in time, you would be unable to alter events because your actions would have already been accounted for in the timeline.
Multiverse theory: According to this theory, each decision or action creates a new branching universe or timeline. When you travel back in time, you would enter a different parallel universe, separate from the one you originated from. Thus, any changes you make would only affect that particular universe, not your own.
Fixed timeline: In this concept, the timeline is predetermined and unchangeable. When someone travels back in time, their actions were already a part of the historical events. Essentially, you cannot alter the past because your presence and actions were always meant to happen.
It's important to remember that these concepts are purely theoretical and do not have a basis in scientific evidence. Time travel remains a topic of speculation and debate among physicists and philosophers. Until more is understood about the nature of time and the possibility of time travel, we can only explore these ideas through works of fiction and theoretical conjecture.