The concept of traveling through another dimension and changing the past is often explored in science fiction, but it's important to understand the distinction between scientific theories and speculative ideas.
In our current understanding of physics, there is no direct evidence or widely accepted theory that supports the existence of dimensions that would allow for time travel or altering the past. However, there are theoretical frameworks, such as certain interpretations of quantum mechanics or theories involving wormholes, that propose the possibility of time travel. These theories, however, remain highly speculative and far from being experimentally confirmed.
Regarding the existence of multiple realities, there are various interpretations within physics, such as the Many-Worlds Interpretation of quantum mechanics. According to this interpretation, every possible outcome of a quantum event actually occurs in separate branches of reality, resulting in a multitude of parallel universes. However, it's important to note that these interpretations are still debated among physicists and have not been definitively proven.
In summary, while the idea of traveling through dimensions and changing the past is fascinating and widely explored in fiction, it remains speculative and outside the realm of our current scientific understanding. Our understanding of dimensions, time, and the nature of reality is still evolving, and further research and discoveries are needed to gain deeper insights into these concepts.