At the moment, based on what we know about the natural sciences and physics, time travel is not considered possible in reality. Some of the equations and principles in theoretical physics do not allow for true time travel with the current state of technology and science.
Here are some of the main physical reasons why time travel might not be feasible:
Theory of Relativity:Einstein's theory of relativity shows that time and space are interrelated, and that time is not a separate entity. The passage of time depends on the state of motion of the observer. At extreme speeds and gravitational fields, time is distorted, but this is not the same as traveling freely on the timeline.
The Law of Cause and Effect:The principle of causality in physics states that causality is irreversible. If time travel is possible, then causality can be violated, leading to paradoxes and logical contradictions.
Energy Requirements:Some theoretical concepts of time travel involve a lot of negative energy or peculiar physical structures such as wormholes. Our current understanding of these forms of energy is very limited, and it is unknown whether they exist or can exist stably.
Paradox Question:Time travel can lead to a series of paradoxes, such as the famous "grandfather paradox", which states that if you are able to travel back in time and influence your grandfather, then you have the potential to influence your own existence, triggering logical contradictions.
Overall, while time travel is a fascinating subject in science fiction literature and film, it is still considered impractical under current scientific understanding. Future scientific developments may bring new insights and possibilities, but so far, time travel has remained in the realm of science fiction.