Relativistic time dilation does not explain why we cannot go back in time. The concept of time dilation, as described by the theory of relativity, is about the relative passage of time between different observers or reference frames. It addresses how time can be experienced differently depending on factors such as relative motion or gravitational fields.
However, time dilation does not provide a mechanism or explanation for time travel into the past. In fact, the theory of relativity, specifically the theory of special relativity, suggests that the speed of light is an absolute speed limit in the universe. It states that as an object with mass accelerates and approaches the speed of light, its relativistic mass increases, and it requires an infinite amount of energy to reach or exceed the speed of light.
This speed limit, along with other physical constraints and the causality principle (the idea that cause and effect must follow a specific temporal order), forms the basis for the notion that we cannot travel back in time. The laws of physics, as currently understood, do not provide a mechanism for traveling backward through time.
It's worth mentioning that there are various speculative theories and ideas, such as wormholes and the concept of closed timelike curves, that have been proposed in theoretical physics as potential pathways to time travel. However, these ideas are highly theoretical and have not been substantiated by empirical evidence or successfully incorporated into a consistent framework of physics.
Therefore, while time dilation is a real and observed phenomenon, it does not explain why we cannot travel back in time. The limitations on time travel are rooted in fundamental principles of physics and our current understanding of the universe.