The theory you are referring to is Albert Einstein's theory of relativity, specifically the theory of general relativity. While general relativity does not explicitly provide a method for time travel, it introduces concepts that could allow for the theoretical possibility of time travel, at least according to some interpretations.
One of the key elements of general relativity is the idea that spacetime is a unified fabric, and the presence of mass and energy can cause it to curve or warp. This curvature affects the motion of objects, including the flow of time itself. In regions of intense gravitational fields, such as near massive objects or in the vicinity of black holes, time can be significantly distorted compared to a less massive or non-gravitational environment.
The concept of time dilation arises from the theory of relativity, which suggests that time can pass differently for observers in different gravitational fields or relative velocities. This means that if one were to travel near a massive object or move at extremely high speeds, they could experience time passing at a different rate compared to someone in a different reference frame. This effect is experimentally validated and has been observed in various experiments, including with atomic clocks.
While this time dilation effect does not offer a straightforward mechanism for traveling back in time, it does provide a theoretical foundation for the possibility of time travel in certain scenarios. Theoretical physicists have explored concepts like "time loops" or "wormholes" that, if they were to exist, might allow for traversable paths through spacetime, potentially enabling travel to the past or future. However, it is important to note that such concepts remain speculative and highly hypothetical, and no empirical evidence or practical implementation of time travel currently exists.