The speed of light in a vacuum, denoted by the symbol "c," is a fundamental constant in the universe. According to the theory of relativity, specifically Einstein's theory of special relativity, the speed of light in a vacuum is the maximum speed at which information or causal influence can propagate.
The theory of relativity also introduces the concept of spacetime, where space and time are intertwined into a four-dimensional framework. Within this framework, the theory establishes certain principles, such as the constancy of the speed of light in all inertial reference frames.
According to these principles, as an object with mass approaches the speed of light, its relative time dilation occurs, and its perception of time slows down compared to an observer at rest. However, light itself, which consists of massless particles called photons, always travels at the speed of light in a vacuum. From the perspective of a photon, no time passes, and it experiences no time dilation.
Therefore, while light travels at the speed of light, it does not "time travel" in the conventional sense because it exists in a frame of reference where time effectively stands still.