According to our current understanding of physics, an object with mass cannot travel at the speed of light. As an object with mass approaches the speed of light, its energy requirement to accelerate further increases, and its mass appears to increase as well. Therefore, reaching or exceeding the speed of light would require an infinite amount of energy, which is currently not feasible.
However, the concept of time dilation in special relativity suggests that as an object approaches the speed of light relative to an observer, time appears to pass more slowly for that object compared to the observer. This means that from the perspective of the moving object, time is passing at a "normal" rate, but for the observer, time appears to be passing slower for the moving object.
This phenomenon has been experimentally verified and is an important aspect of Einstein's theory of relativity. However, it's important to note that even at speeds close to the speed of light, time dilation effects are relatively small and would not allow for significant time travel into the future or past.
The idea of traveling through time, such as backward time travel or traveling faster than the speed of light, is still a topic of scientific speculation and remains purely theoretical at this point. There are various theories and hypotheses within the realm of theoretical physics, such as wormholes and certain solutions of general relativity, that suggest the possibility of time travel. However, these concepts are highly speculative and not currently supported by empirical evidence.