According to our current understanding of physics, traveling at the speed of light does not allow you to go back in time.
The theory of relativity, proposed by Albert Einstein, states that as an object with mass accelerates and approaches the speed of light, its mass increases and it requires more and more energy to continue accelerating. The theory also predicts time dilation, where time appears to pass more slowly for objects in motion relative to a stationary observer.
As an object with mass approaches the speed of light, the energy required to accelerate it further becomes infinite. This means that it is impossible for an object with mass to reach or exceed the speed of light.
Moreover, time dilation effects occur when an object is moving relative to a stationary observer, but they do not allow for time travel in the conventional sense. While time dilation would cause time to appear to pass differently for a fast-moving object compared to a stationary observer, it does not enable traveling back in time or reversing cause and effect.
The concept of time travel is a topic that has been explored in science fiction, but it currently remains purely speculative and has no scientific basis within our current understanding of physics.