According to our current understanding of physics, it is not possible for an object with mass, such as a human, to travel at the speed of light. The theory of relativity, proposed by Albert Einstein, states that as an object with mass accelerates towards the speed of light, its relativistic mass increases infinitely and would require an infinite amount of energy to reach or exceed the speed of light.
However, let's consider a hypothetical scenario where an object could travel at the speed of light. In that case, the concept of time dilation comes into play. According to special relativity, time dilation occurs as an object approaches the speed of light relative to an observer. Time would appear to slow down for the moving object compared to a stationary observer.
If we imagine a person traveling at the speed of light, their perception of time would be significantly different from an observer at rest. However, from the perspective of the person traveling at the speed of light, time would appear to be standing still, and they would not experience any sense of the passage of time.
In this hypothetical scenario, if the person could somehow turn around and look back, they would not see their "past self" because their perception of time would have effectively stopped. It would be impossible to observe events occurring after they started traveling at the speed of light because time would not pass for them.
It's important to note that this hypothetical scenario is purely a thought experiment, as no object with mass can actually reach or exceed the speed of light.