According to our current understanding of physics, it is not possible for an object with mass, such as a human or any macroscopic object, to travel at the speed of light. The theory of relativity, specifically special relativity, states that as an object with mass approaches the speed of light, its mass would effectively become infinite, requiring an infinite amount of energy to continue accelerating. Therefore, it is not feasible for an object with mass to reach or exceed the speed of light.
However, let's consider a hypothetical scenario where an object with mass could travel at the speed of light. In this scenario, if the object were moving at the speed of light and encountered an object moving faster than it, a few things would occur:
Time Dilation: Special relativity predicts that time slows down for objects traveling close to the speed of light relative to a stationary observer. As a result, if you were traveling at the speed of light, time would effectively stop for you. This means that you would not experience the passage of time and, therefore, would not see any changes or events happening around you.
Photon Interaction: As an object traveling at the speed of light, you would be moving at the same speed as photons (particles of light). According to our current understanding, photons do not experience time, so they would not "see" or perceive anything. Therefore, from the perspective of a photon, there would be no concept of darkness or light.
Relativistic Effects: When two objects are moving at high velocities relative to each other, relativistic effects come into play. These effects can cause the light emitted by one object to be blueshifted or redshifted when observed from the other object, depending on their relative motion. This could alter the perceived color of the light, but it does not necessarily imply darkness.
It's important to note that this hypothetical scenario of an object with mass traveling at the speed of light goes against our current understanding of physics. According to the theory of relativity, as an object with mass accelerates towards the speed of light, its energy and momentum increase without bound, making it impossible to reach or exceed the speed of light.