Traveling at or near the speed of light poses numerous challenges for the human body, and it is currently beyond our technological capabilities to achieve such speeds. However, if we were to speculate about the hypothetical scenario of a human body traveling at a significant fraction of the speed of light, there would be several factors to consider.
One major challenge is the enormous amount of energy required to accelerate a massive object, such as a human body, to relativistic speeds. The closer an object approaches the speed of light, the more energy is required to accelerate it further. Overcoming this energy barrier is currently beyond our capabilities and would likely involve technological advancements far beyond our current understanding.
Assuming we could overcome the energy challenge, there are several physiological and biological implications to consider. One significant issue is time dilation, a consequence of Einstein's theory of relativity. As an object approaches the speed of light, time slows down relative to an observer at rest. This means that while the traveler experiences a shorter passage of time, the rest of the universe would age significantly. Returning from such a journey could result in a substantial time difference between the traveler and the rest of the world.
The high velocities involved in relativistic travel would also lead to a phenomenon called relativistic length contraction. Objects in motion appear to shorten along the direction of their motion from the perspective of an observer at rest. This contraction could affect the functioning of the human body and potentially lead to physiological complications.
Additionally, traveling at such high speeds would expose the human body to intense radiation. Interactions with cosmic rays and other high-energy particles would be significantly amplified, leading to potential DNA damage and an increased risk of cancer and other health issues.
In summary, while it's impossible to say definitively whether a human body could survive partial light-speed travel due to the theoretical and technological constraints involved, the challenges posed by energy requirements, time dilation, length contraction, and radiation exposure would present significant obstacles.