According to the theory of special relativity, a person traveling at speeds close to the speed of light will experience time dilation. Time dilation means that time appears to pass more slowly for the person moving at high speed compared to an observer at rest. However, this does not mean that the person will become physically younger in the sense of aging backward.
Let's consider a scenario where a person travels away from Earth at an extremely high speed, close to the speed of light, and then turns around to come back. When they return to Earth, they will indeed find that less time has passed for them compared to the time that has passed for people on Earth (the stationary observers).
This effect is known as the "twin paradox," where one twin stays on Earth, and the other twin travels away at relativistic speeds and then returns. The traveling twin will be younger than the twin who remained on Earth when they are reunited.
However, it's essential to note that the traveling twin didn't experience any physical time travel or reverse aging. They merely experienced time passing more slowly relative to the observers on Earth due to their high velocity. They still aged during their journey, but their aging was "slowed down" compared to the observers on Earth.
In summary, traveling close to the speed of light can lead to time dilation, making the traveler experience less time compared to stationary observers. But it won't cause them to become physically younger or reverse aging.