According to the theory of relativity, time dilation occurs when an object moves relative to another object at speeds close to the speed of light. If you were to travel near the speed of light and then turn around and head back toward Earth, some interesting effects would occur.
From the perspective of an observer on Earth, time would appear to pass more slowly for you as you approach the speed of light. This phenomenon is known as time dilation. As your velocity increases, time would slow down for you relative to the stationary observer on Earth. This means that while only a certain amount of time would pass for you during your journey, a longer duration would have passed on Earth.
When you turn around and head back toward Earth, the situation becomes more complex. In the frame of reference of the observer on Earth, your velocity changes direction, and your time dilation effect would also change. As you decelerate and change direction, time dilation would cause time to appear to "catch up" with you. This means that from the perspective of the observer on Earth, the time that passed for you during your outward journey would seem to be condensed into a shorter duration during your return journey.
In summary, traveling at speeds close to the speed of light would result in time dilation effects, causing time to pass more slowly for you compared to observers on Earth. When you turn around and head back, time would appear to "catch up" with you, and the duration of your journey, as perceived by observers on Earth, would be shorter than the time experienced by you during the entire trip.
It's important to note that these effects become significant only at velocities close to the speed of light, and they have been experimentally verified in particle accelerators and through other means.