Twin paradox
Each observer in the theory of relativity in all the time with its own measure,which would lead to the so-called twin paradox.Twins in one of space travel,its speed sailing close to the speed of light,and his brother to stay on Earth.Because of his campaign from the ground on the twins,the spacecraft on the passage of time more slowly.In this space will be found to return to his brother more than his aging.Although this seems to conflict and common sense,a series of experiments have proven that this scene of the twins travel some more young.