nicktallguy

I'm a non science graduate and trying to understand Einstein's theories as a beginner. In the relativity theory, as I understand it, if a person went on a trip to space in a rocket that travelled close to the speed of light, when they returned to earth they would appear younger in relation to any observers, who in turn would have aged more. But what I don't get, is that you could look at it as though the earth was moving away from the space traveller at the same speed (relative velocities) - so who is really moving away from whom, and why does the space traveller age slower and not the observers in earth ?