Hey guys, this is my first post. I posted here a few time a while ago, but forgot my logins :) I am no physics expert, just really enjoy learning about it when I can. Ok, what I need help understanding is the theory that for example if I leave earth travelling at the speed of light, and I travel for a peroid of time, lets say a year, when I come back to earth, people will not be 1 year older, but 30 or so. Now first, is that true? Can someone explain this to me? Thanks, hope its not a stupid question. Thanks very much!