I know there are a few threds already on this subject, but it seems to me that all of them require preknowlage on the subject busides a wikipedia search wich only seems to tell you that If one twin leave earth vie. space ship, and travels .99c to a Galaxy 2 light years away, turns around, and comes back to earth, around 4 years will have gone by for that person. But because he was moving at the speed of light, time affected him differently, and back on earth, 13 years have gone by. Time is relative to speed, the faster you are going, the slower time is, the slower you are going, the faster time affects you. Speed is times medium, just like mass and tempter is sound and light’s medium. It would not be possible thought to change your ‘internal clock’ by driving 90 mph down a highway, because compared to the speed of light 90 mph is really quite insignificant. Or atlest thats what i got out of it. basicly what i want to know, and dont get, is WHY this happens, like what specifically is Earths time speed compaird to the speed of light? -wich seems to me would solve the question, though im not totally sure. What happens to Distance at near the speed of light, because there is an object in space going the speed of light, wouldnt it creat a 'curve' space? this might not seems so relevent, but if your going at the speed of light, wouldnt distance become not so relevent, or somthing like that...I dont really know anymore, ive staired at the problem for so long :yuck:. And i would also like to understand the effects of traveling near c on mass. would it become extreamly dence, or impload? uhh. Well if someone would be willing to explain this to me as soon as posible, in the simplest turms posible, I'm only in 9th grade, so i dont have much - if any deep understading of physics. -Thanks.