I missed something when I learned about Relativity. Everyone knows that story about twins. If one takes off in a rocket and travels near the speed of light, when he returns he won't have aged but his twin would be an old man. The part I don't understand is this: since there is no absolute reference frame why can't the twin in the rocket be considered to be standing still and the earth flying away at near the speed of light? That would make the twin on Earth the young one and the rocket guy aged.