The way the twin paradox is explained, the twin on the ship ages slower than the twin on earth because he is moving at velocity with respect to the twin on earth. This makes sense from the twin on earth's reference frame, but wouldnt the twin on the ship see it the opposite. From his viewpoint, the twin on earth is aging slower? So from his viewpoint, he should be older than the twin on earth upon returning because the earth had been moving fast with respect to him. Maybe the example is always just stated from the twin on earth's perspective, but thats never explicitly stated. Sometimes it made to sounds like there is an absolute velocity in the universe and the twin on the ship IS moving fast with respect to the earth and not the other way around. I know this is not true, but could someone clarify? Thanks.