Hi, before I question let me say I'm new both to this site and Physics in general, as such please forgive any ignorance on my part. I was given an example of time difference in regards to a 'my twin traveling at near the speed of light' scenario and I'm having trouble reconciling some of the logic. In the example my twin leaves earth traveling at .8c the twin travels 12.5 years out, turns around and returns. For me, from the earth frame or reference 25 years has passed. For my twin 15 years has passed (from the ships frame of reference). I'm fine up to this point. Where I start falling short is the explanation as to why this is. I was told that it's because Special Relativity requires consistent movement and my twin has had to turn around, therefor no Special Relativity. This doesn't make sense to me in as much as raises the question, "If I send my twin on a circular course, where the arc of that course will take 25 years at .8c (from the earth frame of reference) to loop back to it's origin point. Wouldn't the same thing happen?". In this case isn't it still 15 years from my twins frame of reference, though the aspect of turn around and return has been eliminated? In essence instead of a "out and back" my twin is being sent on a continual curve, under which Special Relativity would still apply.