Hi! I'm new to the forum (although I've been reading posts for a while), so this is my first post. Anyway, I am studying electrical engineering and am taking my second semester of physics currently. I have been taught Special Relativity, and have a good grasp on the basic concepts. In all of the examples we used, and in all of the equations we learned, a constant velocity is assumed. I have been led to believe that acceleration must be answered using General Relativity -- which I really only have a very basic understanding of. My question is this: If, say, a space ship were traveling close to the speed of light, and then had to stop and turn around, how would time dilation be affected? I know that in Special Relativity, from the frame of an observer on Earth, time on the ship must slow down. How then, would a ship, on a round trip, be affected by time dilation? And how can those effects be explained? Now suppose the ship did not have to stop and turn around, but kept at its constant velocity and turned in a circular pattern. According to classical mechanics, the ship would then deal with an angular acceleration (right?). So then, how would time dilation affect the ship? I have a hunch that this all refers to the fact that the ship, in both cases, must accelerate (or decelerate) to change its direction, but I do not know what this means for time dilation. Thanks!