Hi, I am reading the biography "Einstein's greatest mistake" from David Bodanis. On page 39 the author explains some of the consequences of relativity by referring to (although he doesn't mention it by name) the twin paradox. He explains that someone accelerating at high speed away from earth would see life on earth passing by very quickly, while someone on earth observing the man in the rocket would see him moving through time very slowly. However, I remember reading a popular science book by some or other physician that in both cases one observer would see the other in slow motion and that it is only when one of the two makes a U-turn to catch up with the other that they have had time passing at different rates when they meet up. Which is the correct interpretation?