1. The problem statement, all variables and given/known data Two twins start their clocks at the same time, one of them travels for 7 years at a speed of 4/5c, reverses direction and returns at half the speed. The other twin remains stationary, what is the difference in their age? 2. Relevant equations t = t_p γ 3. The attempt at a solution I'm hung up on the thought... when he reverses direction he travels at half speed. Intuitively I think that it takes him 14 years to return at half speed... but is this necessarily the case? How can I prove that it is necessarily 14 years for him to return (considering Lorentz contraction) or find the actual time it would take him to return?