Twin Paradox - a thought experiment by which try to "prove" the inconsistency of special relativity. According to the station, from the point of view of "stationary" observers all processes in moving object is slowing down. On the other hand, the principle of relativity declares equality of inertial reference frames. Based on this reasoning is based, leading to an apparent contradiction. For clarity, consider the story of two twin brothers. One of them (the traveler) goes to space flight, and the second (the stay-at-home) - is over. Most often, the "paradox" is stated as follows:
Formulation I. From the point of view of a moving clock homebody travelers have delayed the passage of time, so when you return, they have to keep up with the hours homebody. On the other hand, with respect to the traveler moving earth, so keep up to watch homebody. In fact, the brothers are equal, therefore, after the return of their watches to show the same time.
Explanation I. The brothers are not equal, as one of them (the traveler) had stages of accelerated motion, necessary for its return to Earth.