These geometries can describe the universe and happen to be curved depending on wher mass in located. In this statement, the effects we associate with gravity can be seen to be equivalent with the effects of uniform acceleration of our reference frame. One sequence, however, must be explained by the General Theory of Relativity. At the train station MT sees a young man coming off the train meeting an old lady. It turns out the young man is the grandfather of the old lady.
Man spends a lot of time travelling where time moves more slowly.
Therefore he ages more slowly than people who live in town and do not travel much. Train engineer claims he is responsible for making people age more slowly on trains because he is brakeman. Suggests time slows down due to acceleration and decceleration. So young man nay be young due to effects of either Special or General Theory of Relativity. Twin Paradox The General Theory of Relativity also provides a more realistic explanation of the Twin Paradox.