|MLA Citation:||Bloomfield, Louis A. "Question 1373"|
How Everything Works 18 Aug 2018. 18 Aug 2018 <http://howeverythingworks.org/print1.php?QNum=1373>.
The time slowing effect is acceleration—a person or clock that takes a fast trip around the earth and then returns to the starting point will experience slightly less time than a person or clock that remained at the starting point. This effect is a consequence of acceleration and the changing relationships between space and time that come with different velocities.
The time speeding effect is gravitational redshift—a person or clock that is farther from the earth's center experiences slightly more time than a person or clock that remains at the earth's surface. This effect is a consequence of the decreased potential energy that comes with being deeper in the earth's gravitational potential well.