Time dilation

he increase in the time between two events as measured by an observer who is outside of the reference frame in which the events take place. The effect occurs in both special and general relativity, and is quite pronounced for speeds approaching the speed of light, and in regions of high gravity. Time dilation needs to be accounted for when the speed is approximately

v > ½c.

After this the error in time becomes significant and increases rapidly if relativistic effects are not included.