When the argument in the previous post "Who Has A Longer Penis?" dated 21 Nov 2017 is applied to time duration, then to a travelling observer at high speed, any movements on an object at rest is in slow motion; to a observer at rest, any movements on a travelling object is quicken up.
That does not mean that the travelling object age faster. One second at rest, is longer while travelling when measured by the observer at rest. It is the same one second as experienced by the traveler. Both the traveler and rest observed experience the same time speed.
Gravity changes time speed. Free motion under the effect of a gravitational field, changes time speed.
A travelling person on the surface of earth age the same as when the person is at rest, even if it is at light speed, because gravity is the same and so their time speed is the same. (post "Time, Time Speed, Aging" dated 24 Apr 2014). GPS time is adjusted because of the difference in gravity the satellite experiences, which is related to its orbital speed because of its circular motion around earth. GPS experiences a different time speed not directly because of its orbital speed.
Under the action of a gravitational field without propulsion, acceleration to light speed means time stand still.
But the scaling factor \(c\) is arbitrary. Lorentz transform does not proof the light speed limit but applies the light speed limit, \(c\).
Have a nice day.
