it seems to me that time dilation takes effect in the process of acceleration- similar to the affect of gravity on time- rather than in the kinetic energy of a constant velocity. 1- consider two ships departing earth in opposite directions at 200,000 km/hr each. an earthling sees the ships' clocks run slower, but the ships don't even see each other at all- since their combined separation speed is faster than the speed of light. are they aging backward relative to one another? that is absurd. 2- consider galaxies that are moving away from earth at near the speed of light. are their stars aging more slowly than the milky way's stars? that is equally absurd. time dilation must occur in the process of acceleration.