Do experiments like 1971's Hafele & Keating show that SR relativistic effects of time dilation are not mere products of measuring symmetry? Does such an experiment show that for the jets it is their clock that has kinematic time dilation in relation to the other clock that 'remains' stationary'. I want to say no but I don't know completely why. is this just the ladder thought experiment all over again and an issue of simultaneity? I realize we can say that some object is time dilated greater than another object but is this merely a factor that's agreed upon and not an 'absolute' understanding of which frames is actually undergoing the greater time dilation due to their speed. if speed is relative to an IRF and there is no way to tell who is moving or who is stationary then it seems that the factor of time dilation doesn't ascribe time dilation to any one frame of the other. It seems to me that the only non-controversially non-symmetrical time dilation effect is the gravitational effect where two frames of reference or more can agree on who's clock is ticking faster or slower relative to some altitude on a mass. Is there reason to believe that time dilation and length contraction as treated in a non-gravitational deep space SR scenario could have effects such that between two or more frames of a reference an agreed upon ordered set of greater than less than time dilations and or length contractions can be obtained? Or even if its a periodic motion aka an orbital motion around a planet where a stationary clock and a meeting up clock on a plane whos clock ticks slower after a 'round trip' relative to a stationary clock, does this tell us anything interesting about frame dependent and symmetrical time dilation or off set why there is a difference in clock meet-up. Is the issue cashed out in terms of the angular velocity (gravitational acceleration or centrifugal effect though this makes no sense since gravity slows down clocks (or is it a lack of constant speed on the jet clocks part) that accounts for a difference in clock times.