Never do we change a completely imagined, clearly defined linear measure. We don't change the fahrenheit scale as we use temperature measurements. Humidity, radioactivity, velocity, weight- None of these are ever manipulated. I hope this helps to make a point. Why does it automatically make sense to alter the units of time at various speeds when these speeds are unattainable and thus only studied in theory? Universal simultaneity is completely simplistic, and couldn't cause problems in experimentation results. In fact, don't try to alter units of time if your profession is in forensics- you may be charged with aiding and abedding!
I have always pointed to the obvious arrogance of needing to compensate for a clock which is being affected by its environment, but changing units or theory instead. Throughout time we have strived to develop a more reliable, durable clock which would resist all exposures of its envivonment- ie. my water resistant watch. Are you really going to accept time is different in the oven because my clock in the the oven reads a different time than an identical one just outside the oven? No, of course not. We know at these levels it is the environment is too hot in my oven for the clock. At more fantastic levels, though, we easily beg to have differences in fundamentals. So, if we tavel at this speed use this ruler, but at these speeds use this other ruler. Somehow an oversight committee should put regulations on us to prevent changing measurement units. We never know what could happen if this sort of information fell into the wrong hands. If the wrong group of people made a tiny change to the units of a measure to fit their theory, then there could be catastrophic changes to Science-- wait, this has happened in Time.
I have never been told Einstein differentiated between time and one's perception of time, so is it too much of a crime to assume he blended or somehow confused the two? Because of course the two are not the same. For example, My coworker and I worked the same shift, so did we perceive time at the same rate?- well no. To me the day dragged on, and to him it was very quick. We know different work loads, anticipation of events planned after work, etc. all change one's perception of time. Time, of course, simultaneously went right on with the entire universe. So it seems to be impossible in a lot of ways for my coworker and I to figure out if time is constant.
Find the forces affecting your clock. Time is a fourth dimension, but it's units must be left unadulterated unless you want to open the door to altering all other units of measure. The x,y, and z axes all continue on infinitely, and exactly- so should Time. When we measure time, what is measured is the duration of a given event or force. My confusion is how brilliant physicists can be oblivious to the difference between Time and Perception of time.
Universal Simultaneity- prevent criminals and the ignorant from changing this!