SR leans more toward direct observation rather than explanation, which is fine, mostly resulting from experiments with aberration and M-M type experiments, but I would like to know more about the how's and why's involved. I have come to some of my own conclusions, but will only ask questions leading toward my particular areas of interest to see what responses the members here will make, which should be very instructive. Q1) Why is the time dilation between frames for the ticks of a light clock the same as that of mechanical clocks, radioactive decay, vibrations of cesium atoms, etc? How are they related? Q2) Why do rods in an M-M type experiment in a moving frame contract in such a way that the result will be null? In other words, why is it so important to a body that light be transmitted isotropically that it must contract in order to do so? Why not just stay the same?