Bear with me. I am a lawyer, not a physicist.... I understand how the light clock demonstrates time dilation with special relativity. I think I understand length contraction. Here is my question: at relativistic speeds, why does length contraction not affect the distance traveled by the light flash? In other words, why isn't the "V" shape of the light (as seen by the external observer) "squashed" and made more narrow by length contraction, thereby affecting the calculation of the distance traveled by the light etc.? Is it because the external observer would measure the distance using a meter stick on the frame of reference traveling at relativistic speed (which would likewise be contracted) or does the external observer use his own external meter stick that is not contracted? Thanks!!