I am starting a new thread as my last one was unceremoniously hijacked by those who should know better and then closed by moderators when boundaries were crossed in the hijacked thread. I am not complaining as it was an interesting diversion, but now, if acceptable, I would like to return to the question of how this diagram, courtesy of 'Ebeb' from #124 in thread "Proper (and coordinate) times re the Twin paradox", works. For when I shave it with Ockham's Razor I see some significant differences Reducing the time frame to 1 second the facts are: after 1 second each light will have travelled 1 light second. measured by the observer with each clock, the light in their clock will have reached their mirror Relative to clock A, clock B will have travelled 0.6 light seconds, the light in B will have travelled 1 light second and will have reached point (0.6,0.8) The light in clock B arrives at the mirror in clock B after travelling 1 light second measured within clock B, yet, relative to clock A, it has travelled 1.25 light seconds taking 1.25 seconds to arrive at the mirror. Relative to clock A, the light has travelled the extra distance 0.6 light seconds along the x axis to point (0.6,0.8) and 0.75 light seconds with clock B (in clock A's frame) by the time it has reached the mirror. So between two fixed events; the generation of the light and the arrival at mirror B, we have two different times. 1 second within the resting light (B's frame) and 1.25 seconds with the moving light in A's frame. This is what I see as time dilation - just as the moving clocks distance travelled 0.75 light seconds is length contracted to 0.6 light seconds in the resting frames: that is clock A's resting frame and clock B's resting frame. The moving clock's time units are longer (dilated) so that measurement of the clock runs slower - each tick takes longer can only be equated to the clock running slower but there are still the same number of ticks counted for the resting clock. i.e. the clock still reads the same which ever frame it is measured in. Between the same two events the moving clock ticks slower and travels further for each tick - time dilation - yet ticks the same number of ticks - as shewn by the clock reading. Or to put it another way the moving clock travels further and measures more time.