Atlan0101, the two reference sources I cited in post #4 show some real differences emerge between Newtonian physics and Relativity, especially when it comes to determining length, mass, time, kinetic energy. Are you suggesting that neither model of physics can be tested and supported today in your post #5?
Rod, you are still talking one reference frame rather than two.
Just ONE! Can't you see that?! There is an unobservable universe out there and relativity breaks down between it and the observable. The observable is always behind the unobservable regarding time. Always! And the more distance expands the more time apparently slows (light taking longer to cross distance, including changes in velocities, in momentum) and falls into history versus the local observer, the more uncertainty accelerates and becomes the rule. You didn't even start to include gravity (gravities) as a factor. You're math stated there was nothing between observed and observer. Nothing whatsoever. Light instantaneously went from event to detection by the observer, according to the math picture. Instantaneously!, Rod. In the picture you drew with the math, there was no time at all for the unobservable real time traveler and clock in their boxed four-dimensionality to gain on the mathematical picture the observer draws from observation
of the observable universe existing only within an observation. Sure it works for the LHC, a confined universe within the observer's universe. The same with the traveler's drive within his spaceship, but that isn't the opening space-time universe the traveler is traveling, the space-time the traveler will manage to contract with his own constant of acceleration through it.
And I mean
SPACE-TIME, not just time. An elastic bubble of space-time environment was not what you were dealing in for the traveler. You were dealing in the observer's sense of space-time environment from the observer's sitting room. Your measurement of space-time environment for the traveler was exactly the same as the observer's measurement of space-time environment for himself
on Earth. The difference then became the clocked difference and age difference, exactly what would be observed concerning the traveler in the light speed picture arrived to the observer sometime after the fact of an event, and the clocked time of the event, there and
then! A history, Rod. The clocks would not show any parallel, any simultaneity, of universe.
Rod, Newtonian and Relativity physics both deal in local universe, the lone, single, reference frame common to both observer and traveler individually, but not common between them. Not in the non-locality become the fact between two divided, and dividing, local universes that no longer have either's relativity
between them. That now have only Quantum Mechanics' principle of growing uncertainty between them. Each universe being unobservable to the other. Neither Newton nor Einstein dealt in the unobservable universe. Well, Einstein tried later in life and failed miserably because there was no such concept as 'Multiverse' in his time.
Rod, your math is correct, I suppose, but only for the clocks and events in the light. Correct only for the relative, the histories, not the un-observably simultaneously current and real that are not, and will not be, anything like quantumly entangled with each other to serve the math. Your map is not anything like the territories you think your mapping.
There are even physicists now who increasingly no longer trust that picture you cited and drew for divided four dimensionalities. Who are beginning to realize that they are divided universes, each with the same physics, but not between them. That you don't simply raise up their common local dimensionality to encompass that larger environmental dimensionality.