2.b.5. The relativistic concept of time
Modern Physics with Albert Einstein’s Theory of Relativity –TR–provides an entirely different idea of time, being similar to neither objective nor subjective classical concepts of time. It is a definition derived from a mathematical axiom.
The current definition of a second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two megathin levels of the ground state of the isotope 133 of the cesium atom, in specific state and conditions. In addition, the definition of a meter is the distance that light travels in a vacuum during 1/299,792,458th of a second.
Consequently, the meter definition derives from the second if the duration of changes, the length of a meter must change to maintain the axiom of constant speed of light.
Just knowing that gravity and speed affect the “duration of the second,” by changing the palpitations of the Cesium atom, we realize the relativistic time is dependent on the very same current meaning of its unit, which dates back to 1967.
Time is relative due to the Theory of Special Relativity –SR– from 1905 and, subsequently, by the General Relativity –GR– of 1916. However, the latter affects time by establishing equivalence of gravity and acceleration, with the supposed temporal effects of motion in the SR.
Mathematically, SR expands and contracts time and space while General Relativity bends both by affecting the axis of the dimensions.
To summarize this section, the relativistic time detection, even in the atomic clocks, is due to a measurement error. However, it corresponds to an error in the very same definition of a second, adapted to the prevailing theory in 1967.
In other words, the cesian (from the cesium atom) definition of the second of 1967 produces nonabsolute time because the cesium is affected by changes in gravity and speed. Concerning fixed conditions of gravity and speed of an atomic clock, the TR would no longer be formally correct. Easy! Isn’t it?
Curiously, other conditions are set, such as temperature :)
Like the TR, the new concept comes fundamentally from the application of the mathematical formulas in the explanation about the failure of the anticipated goal of the MichelsonMorley experiment, specifically, the Lorentz equations.
In this experiment, according to its hypothetical premises, light travels unevenly through spaces in the same period. Because of the accepted axiom of the maximum and constant speed of light, the only alternative that remains is to make time relative.
This affirmation is a postulate of the Theory of Special Relativity; I suppose that, beforehand, it can conceal its clear concept of being an axiom. Indeed, its second postulate says, “The speed of light in open space has the same value for all of the observers, regardless of its state of movement.”
It is a contradiction in terms in which the idea “at the same time” and multiple “times” exists depending on the speed (space/time) of the observer (frame reference would be more explicit). We would say that each observer uses a different measurement of time, but it may be that we do not understand this theory very well or, what is the same, there is a single natural reference system.
Of course, with space happens the same thing as time, given that mathematically it is also necessary to maintain the axiom of the constant speed.
If there are any doubts about the relativity of space, they should resolve instantly reading the definition of a meter.
It is just as well that it only has two postulates and that at least something is constant!
Now then, there were other elements used by Einstein to establish the Special Theory of Relativity.
Among them, let us cite the following:

The Maxwell equations of electromagnetism, providing a more accurate calculation of the speed of light and pointing to a maximum speed of light

The Lorentz equations added mathematical complexity and declared that the speed of light was always the same or transformed in other cases.

The relativistic mass together with the massenergy transformation of the famous equation E = mc², which are real effects. The original formula is of Olinto de Pretto.

References to the subjectivity of time, such as the case of the lovers. Pure metaphysics!
Artificial examples or thought experiments about impossible situations, such as the twin paradox, a mirror clock in a spacecraft. Moreover, limits to simultaneousness by perception, such as the case of the train wagon.
Jumping ahead a little of the present confusion, we can say that the time and speed of a small ball or particle no only depend on the point of reference but also its movement. That is, a ball can travel with different temporal speed simultaneously. What an imagination!
In short, a fair number of bizarre things can occur, and they occur because of the excessive philosophical and mathematical influence.
From an objective point of view, as far as we know, not even one object has yet to travel in time nor suddenly appear or disappear due to having a distinct temporal speed. Moreover, already a branch of Quantum Mechanics postulates that photons are continually traveling back and forth in time, which is the Transactional Interpretation.
Relativity does not explain mechanisms affecting the atomic clocks in a spacecraft or their desynchronization with their brothers on Earth. Of course, it does not recognize that it is dealing with a measurement error.
Indeed, measurements of relativistic time coincide with mathematical predictions, but that does not take away the fact that, according to Modern Physics, the clocks alter by the art of magic. Pure metaphysics!
Interesting! A measurement error coincides with the theory. It is an ad hoc theory, which skips common sense and adjusts the philosophy of science with the Vienna Circle to be compatible with the scientific method.