OK, do mathematical relationships in nature mean anything? If human analysis of natural physics is possible via mathematical symbolisms, does that suggest the mathematical nature of universal dynamical physics and therefore that positions/coordinates may not be properties of particles but they are very much properties of spacetime.

"OK, do mathematical relationships in nature mean anything?"

[Yes, but we don't know what. Human concepts/relations within the language of mathematics have the their meaning by definition. We don't know the fundamental concepts (if there is such a thing) that determine the structure and behavior of the universe. We use models, forms of representation. A 'timeline' on a spacetime graphic

represents (without all the irrelevant detail) a moving object (more like shorthand).]

[If we analyze the natural processes accurately, form a corresponding model with a good translation of the relations into a mathematical format, and record results that match predictions, the most we can claim is accurate measurements. It doesn't mean the universe behaves like the model. It's the other way around.

Are you using successful prediction to impose the same human methodology onto the inanimate universe?

Spacetime is just a term to indicate the interdependency of space and time. Especially when measurements are recorded as temporal intervals of light motion. Minkowski restored 'time' as a measure of distance/motion by replacing 't' with 'ct'. Units of measure are by definition. A randomly selected stick could be defined as a um, and labeled 'stick'. If an international science org. accepted it, then we would measure distances in 'sticks'. It has no meaning beyond its intended purpose. It is not a property of spacetime or the ether, etc. It is a convention, just as coordinates and clocks.]

[On my favorite quotes list:Henri Poincare, The Measure of Time, 1898

"We do not have a direct intuition for simultaneity, just as little as for the equality of two periods. If we believe to have this intuition, it is an illusion. We helped ourselves with certain rules, which we usually use without giving us account over it [...] We choose these rules therefore, not because they are true, but because they are the most convenient, and we could summarize them while saying: "The simultaneity of two events, or the order of their succession, the equality of two durations, are to be so defined that the enunciation of the natural laws may be as simple as possible. In other words, all these rules, all these definitions are only the fruit of an unconscious opportunism."]