The Second and the metre are well defined. We have those units available. Of course units are meant to express measurement, tools to compare with precision, and interchange that information objectively. If we want a measure, we need a reference. Those are units for differences, but what about a coordinate system that let to a localization?
Spatial coordinates In space we can more or less easily know where we are, over Earth surface we can identify different landscapes, Earth Magnetic Field, the Sun, the far away stars, (and not to mention GPS).. We have found many ways to unambiguously locate for 3D. It would be imposible for us to "locate" if we couldn't differenciate one point from another. Measures depend on asymmetry.( perhaps existence depend on asymmetry ).
Time coordinate Seems easier, it's one coord instead of three.. Well.. it's really a bit harder, this coord has no so much asymmetry
How can we differenciate one point from another in time?
It's known that Carbon-14 dating is used on Earth to identify how old is something, This is to date in the present something found from the past. Although I think this is a great discovery in this matter, is not very precise, and it's accidentally, I mean, nobody planned to put C14 in a pyramid to date it..
Does we have a better dating system?
There is a way to date now something for the future?
It's known that Entropy is a time asymmetry but.. it's possible to leave precise traces to the future?
Perpahs we could construct an artifact with a known entropy and a known rate of change
Radioactivity decay is the most similar to that, but I've read about some evidence that rates are no constant.
It is even possible? I think it's a deep problem (even limiting it to Earth).
There are many "questions" included on this question, but all can be reduced to discuss the feasibility of a time coordinate system, and posibilities about this.
Thank you very much for reading