While non-relativistic time is the observable quantity measured (or approximated) by physical clocks, in general relativity clocks measure s along th… - Carlo Rovelli

If we want to understand the past we must do so on its own terms, and disregard the future of that past, but if we want to understand the present we better not disregard the past steps that were essential for getting to the present. This is of importance especially for those of us engaged in trying to push ahead the scientific path of discovery today. We are not much interested in what scientists did wrong, there is too much of that. We are interested in what they did right, because we are trying to copy them in this, not in that.

The notion of time familiar to us may... be reconstructed in special physical situations, or within an approximation, as... the "surface of a liquid" disappears ...[at] the atomic level, or "temperature" ...makes sense only in certain physical situations and when there are enough degrees of freedom.

Children grow up and discover that the world is not as it seemed within the four walls of their homes. Humankind as a whole does the same.