Time might not be too hard to define (relativistic effects aside), but the problem is days and years. The reason for inserting and removing seconds is because t

Time might not be too hard to define (relativistic effects aside), but the problem is days and years. The reason for inserting and removing seconds is because the rotation of the earth is NOT static and precise. It changes so seconds are added and removed to keep the day from drifting. https://en.wikipedia.org/wiki/Day_length_fluctuations https://en.wikipedia.org/wiki/Day_length_fluctuations