There is really nothing scientific about time as we mortals use it.
As soon as you bind the definition of time to the rotation of the earth, all bets are off about being "scientific".
A day has x hours.
An hour has y minutes.
A minute has z seconds.
Therefore, you have now defined a second as 1 / (x times y times z)
What happens when the earth speeds up by a fraction of a second?
Does the definition of a second change?
We can't define time with a day has x hours, an hour has y minutes, and a minute has z seconds.
If we define time outside of the rotation of the earth, metric is meaningless. We should be able to adjust. Let's say earth sped up. We should be able to say a day has more seconds now.
My guess is you define a second as the following?
A more precise definition of a second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
Ok that's good. In practice, we aren't very scientific. It will matter whether a minute has 60 seconds or 61 seconds or 100 seconds. I'm guessing we will have bigger problems if earth rotation spend up or slowed down considerably anyway.
There is really nothing scientific about time as we mortals use it.
As soon as you bind the definition of time to the rotation of the earth, all bets are off about being "scientific".
A day has x hours. An hour has y minutes. A minute has z seconds.
Therefore, you have now defined a second as 1 / (x times y times z) What happens when the earth speeds up by a fraction of a second? Does the definition of a second change?