@RedTechEngineer >Go ahead and produce me a vacuum and measure how far light travels through it in 1/299792458th of a second.
Yes, that can be easily measured.

>Ah yes, the base unit "6.02214076×10^23", so glad that exists.
Yes, you know the exact value.

>Why is "kilogram" a base unit and not gram?
Convenience - you can make gram the base unit just fine.

>therefore a Second is defined as a function of a Second???
Based.