Not, like, “the kilogram” as in the unit of weight. But rather The Kilogram, i.e the physical object on which that unit is based.
Incidentally, Americans, the fact that metric units are based on internationally standardized and scientifically determined physical objects is the reason the rest of the world—and everyone in STEM fields—uses it instead of the Imperial system.1 Even Celsius falls under this, since a single “degree” in Celsius represents the same difference in temperature as a single degree in Kelvin—as opposed to a single degree in Fahrenheit, which is its own thing—just with the number labels jiggled around to make it more comprehensible to humans (an average “nice warm day” is approaching 300K).
The more you know, etc.
- It’s actually not even that: the US “Imperial” system is actually its own system that’s both, a) different to the original English Imperial system, and b) is used by literally no one else in the world. Oh, and it’s defined based on overly complex conversion formulae from SI units anyway. Go figure. ^