Complex Numbers

Weighty Matters

Science!

https://www.vox.com/science-and-health/2019/5/17/18627757/kilogram-redefined-wor...

Mostly I'm just linking this because it's interesting. Still, I have questions.

Big K [the official kilogram object] is not constant. It has lost around 50 micrograms (about the mass of an eyelash) since it was created. But, frustratingly, when Big K loses mass, it’s still exactly one kilogram, per the old definition.

Okay, but if Big K is the kilogram standard against which all other masses are compared, then how do they know it lost 50 micrograms? Anything you compare it to is, by definition, NOT the kg standard and so might also have changed mass through known or unknown processes.

Officially, in the US, 1 pound is defined as 0.45359237 kilograms.

Dafuq? A pound is a unit of weight. A kilogram is a unit of mass. Even in different places on the Earth's surface, with the level of precision we're talking about here, a kilogram might weigh more or less because the force of gravity changes slightly.

The new definition anchors the value of the kilogram to a constant in nature, which can never, ever change

Until we discover that it does.

Light speed, on the other hand, is unchanging.

Oversimplifying a bit. The speed of light in a vacuum is, as far as we have ever been able to tell, unchanging. But it's slower in air, water, glass, etc.

If you glossed over it all, here’s what all this change boils down to: We’ll no longer need a government — the US, France, whoever — or an international governing body to tell us what a kilogram is. It will be a fundamental truth of the universe, available to anyone with the proper equipment to realize it.

Regardless, that's pretty damn cool.

(I should note that my comments above are meant mostly humorously - the people whose job it is to set these standards are more knowledgeable and careful than I am. ...I hope.)