FlockOfCats, 2 months ago

Here’s the current definition of a kilogram (tl;dr: it’s complicated).

And, for comparison, the previous one was just a carefully made hunk of metal that they handled very carefully

#metrology #science

Text explaining the definition of the kilogram (kg) as the SI unit of mass and a complicated formula
An image of the International Prototype of the Kilogram under multiple glass bell jars, a scientific artifact which defined the mass of one kilogram from 1889 to 2019.

futurebird, 2 months ago

@FlockOfCats

THREE bell jars!!

...

how is that better? Is it in some inert gas also?

I kinda like the hunk of metal, but the new definition isn't that bad.

FlockOfCats, 2 months ago

@futurebird

I know right? Three!

I imagine getting out the old kilogram must be like:

Scene from grinch where a nest series of platter with bell shaped lids are opened

PTR_K, 2 months ago

@futurebird @FlockOfCats

pippa, 2 months ago

@FlockOfCats i remember it making the news when they stopped using the physical weight! i mean, it was only in 2019 so it doesn’t require a massive amount of memory, but 😅

FlockOfCats, 2 months ago

@pippa true but I imagine the general response at the was like “oh new kilogram….cool?”

(I don’t mean to imply that most people are stupid so much as metrology is super niche and hardcore)

c0dec0dec0de, 2 months ago

@FlockOfCats not the Charismatic Science Nerd™️ quote I’m looking for, but this from Feynman on the topic of measurements is fun:
http://www.numericana.com/answer/feynman.htm
@pippa

FlockOfCats, 2 months ago

@c0dec0dec0de that is good. Thanks for sharing!

c0dec0dec0de, 2 months ago

@FlockOfCats a whole lecture:
https://www.feynmanlectures.caltech.edu/I_05.html
And still not containing the bit I’m looking for (something about measuring something common and not getting a truly accurate measure due to interference and thermal expansion).
@pippa

pippa, 2 months ago

@FlockOfCats i knew they were always super vigilant about keeping the kilogram weight super carefully so at the time i was just like, “oh this new way is much better, i wonder how the hell they came up with the formula, that has to have been crazy difficult, glad it wasn’t me” and that’s about it 😂

NormanDunbar, 2 months ago

@pippa @FlockOfCats First they started with the exact measurement for the kilogramme, then they , um, erm, ah, worked backwards? 😉

INCO, 2 months ago

@FlockOfCats However reasonable their arguments might have been, I'm still a little bit bummed they didn't adapt the
smooth silicon orb
proposal to redefine the kilogram... 😔

It would be so cool to have a tangible artifact again!

FlockOfCats, 2 months ago

@INCO now there’s an orb you can ponder!

zleap, 2 months ago

@FlockOfCats

Agreed, once you look more in to this, e.g definition of a unit then it is really interesting but takes quite a lot to comprehend.

I think we are now going to use Yittrium to define a second rather than Caesium.

tokyobybike, 2 months ago

@FlockOfCats Or we could just use the American system which is based on “this is a potato”.