The Shrinking Kilogram

[Ben]

I found this article interesting. While the official kilogram sample is locked in a vault, "working standards" are used in its place. They have been shrinking due to handling. Reminds me of the story about the bird wearing the stone down:

High up in the north, in the land called Svithjod, there stands a rock. It is a hundred miles high and a hundred miles wide. Once every thousand years a little bird comes to this rock to sharpen its beak.

When the rock has thus been worn away, then a single day of eternity will have gone by.

https://www.scientificamerican.com/article/redefining-the-kilogram/

[griz]

My understanding is that gravity changes with altitude, latitude, and even with local geology.  Admittedly small amounts, but a lot more than the millionths of a percent they're talking about.  Could they be seeing permanent, slow, changes in average gravity?

[dogmush]

The kilogram is a measure of mass, and does not change with gravity.

If they are using scales to measure mass, they need to have corrected for local gravity.

[griz]

Whoops, I should have thought of that.  Thanks for the answer/correction.

[230RN]

I've noticed that shrinkage with groceries, too.

[freakazoid]

Recently watched a Veritasium video on them redefining it. Pretty interesting.
https://www.youtube.com/watch?v=Oo0jm1PPRuo

[Perd Hapley]