Le Grand K comes to an end. New kilogram based on Planck's constant starts today

[gary]

For 130 years a hunk of platinum/iridium alloy stored in a subterranean
vault in Paris known as "Le Grand K" has served as the SI prototype unit for the kg.

With dust contaminants and polishing its weight would change by
micrograms over time.

Starting today and after years of planning, Le Grand K's use as the prototype
of the kg has come to an end and in its place a kg now is defined in terms
of Planck's constant.

This also has the advantage that it can be reproduced in labs around
the world.

Originally the kilogram was defined as the mass of 10 cubic centimeters of water at 4 degrees Celsius.

Story here :-
https://phys.org/news/2019-05-adieu-le-grand-kilogram-redefined.html

[Shark6]

:thumbsup:

[multiweb]

Le grand K will end up at an auction then make its way as a door stop or paper press.

[bojan]

All that platinum and iridium? Probably not... in someone's private collection is more likely.. or museum.

[gary]

Hi Marc,

I once had a brief conversation with a stranger in Paris.

He was a U.S. serviceman who was stationed somewhere in Europe.

He confessed to me he had licked a Monet.

I asked, "Why?"

He said he was in a gallery standing in front of this painting.
He got closer to examine the texture of the paint.
Then a bit closer and a bit closer and soon right up to the canvas.
He said he then felt this irresistible urge to lick it.
He said, "I looked around, saw nobody was watching, poked out my tongue
and just licked it".

After years of handling Le Grand K with silk gloves, I wonder if the
curator might feel a similar urge? :shrug:

[multiweb]

:lol: You meet some weird people in museums.