Definition of kilogram set to change to physical constant

[gary]

In an article in today's Sydney Morning Herald (http://www.smh.com.au/technology/sci-tech/the-kilogram-prototype-in-france-has-been-losing-weight-so-its-time-for-a-new-definition-20151016-gkbg9s.html), Marcus Storm reports that
at the 104th meeting of the International Committee for Weights and
Measurements (CIPM), which was held last week in Paris, that they
were satisfied after years of experiment that they found a new
method to define the kilogram.





Article here -
http://www.smh.com.au/technology/sci-tech/the-kilogram-prototype-in-france-has-been-losing-weight-so-its-time-for-a-new-definition-20151016-gkbg9s.html

[Eratosthenes]

This Perfect Silicon Sphere is the Most Precise Kilogram Ever

http://motherboard.vice.com/read/this-perfect-silicon-sphere-is-the-most-precise-kilogram-ever-

Scientists look to define kilogram with a super-round silicon sphere

http://ceramics.org/ceramic-tech-today/scientists-look-to-define-kilogram-with-a-super-round-silicon-sphere

[Eden]

Now all that remains is for the U.S. (Outside of NASA) to finally make the transition to the Metric system.

[Eratosthenes]

...don't forget the great nations of Liberia and Myanmar

the USA isnt alone on this front.

You may very well owe the USA, its people and administration a written apology

:D

[SimmoW]

Does this mean I can go down a size in my jeans? :-)

[leon]

With the discovery of this what is really going to change, :shrug:v and does it really matter. :question:
Surely time spent on this type of research could be better spent.

Leon :thumbsup:

[speach]

you must remember that the SI system is a socialist plot to over throw the great us of a!!!!:rofl:

[Steffen]

Well, I'll be sure to let my butcher know ;)

Seriously though, I'd love to know why exactly the reference kilogram bars can go "out of sync" by 60µg, especially since they are presumably made of the same material and kept under similar conditions?

[Kunama]

I'm going to try lose lose a few silicon spheres by Christmas......

[FlashDrive]

:rofl:

[gary]

This 2012 presentation (http://www.bipm.org/ws/CCM/MeP_2012/Allowed/November_2012/12a_6.1_BIPMMassCalibrations_WS_21n ov_final.pdf) by the Bureau International des Poids et Mesures
describes the process by which the prototypes are manufactured and
how they are washed and cleaned and then calibrated.

The platinum-iridium mass standards are cleaned with chamois leather
soaked for 48 hours in a mixture of equal parts ethanol and ether after
which the absorbed solvent is wrung out of the leather.

They are then steam cleaned with water.

Cleaning the prototypes can remove between 5ug and 60ug of "contamination"
depending upon when they were last cleaned.

http://www.bipm.org/ws/CCM/MeP_2012/Allowed/November_2012/12a_6.1_BIPMMassCalibrations_WS_21n ov_final.pdf

[mjfitzhenry]

It really is ridiculous that the fundamental unit of mass is defined by some random chunk of metal held in Paris. It's about time they based it on some physical constant like the rest of the fundamental units are.

[Steffen]

I wonder whether the alloy can absorb gases. Palladium, for example, which is in the same group of the periodic table as platinum, can absorb 900x its volume of hydrogen.

[KenGee]

Leon whats going to change is the kg. If we keep our current system then we will have to adjust all calibrated scales. They are effectively trying to move away from weights and measures being a relative scale to being an absolute scale.
For example time is a absolute scale now the second is defined as

"the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom ".

it used to be based on the mean solar day that varies through out the year by about 30 seconds.