> a cylinder of a platinum alloy stored at the BIPM in France, will now be retired. It will be replaced by the Planck constant – the fundamental constant of quantum physics.
I thought they did that long time ago.
I thought they did that long time ago.
It seems that they settled on this definition because a Kibble balance[1] has shown to be precise and practical enough:
> Accuracy criteria were agreed upon in 2013 by the General Conference on Weights and Measures (CGPM) for replacing the current definition of the kilogram [...] with one based on the use of a Kibble balance. These criteria have since been met, and the definition of the kilogram and several other units will change on May 20, 2019, World Metrology Day, which celebrates the establishment of the SI, or metric system, in 1875, following the final vote by the CGPM on November 16, 2018.
I recently ordered a picture frame from Amazon. It came in its packaging box, which was placed in a box by the manufacturer. That box was put in another box by Amazon and shrink wrapped to a large piece of cardboard, which was then put inside yet another box.
On the surface, it seems crazy, but Amazon did manage to get it to me undamaged.
I do happen to have the previous generation time standard in my garage, though, a HP 5061A Cs clock.
They are. They are made identically to the primary.
Fingers crossed. :)
Are other units still tied to physical measures, or is this all of them?
As you stroll Paris, you can still find various meter secondary standards - bolted onto public buildings to aid in commerce back in the day.