Disseminating the New Kilogram: An International ‘Dry Run’
nist.gov
nist.gov
http://scitation.aip.org/content/aapt/journal/ajp/83/11/10.1...
(Open Access)
For that, NIST has a fundamental standard for the standard volt.[1] So the fundamental standards now are time (atomic clock), the speed of light in vacuum, and the standard volt. The meter is now defined in terms of the speed of light in vacuum and a time.
[1] https://www.nist.gov/news-events/news/2013/04/primary-voltag...
This is a tremendous benefit even if I am not required to make my mass measurements anywhere near the level of precision which NIST is capable of itself discerning. My target for precision is simply to be measurably better than the next best operator. NIST gives a final reference against which the quality of measurement can be correctly judged.
I have personally certified many billions of dollars worth of cargo in a way which is traceable to the NIST mass standard in particular, more so than most other single-handed individuals by far. Naturally, I started early which was an unfair advantage, but I recognized the need for traceability to a primary unquestionable standard, especially when I'm advancing the underlying measurement technologies in ways which are not being published or would be difficult for less experienced operators to grasp. From an extreme viewpoint, the only alternative would be to otherwise rely on superstition.
Turns out, without knowing it, I have spent years focused on avoiding the kind of difficulties that Theranos appears to be involed in, with their emerging testing technology in their field of analysis.
I prefer my results to be traceable to NIST before they emerge from the lab.
Insurance companies have always gotten a lot more upset over a slightly incorrect result in my field compared to the field of routine blood work.
youtube-dl 'https://cdnapisec.kaltura.com/html5/html5lib/v2.47/mwEmbedFrame.php/p/684682/uiconf_id/31013851/entry_id/0_gaag5ixq?wid=_684682&iframeembed=true&entry_id=0_gaag5ixq'
And that was the filesize I got. [info] Available formats for 0_gaag5ixq:
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So, you're both right.In the second Artemis Fowl book, there is a centaur who uses a human laptop (magical creatures live in a technologically advanced society underground), and the first thing he does is mute it. He complains that humans are unevolved and have some sort of compulsion to make their products emit sounds and and lights.
But, as the video went on, the sounds effects just go more and more ridiculous. An alarm sound as the object is sent down a tube?! And the coup de grace was the lawn mower sound effect at the very end as the object was wheeled away.
http://www.nature.com/news/kilogram-conflict-resolved-at-las...
Kilogram conflict resolved at last (2015)
The problem with this is it isn't even fragile, it's _not reproducible_. The worst part is that other SI units depend on the kilogram, so they all change as this drift occurs! After a certain amount of time, how will we know what a "real" kilogram is? See here for discussion of this SI problem: https://en.wikipedia.org/wiki/Kilogram#Dependency_of_the_SI_...
The point of the watt balance approach is to make it possible for a lab to reproduce the kilogram without another kilogram reference. That's what this is about, and I don't really think it's embarrassing. I think it's very, very hard.
If you tried to use water ice as a standard, you'd find that its mass was changing all the time as the ice sublimated away, or humidity condensed onto its surface. It would be impossible to make precise measurements.
How do you measure a known quantity of water to within a few tens of parts per billion? Do you specify the proportion of light to heavy water? (For 'normal' water about 1 in 41 million.) What about contaminants in the water? There are so many uncertainties that it's impossible for all practical purposes.
The whole point of using 'rare' silicon is that we already have commercial processes for producing ultrapure, defectless, monocrystals of the stuff (for use in computer chips), so it's easy to reuse that technology for defining a kilogram.
Are you aware of all the matter exchange processes that are continuously going on at the surface of water ice under normal conditions?