Tuesday, April 26, 2005

 

The French get slammed again

French supremacy with regards to the international definition of the kilogram may be coming to an end. Currently, the plum-sized platinum-iridium standard is stored in Paris. If some scientists have their way, the kilogram will be redefined in terms of some obscure physics mumbo jumbo.

The take-home point is that Americans will no longer have to come to France and brave the legendary snootiness and sense of self-importance of the parisians to have their scales calibrated.

Yet, pity the French. They've had preeminence of language, the culinary arts, fashion and class wrested from their tobacco-stained, Brie-smeared fingers. Now, they're poised to lose that special prestige that can only arise from being the repository of a unit of measurement.

I'm going to drown my sorrows in a glass of Cabernet (Napa Valley of course).

Comments:
They already lost the meter and the second. The first was for a long time a platinum bar kept at standard temperature, with a duplicate mounted on a wall somewhere in Paris - so whenever you bought a new meter-stick, you could check it out against the Standard. I always thought that was a great idea.
 
"A meteor could strike Paris - destroying the prototype," Mohr pointed out. "The watt balance can always be recreated."

Sounds hopeful.
 
When did the French lose the second and to whom and how? And what is the watt balance and what does it do?
 
The second is now defined in terms of the oscilations of a cesium atom under certain conditions. Basically, you get a pile of cesium, do some stuff to it, and count the time for it to vibrate some particular very large number of times. That's a second.

Dunno what a Watt balance ie.
 
Apparently the metal bar has been obsolete for some time. The current definition of a meter has been

"Length traveled by light in vacuum during 1 / 299 792 458 of a second."

since 1983.

http://lamar.colostate.edu/~hillger/meter.htm
 
The idea of a platinum kilogram is a bit scary considering what a madman with a file could do to standards--not to mention dieters--everywhere!
 
Re: " Apparently the metal bar has been obsolete for some time. The current definition of a meter has been 'Length traveled by light in vacuum during 1 / 299 792 458 of a second.' since 1983."

Which explains why, in making sure your meter stick is exactly the right length, you need a VERY accurate stopwatch.
 
Stop watches these days are accurate to one part in ten to the eighteenth.

Time is the easiest thing in the world to measure accurately.

Next in accuracy is measuring wavelengths of light. This is especially true since the advent of the laser.

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A watt balance measures forces by using currents to create counter forces.
 
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