Kilogram faces quantum diet after weight problem

[dipsydoodle]

The guardians of the world's most important standards of weights and measures have turned to the weird universe of quantum physics to try to resolve a dilemma.

To the bafflement of scientists, a cylinder of metal sitting in a closely-guarded strongbox that is the global benchmark for the kilogram is changing mass.

The enigma doesn't affect anyone who wants to buy 500-milligramme tablets of aspirin, half a kilo of carrots or a 50,000-tonne cruise ship.

But it poses a hefty theoretical challenge to physicists, and complicates the work of labs which need ultra-precise, always-standard measurement.

http://uk.news.yahoo.com/kilogramme-faces-quantum-diet-weight-gain-131735537.html

[Cirque du So-What]

1. This was quite the topic when I was in grad school and the weight problem first noticed

Even back then, I favored switching to a value based upon Planck's constant (as suggested in the article). Doesn't surprise me to find that coming up with a solution is proceeding at a glacial pace.

[MineralMan]

2. Hah! I knew the metric system was bogus.

We should never have used it in the first place. Real measurements are made in terms people can understand:

A pint's a pound the world around.

An ounce is the weight of a butcher's thumb.

A yard is the length of the king's stride, damnit!

A foot is a third of a yard, by golly.

All this metric stuff is just French mollycoddling. Give us human measurements we can all understand!

/rant

:rofl:

[dipsydoodle]

3. However

>

In 1824, the British abandoned both the Ale and the Wine gallons in favour of the Imperial gallon, based on the volume of 10 pounds of water (which works out at 277.41945 cu in). America, by this time, had already standardised on the Wine Gallon of 231 cubic inches (strictly speaking, this was defined as the volume of a cylinder 6 inches long and 7 inches in diamete, or, using the old approximation for pi, 231 cubic inches).

The result is that the US gallon is 83.267% of the British gallon. In more usable terms, the British gallon is about a fifth greater than the US gallon, and the US gallon is about 5/6 of the British gallon (or a little under 7 British pints)

>

The reason for his is that, in the British system, a gallon of water weighs 10lbs, or 160 ounces, and so there are 160 fluid ounces in a gallon, and 20 fluid ounces in a pint - from this, it follows that a fluid ounce of water does actually weigh an ounce.

Therefore, an American fluid ounce is greater than the British fluid ounce by about 4%, and an American flluid ounce of water doesn't weight an ounce.

http://www.miketodd.net/encyc/measures1.htm

:)

:hi:

[MineralMan]

5. Yeah, but we kicked British butt and got our own country, so

a pint's a pound, and that's that! If it hadn't been for their weird money system, that nobody in their right mind could ever decipher, we might still be British subjects. Pence, shillings, pounds, crowns, guineas...what the heck is that all about? I wouldn't give a ha'penny for all the thrupence on the planet. And what can you buy for a farthing nowadays? That's what I'd like to know.

[AlecBGreen]

12. heh! so THATS what that means...

"A pints a pound the world around..."

I always thought it was about the price of beer :blush: Derp!

[muriel_volestrangler]

9. But - the US pound is defined in terms of the kilogram

http://www.ngs.noaa.gov/PUBS_LIB/FedRegister/FRdoc59-5442.pdf

And so was the British pound: http://en.wikipedia.org/wiki/Pound_%28mass%29#Relationship_to_the_kilogram

You have been metricated, even if you don't know it.

(And a yard was the distance from outstretched thumb to nose of a king, not a stride: http://www.npl.co.uk/educate-explore/factsheets/history-of-length-measurement/history-of-length-measurement-%28poster%29

[Confusious]

13. We didn't send a man to the moon with the metric system!

Said by a mechanical engineer I know.

[PoliticAverse]

4. Maybe they just need to dust it... n/t

[Ikonoklast]

6. As the Universe expands, it also becomes less dense.

[frogmarch]

7. What? The article says

It is unknown whether the cylinder gained weight, or whether it lost weight. It is only known that its weight has changed.

Guess I need to reread the article.

[FiveGoodMen]

8. This is some great science reporting!

"There used to be a platinum ruler that was the world's standard metre until its role was replaced by a fundamental constant, the time that light takes to travel 100 centimetres. The metal metre still resides in Sevres, but as a museum piece."

No, goddamnit, a meter is not the fucking TIME that it takes to go anywhere.

And OF COURSE 100 centimeters is a meter.

FAIL.

[jakeXT]

10. If you know the speed of light and you have good clock.... nt

[FiveGoodMen]

11. Yes, go on, finish that

If you know the speed of light you can define the meter by how far light travels in a certain amount of time, but ...

"...the time that light takes to travel 100 centimetres" means the same thing as "the time it takes light to travel a meter"

Well, obviously light can travel a meter in the time it takes light to travel a meter.

How is that a definition?