Official prototype of kilogram mysteriously losing weight

Official prototype of kilogram mysteriously losing weight

www.cnn.com

The 118-year-old cylinder that is the international prototype for the metric mass, kept tightly under lock and key outside Paris, is mysteriously losing weight -- if ever so slightly.

(visit the link for the full news article)

I'm wondering if the reported change in weight is due to the materials contained that comprise the weight (platinum and iridium alloy), or if there are external factors here at play.

www.cnn.com
(visit the link for the full news article)

Wow, interesting. Maybe it's losing weight due to natural decay?

Originally posted by Beachcoma
Wow, interesting. Maybe it's losing weight due to natural decay?

Maybe some sort of atmospheric changes are causing it to decay.. although that depends whether or not it is held in an airtight container or not.

I would guess that it's slightly contaminated with a radioactive isotope and loosing mass through radioactive decay.

reply to post by Golack


That's exactly what I was alluding to. I can't really come up with a better explanation.

That's why they are making 2 perfect spheres at that Australian company. They are using silicon I believe into basically, glass balls.

It's not radioactive decay. The scale is not even close.

50 micrograms = 1/100,000,000th of a kilogram.

Remember your basic science. Avogadro's number is 6.02x10e23 atoms/mol

A mole is the atomic number of the element. Thus:

The kilogram is the mass of exactly (6.022 1415 × 10e-23/0.012) unbound carbon-12 atoms.

Electrons - an electron mass is 9.109 3826(16) × 10e-31 kg

Radioactive decay involves electrons. So even with substantial decay, the numbers would not be on the order of 10e-8, but 10e-31.

That's 23 orders of magnitude. So it's not decay.

I'm guessing that just handling, cleaning, etc. could make more of a difference. Though they make an effort not to 'touch' the standards leaving a fingerprint (which would be that weight in oils from the body), it may be possible that the standard was dropped, or mishandled and perhaps the corrosives in sweat could make it lose some mass.


Edit: corrected Avogadro's Constant



[edit on 13-9-2007 by Badge01]

reply to post by amehrich


for what its worth the Britannica Concise Encyclopedia details the percentages of platinum and iridium that comprise the weight.

"The international prototype kilogram, the primary standard (see weights and measures) for weight, is made of an alloy comprising 90% platinum and 10% iridium."

Maybe there's something wrong with their scales.

"It's not clear whether the original has become lighter, or the national prototypes have become heavier,"

I suppose which is which would depend on the consistency of the prototypes. If they're all the same and only the original is lighter, there you go.

The rate of change would be most interesting to know.

Originally posted by Badge01


50 micrograms = 1/100,000,000th of a kilogram.

Remember your basic science. Avogadro's number is 10e-23

I have not been in science in quite a while but isent Avogadros number 6.023x10 to the 23rd?

and a microgram is 10 to the -6th gram, not kilogram.

Originally posted by RedGolem
I have not been in science in quite a while but isent Avogadros number 6.023x10 to the 23rd?

...and a microgram is 10 to the -6th gram, not kilogram.

Yeah, I accidentally put the '-' in there.

A microgram is 10 to the -6 gram, or 1/1,000,000 gm

...and 10 to the -8th kg, which is what I put, as 1/100,000,000 kg.

Note: I'm not a math major, and math=hard.

Thanks for noting that errant '-', though.

I think people get the point and that's looking at the proper scale for radioactive decay. In addition, for heavier elements it takes many years.

Take a quick look at the Wiki page on Radioactive Decay

The range is 10e19 years for stable nuclides to 10e-23 seconds for the unstable ones.



[edit on 13-9-2007 by Badge01]

Originally posted by Badge01


...and 10 to the -8th kg, which is what I put, as 1/100,000,000 kg.

Whoops ok yes. I just had not seen micro gram stated that way. That's what probably threw me off when you printed it as a reference to the kilo gram.

50 micrograms out of 1 kilogram over 118 years isnt really that much of a decay rate. I would still say slight radioactivity is a possibility or somebody accidentally dropped the sample and nicked a piece off

[edit on 13-9-2007 by Golack]

Its 118 years old, so may be it was measured wrong and now that we have more accurate instruments, the error was made obvious.

Btw, why is there only ONE copy of such an important standard ?
Shouldn't we have a few of them located at various places in the world? What if its destroyed, the whole economy may collapse, we measure gold using this standard, don't we?

Maybe it's like not getting lighter....

I could be like the worlds got all heavyer or something...... Man.

have they checked to measure the gravity there in Paris??

perhaps there's a hot spot beneath the crust that is developing
and making everything in that region in France under weight
as the pull of gravity would be different....

(there's a large area up in Canada near the Hudson Bay that has a 'gravitational anomaly', but that was caused by the compression of the
area by the miles thick ice cap in the recent past)

Maybe gravity is getting weaker?

Maybe planet x is coming and pulling the other direction causing felt gravity to become less?

That lump of metal will be replaced soon anyway:

A Set Of Perfect Balls, A New Standard For The Kilogram

I still think gravity is weakening in the universe. And they failed to accurately measure it when they checked the distance of the earth to the moon, because both the earth and moon are growing: Has Earth been growing?