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Posted: Thu Sep 27, 2007 1:25 pm
by Galactic Groove
not sure if only 200 years would be long enough (if indeed they were created in 1800), but what about the half-life of the material the cylinder is made of?
EDIT: Nevermind, if it's Platinum then there is no halflife. But then again, what if there were other impurities present in the cylinder?
Posted: Thu Sep 27, 2007 5:32 pm
by BMAONE23
Electrons have mass weight, though the entire mass might become unstable if too many were ripped free from theit host atoms, but could those few ambient cosmic rays that manage to reach the earths surface cause a gradual stripping of electrons from the mass?
Posted: Thu Sep 27, 2007 7:48 pm
by jimmysnyder
BMAONE23 wrote:Electrons have mass weight, though the entire mass might become unstable if too many were ripped free from theit host atoms, but could those few ambient cosmic rays that manage to reach the earths surface cause a gradual stripping of electrons from the mass?
The lack of 50 micrograms worth of electrons would render the mass so positively charged it would flash sparks reaching all the way to Aix-la-Chapelle
Posted: Thu Sep 27, 2007 9:41 pm
by rigelan
Well, masses are measured using balances.
The force of gravity upon the mass is compared to the force of gravity upon a second mass. If the gravity had changed, it should have absolutely zero effect upon the mass of the iridium-platinum kilogram standard. The balance would still be level because both masses would have less gravitational force upon them.
Posted: Fri Sep 28, 2007 5:10 am
by BMAONE23
rigelan wrote:Well, masses are measured using balances.
The force of gravity upon the mass is compared to the force of gravity upon a second mass. If the gravity had changed, it should have absolutely zero effect upon the mass of the iridium-platinum kilogram standard. The balance would still be level because both masses would have less gravitational force upon them.
Nice Point
![Idea :idea:](./images/smilies/icon_idea.gif)
Posted: Fri Sep 28, 2007 9:44 pm
by jimsaruff
Very good point, rigelan.
So how do you think they determined there was a 50 microgram difference?
Posted: Sat Sep 29, 2007 12:01 am
by geckzilla
Because there were a bunch of them distributed all around the world so that other countries would have their own means of discerning the weight of the kilogram. The difference wasn't caused by the one weight by itself but rather its comparison to the other weights. Well, that's what I read anyway.
Posted: Sat Sep 29, 2007 6:57 pm
by goredsox
Hey I thought a kilogram was the weight of a liter of water under certain precise conditions (temp, pressure). I didn't know the definition was dependent on a musty old block of platinum locked up in France.
Also the news article said it contained Iridium too. Doesn't that decay?
Posted: Sun Sep 30, 2007 12:37 am
by geckzilla
Assuming they used a stable isotope, nope.