Kilo prototype mysteriously loses weight

[cybernomad]

To solve a mystery don't create new physics for one case.

 

[rewebster]

Part of the problem could be in the shape even; (I'm thinking that the loss could be from multiple reasons)--besides loss from evaporation and/or sublimation, the 'cylinder' shape may not help. Even if the 'weight' has only been 'picked up' three or four times, the shape adds to an 'amount' of friction along the sides for the size and weight. Someone has to have a strong grip to lift such a weight for the size, and the amount of grip on the sides has to have a microscopic 'sandpaper' effect to the sides of the cylinder.

A better shape may have been a mushroom shape where the lifting could be applied to the 'underneath' lip as to not apply any 'friction'.---and the metal atoms/molecules/alloy may have not the 'best' intra-bonding between them for the metal itself.

I think if there could have been found a strong dense crystal that had been 'found' in similar environmental surroundings as what they like to store the weight, and shape it like a mushroom/'lipped' design--that may have been better with a single atomic layer of 'something' to 'see' if there was any loss from the handling.--and put diamonds at the 'lift' points on the underneath side for diamond tipped lifting devices.

They could 'test' whether there is any loss by evaporation or sublimation by putting the 'cylinder' in a contained jar and test the air later for particulates, etc.

I'd set up three or four other 'test jars' to test the 'air' /'some other gas' for material used for/in the jars, and/or even in a vacuum to see if 'anything' gets 'sucked' out of the cylinder. Even if the original cylinder was 99.9999 % 'pure' (good old Ivory soap at 99 44/100ths), that still leaves room for 'impurities'.

 

[Ivan Seeking]

It has been determined that this is the fault of George Bush.

The universe can only sustain a finite amount of spin.

 

[billiards]

The Earth burped.

That's what I was thinking, if g changed slightly in Paris then the weight would change accordingly. The lowering of g could be achieved by a very slight amount of tectonic uplift.

Also: the kg should be standardized too a precise number of carbon atoms or something.

 

[Gokul43201]

That's what I was thinking, if g changed slightly in Paris then the weight would change accordingly. The lowering of g could be achieved by a very slight amount of tectonic uplift.

I think we can rule that out because any comparison of masses (or weights) would require both objects to be at the same place (eg: in Paris).

Also: the kg should be standardized too a precise number of carbon atoms or something.

And how would you go about counting these atoms?

 

[NeoDevin]

And how would you go about counting these atoms?

Have your grad student do it...

 

[billiards]

I think we can rule that out because any comparison of masses (or weights) would require both objects to be at the same place (eg: in Paris).

Oh right, I was not aware that they had carried out the calibration at the same location, although now I think about it I don't see how else they could have really done it. In this case I will go with the "mass changed due to handling" argument, because in order for the masses to be in the same place at once, it is necessary for them to be handled.

And how would you go about counting these atoms?

Counting them? No. I wasn't thinking aong those lines, I was thinking more along the "how would you tell an alien species what a kg was?" pattern of thought. You could specify a finite number of carbon 12 atoms and then they could interpolate the exact weight you meant by integrating knowledge of the weight of a carbon 12 atom (which should be universal) in terms of their own practical weighting system.

 

[Moridin]

Scientists have been trying to find a natural reference for the kilogram for quite some time - as it is the only one left (of the SI base units) that is defined by a man-made object. The atomic mass unit has been proposed but there are a few problems, as hinted above. We can compare objects of a human size with the standard kilogram quite well, and compare the mass of atoms and so on compared to the carbon-12 atom, but the tricky part is between the two.

 

[mgb_phys]

Have your grad student do it...

There is a project to do this with a silicon sphere and use x-ray crystalography to precisely measure the atomic spacing then use the size of the sphere to calculate the number of atoms present. ( details in my post above)

At the moment this looks like a better bet than the Planck balance.