Kilogram sliming down...
-
Official prototype of kilogram mysteriously losing its weight [^] :omg: (50 micrograms compared with the average of dozens of copies...so far) Steve
You've got it all wrong. It's not about weight loss, it's about slime! Sounds vaguely (perhaps blatantly) political.
-
or cause wary waistline-watchers to re-examine their weights: 50 micrograms is roughly equivalent to the weight of a fingerprint. New diet patent - eat sandwich with gloves on. Guaranteed minimum 500 microgram weight loss per day per sandwich (400 if you eat with pinkies raised.)
Gary
-
Official prototype of kilogram mysteriously losing its weight [^] :omg: (50 micrograms compared with the average of dozens of copies...so far) Steve
Basing the standard kilogram on a physical object seems unreliable to me. Why not base it on something objective and timeless, like the mass of a specific number of atoms of a specific isotope of an element?
-
Basing the standard kilogram on a physical object seems unreliable to me. Why not base it on something objective and timeless, like the mass of a specific number of atoms of a specific isotope of an element?
probably the difficulty of counting the number of atoms precisely enough in a usefully large sample. 1g of atomic Hydrogen contains ~6*10^23 atoms. All the other periodic redefines have been done when problems begin to surface with the old definition, until it breaks there's no point in spending money to fix it afterall. This issue probably will result in a new definition at some point in the medium near future.
-- If you view money as inherently evil, I view it as my duty to assist in making you more virtuous.
-
probably the difficulty of counting the number of atoms precisely enough in a usefully large sample. 1g of atomic Hydrogen contains ~6*10^23 atoms. All the other periodic redefines have been done when problems begin to surface with the old definition, until it breaks there's no point in spending money to fix it afterall. This issue probably will result in a new definition at some point in the medium near future.
-- If you view money as inherently evil, I view it as my duty to assist in making you more virtuous.
The difficulty in counting atoms is probably not that great. As you mentioned, 6 * 10^23 (a "mole") is commonly used in the specification of a gas' mass. In any case it's highly unlikely that uncertainties in atom count would cause as large a variation as has been observed in the official kilogram. Defining mass units in terms of atoms (which don't change mass) seems more stable to me.
-
The difficulty in counting atoms is probably not that great. As you mentioned, 6 * 10^23 (a "mole") is commonly used in the specification of a gas' mass. In any case it's highly unlikely that uncertainties in atom count would cause as large a variation as has been observed in the official kilogram. Defining mass units in terms of atoms (which don't change mass) seems more stable to me.
-
Official prototype of kilogram mysteriously losing its weight [^] :omg: (50 micrograms compared with the average of dozens of copies...so far) Steve
This 2003 article gives more detail than the brief piece the AP circulated yesterday.
-
Official prototype of kilogram mysteriously losing its weight [^] :omg: (50 micrograms compared with the average of dozens of copies...so far) Steve
It's Bush's fault.
-
Basing the standard kilogram on a physical object seems unreliable to me. Why not base it on something objective and timeless, like the mass of a specific number of atoms of a specific isotope of an element?
Actually, I think there are currently two international standards committees examining ways to define the kilogram without relying on a physical object. One committee is looking at defining the kilo by counting atoms (I think they are trying to use ultra-pure silicone) and the other is coming at the problem by defining it in terms of force and has something to do with the speed of light.
-
Official prototype of kilogram mysteriously losing its weight [^] :omg: (50 micrograms compared with the average of dozens of copies...so far) Steve