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Kilogram Reference Losing Weight
doubleacr writes "Ran across a story on CNN that says 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. Physicist Richard Davis of the International Bureau of Weights and Measures in Sevres, southwest of Paris, says the reference kilo appears to have lost 50 micrograms compared with the average of dozens of copies.""
Weight is a property independent of the units you measure it with.
The object which defines the Kilogram is getting lighter (the fact that it is getting lighter is independent of this object's role in defining the Kilogram), ergo the definition of Kilogram is getting lighter. We all weight the same, we'll just use a slightly bigger number to describe how heavy we are.
The enemies of Democracy are
I doubt there's any equipment sensitive enough to detect weight difference in an object that was moved several feet but there is a change.
According to the back of this envelope here, the weight change from raising a kilogram by one metre would be
about equivalent to reducing its mass by about 3 parts in 10^7, i.e. 300 micrograms. The article says the measured loss was around 50 micrograms. So I guess there is equivalent sensitive enough to measure that.
Unless I was off by a few orders of magnitude...
Yes, but at what temperature/pressure? Both of these things affect the density of water as well. I'm assuming its STP or 25C and 1atm. Then again, how exactly do you go about measuring that...
If you are about to mod me down, keep in mind that this post was most likely sarcastic.
Put a warning label weighing 50 micrograms that says:
WARNING: Measurements are approximate
Problem solved.
WARNING: Smartphones have side effects--most of them undocumented.
in terms of planck mass. The planck constants are (to the best of our current knowledge) invariant since they are all based off universal constants (like the speed of light or the gravitational constant).
The planck mass is defined as the mass for which the Schwarzschild radius is equal to the Compton wavelength over Pi.
The Schwarzchild radius is 2Gm/c^2, while the Compton wavelength = h/mc = 2*pi * dirac's constant/(mc). (I'll refer to dirac's constant as d, since I don't know how to type the proper character).
Setting the two equal yields 2Gm/c^2 = 2d/mc => m= sqrt(dc/G). Then, we could define 1 kg as 45940892.447777 planck masses. The only thing's we're assuming as constant are the speed of light, the universal gravitational constant, and planck's constant.
Engineering is the art of compromise.
clearly fabricated. Angels are old school. They all use vi.
"Well, why wouldn't the copies' atoms be drifting off as well?"
They are, but not at identical rates.
much as a pint of water weighs a pound (the world around, and takes 1 BTU to raise temperature by 1 degree F).
You've got a strange definition of world there.
On this side of the pond:
"A pint of water weighs a pound and a quarter"
I'm ashamed to have to say that it appears the majority of my countrymen would prefer to use "fundamental" units that have rhyming mnemonics rather than units that make all the calculations simple and consistent across the world.
http://news.bbc.co.uk/1/hi/uk/6637587.stm
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
I had this explained to me in the mid '90's by someone who was involved in printing. With variable width fonts, you are no longer supposed to use two spaces, the typeface is supposed to leave an adequate gap. Two spaces is left over from the days of typewriters.
I Do C++