Tuesday, March 01, 2005

Kilogram: Out of fashion?

The Kilogram (as with the meter*), the basic unit of mass in the SI system, equal to 1000 grams or 2.2046 lbs is moving towards a new definition based on a universal constant. The intention of the scientists working on this is to switch the kilogram from being defined by a physical model to a constant. A paper released on Monday proposes redefining the unit via fixing the values of one of two well-known universal constants. Avogadro’s Constant Matter is made of molecules, which are the smallest division that share all the chemical properties of the bulk material. Those molecules are made of atoms that are comprised of protons and neutrons. To a very good approximation, protons and neutrons have the same mass which is one AMU (Atomic Mass Unit). Since atoms and molecules are built from these protons and netrons, their masses are expediently measured in these units. Simply put Avogadro’s number is nothing more than a conversion factor between AMUs and grams. Planck Constant Planck constant on the other hand states the mathematical relationship between the frequency of an electromagnetic wave and the energy in that wave, and is often used to explain the sizes of quanta, which are tiny electromagnetic packets. Planck is represented by the letter h and has a value of 6.63 × 10^−34 J-sec. The combination h/2π, denoted by h (called “h-bar”), occurs frequently. So what’s wrong with our current model? In 1889, a cylinder of a platinum-iridium alloy was declared the international standard of measurement for the kilogram. It's kept at the Bureau International des Poids et Mesures in France, and several copies were distributed around the world. It's unclear if the principal cylinder's mass is increasing or decreasing, scientists said, because it is the object used to measure others. Still, this poses a concern. Another worry is the possibility of the main model's destruction, come a natural disaster So the idea is to have some kind of definition to be able to construct the kilogram just given this information, without an object. Interesting. You can read more about it http://www.iop.org/EJ/journal/Met --------------------------------- * Back in the days when the meter was a pair of lines on a bar kept in a box in Paris, the speed of light was a number that was measured. When it became clear that our distance standard (the physical bar) was limiting the precision with which we could measure the speed of light, we changed the standards to something more precise and repeatable than the use of this physical artifact. The first change was to specify a certain number of wavelengths of a particular transition frequency, but this defintion was found wanting. So eventually the meter was defined in terms of the speed of light, because that allowed for the most precise and repeatable definition of the meter.


Anonymous said...

i think using plank would be ridiculous…. Avagrado is the way to go!

Yazan Malakha said...

Actually Planck has as much of a chance as Avogadro does... If not slightly better, in my opinion. It would yield better precision in electrical measurements and facilitate precise calculations in studying the quantum properties of atoms.

How does it work?
It would measure a kilogram against magnetic force using an experimental device called the “Watt Balance”. A kilogram mass is placed on a balance plate that is surrounded by a coil of copper, that is surrounded by another superconducting coil. The magnetic field produced by sending electricity through the coils pushes the plate to counterbalance the object’s weight. The amount of electric current and voltage is then related to the Planck constant in order to define the Kilogram.

I hope this explains how Planck would be utilized to define the Kilogram. I’m still waiting on reading the final paper to be published on Metrology. I’d be able to make a sound judgment then.

Best Regards,
Yazan Mj Malakha

T. Qsous said...

Thanks, but what about Avogrado? Can you explain that one too?

Harvy Pothead said...

Intellectually, I'm all for changing the model for which we base the kilogram, if its currently built around an unstable base, but I have to wonder-- what happens to the drug trade? Will the base price for a kilo of pot go up or down?

I do all of my business with pot on the ounce level, kind of side stepping this GramGate by virtue of not buying too high of quantity or too low of quantity, but I'm sure that there are folks who do deal with it in the larger weight who will either have to pass the savings on to me or charge me more for their new overhead, and that could lead to some interesting situations.

Will it fuck with old school potheads forever? By 2007 the change looks to be in place; does this mean that all of the dealers have to go out and get new scales if they're relying on digital metric ones now? Will the phisheads cry foul?

Seems like a sticky-icky situation to me.

Yazan Malakha said...

Hello T. Qsous,

Avogadro involves counting the number of atoms in a specific atomic mass that equal 1 kilogram. It involves using X-ray to measure the space between atoms in a perfect crystal in order to be able to estimate the size of each atom. By measuring the density of the crystal and the weight of atoms we get the number of atoms equivalent to 1 kilogram.

I don't know if there's anything as close to a PERFECT CRYSTAL. Either method will have positive ripple effects on many other physical constants however, such as the charge and mass of electron for example, the uncertainty of some constants would be reduced to zero. The specifics will depend on which definition is chosen.

I would suggest reading the following articles

Measuring the Plank Constant The BIMP watt balance Now on to the fuss Harvy created… a kilogram would still be 1000 grams, thus the kilo you pothead, the way it’s defined will be different that’s all. I doubt it will have any profound effect on weed/ganja prices. Either way, I’m looking forward to establishing our Amsterdam Pot Café.

Yazan Mj Malakha

Harvester Of Sorrow said...

I still wonder if pot prices will go down..we should start thinking of the café’s name!