Experts are currently attempting to redefine the kilogram through the help of Avogadro's number and the Planck constant, instead of relying on a piece of metal, which is under the control of France.

Scientists from Japan, Italy and Germany are looking at averaging the most precise measurements of the Avogadro's number, which is a fundamental constant that can help change the definition of the kilogram by 2018.

Avogadro's number refers to the number of tiny particles, such as atoms and molecules, present in a "mole" of an object. This constant helps to translate tiny particles into more significant quantities, is associated with other physical constants and can be used to convey measurement units.

In 2011, scientists came up with a new value for Avogadro's number, which is said to have an uncertainty rate of approximately 30 atoms per billion. This was followed by another discovery of a new value for the constant, which is said to have an uncertainty rate of about 20 atoms or less per billion, a drop in the earlier modification.

The scientists then decided to correlate the two new values and get their average to come up with a neutral value that may be more accurate. The resulting value is 6.02214082(11)x10^23.

The kilogram is a unit of measurement that is dictated by a piece of cylinder made up of 90 percent platinum and 10 percent iridium. The golf-sized metal is currently located in the International Bureau of Weights and Measures in Sevres, France.

However, with more scientists attempting to pursue more studies, limiting their options to one standard, where objects must be calibrated, is considered a hindrance to progress. Another point of concern of scientists is that the metal has undergone changes in surface reaction, making more room for errors.

For these reasons, a community concerned with international metrology aims to pattern the kilogram according to a constant of physics, without having to depend on a single physical object. The researchers discussed for a couple of years the plan for redefinition, and they have finally decided to pattern the change after the Planck constant, which relates the quantum action of particles.

The plan for redefinition is a tedious endeavor.

"Prior to redefining the kilogram, we must demonstrate that the new realization is indistinguishable from the present one, to within the accuracy of the world's best balances," said Giovanni Mana, one of the lead researchers on the new paper. Initiating such a big change will affect many industries around the world and a wide range of adjustments must be made, subjecting processes to errors.

Basing the new definition of the kilogram from the Planck constant necessitates the development of precise systems to accurately measure against the Planck constant and Avogadro's numbers.

Photo: Dominic Melton | Flickr