Sunday , February 28 2021

Nations gather to weigh a kilo

Carlos Sanchez, Metrology Expert at the Canadian National Research Council, is working on Kibble's balance.


If something happens as planned, there will be a new kilogram definition in the world this week.

Changes will not require any adjustment of the bathroom weight or change the potato bag. But the turning point will be to make our universal mass unit more versatile.

In short, instead of justifying it with a piece of precious metal that has been cluttered up in France, scientists have decided to recycle a kilogram as something really unchanged, linked to a mathematical cord line associated with the essential natural constants that have passed since the Big Bang bronze.

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For those who play very precisely in metrology – measuring science – in the justified world, it just slightly improves.

"I have always said that it is the best time to be the main metrologist in your country," said Alan Stile, who performed this role in Canada as Director General of the National Research Council's Metrology Research Center in Ottawa.

Dr. Steele has decided to cast a Canadian vote to adopt the new kilogram definition on Friday.

Initially, the kilogram was developed as part of the metric system, the by-product of the French Revolution, which tried to stop the traditional measures, such as the pound – an arbitrary amount returning to the Roman libra – in favor of more scientifically derived units.

Initially, the kilogram was determined as a liter of water at the freezing point. But by 1889, the states that later became part of the General Conference on Weights and Measures, agreed that the value of the unit mass was to attract something that could be measured more accurately.

They settled with a reference mass treated with platinum-iridium alloy, which has since then been the kilogram of the world's prototype.

Canada was not among the original signatories, joining the conference in 1907. But this time Canada has played a key role in replacing the prototype with a new definition that no longer depends on the physical artefact.

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"This is something we really are proud of," says Dr. Steele. "Metrology is about credibility and shows you're as good as you say you are."

What Canada is doing well is measured by a very small number known as Planck's constant, which serves as a significant increase in performance in the universe. Theoretically, a constant occurs when you divide energy into a particle of light with its frequency. In practice, this is not easy to determine. Right now, Canada has won a record by setting a small constancy value with the lowest uncertainty – about 9.1 bpd.

The device that allowed it is the Kibble Balance, a standard laboratory measuring compressor version. But by comparing the weight of two objects, the Kibble balance precisely determines the mass of one object against the magnetic force generated by the electric current flowing through the wire coil. The inventive design connects the mechanism to the electromagnetic system, thereby allowing the kilogram to always be attracted to the Planck constant.

It has long been the goal of scientists, who serve as land surveyors arbitrators. The meter and the second are defined by physical constants, such as the speed of light, for decades. But because of the difficulty of measuring Planck's constant, the kilogram has hitherto been persistent.

"It's only in the last two years, or it became clear that we could vote for redefinition," said Michael Stock, director of physical metrology at the International Bureau of Weights and Measures in Sèvres, France. He said that the effort is not dependent on modern needs, but also on the possibility that scientists will have more accurate units of measurement in the coming years.

Canada first hit the kilogram in the game in 2009, when it took Kibble's balance from Britain and, in the words of Dr. Steele, "went to the city and made almost every aspect of the experiment better and better."

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The work ultimately enabled the measurement of Canadian blue chips with a few other laboratories, which together identified the constant value of Plank and, accordingly, a kilogram.

Carlos Sanchez, part of the team that worked on the NRC, said that the challenge was not only that it was precise, but that it was a continuous uncertainty over several years due to the uncertainty of more than a dozen installations in order to achieve the best possible result

"It requires patience," said Dr. Sanchez "You have to have a plan, otherwise you can spend your life doing experiments that do nothing."

Fortunately, the NRC's experiments have led to the Palace of Versailles, where representatives from 60 countries gathered to formally approve the new definition of not only kilograms, but also units of electric current (ampere), temperature (kelvin) and particulates (mol). A unanimous vote is expected, after which the global measuring building, perhaps the greatest respect for humanity by the objective reality, will remain in the tougher position – all that apparently has not changed.

What exactly is this issue, said Dr. Steele At the end, it's all: "You want a kilogram still weighing a kilo."

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