The Kilogram As We Know It, Is No Longer

For 130 years, a kilogram has been defined by a lump of metal sitting in a vault in Paris. Not anymore.

At the General Conference on Weights and Measures (yes, this is a real thing), in Versailles, scientists from more than 50 nations weighed in on the historic vote.

Scientists were incredibly proud of this moment that has been decades in the making, with tears shed by many of those involved in the vote.

Others, like these researchers from the National Institute of Standards and Technology in the U.S., had a more permanent approach to their celebrations, by tattooing the re-defined unit onto their arm.

"After 30 years of very hard work, 30 years of many scientists working in different laboratories in our 60 different members states, to get their scientific equipment working together so it all produces the same results at the international level," said Martin Milton, director of the International Bureau of Weights and Measurements (this is also a real thing).

How Has The Kilogram Been Measured Until Now?

By a chunk of metal. Or more accurately, a cylinder of platinum alloy called the 'International Prototype of the Kilogram', or 'Grand K', has been the official kilogram measurement since 1889.

It has been locked away in a vault at the Bureau's headquarters in France, and has just six official replicas.

A mass etalon, a copy of the original 'Grand K' rests under its double glass dome during the International General Conference of Weights and Measures. Image: EPA
Why Has The Grand K Been A Problem?

Because theoretically it doesn't always weigh the same. Despite being kept in three glass bell jars to protect it from the elements, it still does collect dust and tiny particles.

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Dust may not seem like it weighs much, but for an object that is the official standard of a  measurement, even the slightest change effects the weight.

The Grand K is also taken out for cleaning, which can affects its mass. Changes in atmosphere can also affect its mass.

In theory, if there is less mass in the Grand K, its atoms would have to weigh more because the base kilogram (the Grand K) is, by definition, always a kilogram.

The opposite works in reverse, if the Grand K has more mass then atoms would theoretically weigh less.

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“We will now no longer be bound by the limitations of objects in our measurement of the world, but have universally accessible units that can pave the way to even greater accuracy, and even accelerate scientific advancement,” said Doctor Barry Inglis, who is the first Australian to be President of the International Committee of Weights and Measurements.

So What Will Replace The Grand K?

Scientists now have the 'Planck Constant' which looks like this -- 6.62607004 × 10-34 m2 kg / s. Say what?

It is derived from quantum physics, and with a Kibble balance -- a flawlessly accurate weighing machine -- can be used to to calculate the mass of an object by using a precisely measured electromagnetic force.

“The SI redefinition is a landmark moment in scientific progress,” said Milton.

“Using the fundamental constants we observe in nature as a foundation for important concepts such as mass and time means that we have a stable foundation from which to advance our scientific understanding, develop new technologies and address some of society’s greatest challenges.”

Does This Mean We Weigh More Or Less Now?

Sadly, not at all. The purpose behind this change is to create a constant way of measuring a kilogram.

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Image: Getty

In fact, the exact implications of the changes on everyday life aren't yet known, but Bruno Jacomy, ‘Made to Measure, Seven World Units’ exhibition curator, believes the possibilities are endless.

"If we think about what happened a few years ago, when the meter was redefined in relation to the speed of light, a few years later we saw the creation of the GPS," he said.

"This was something previously unimaginable and was unthinkable if there hadn't been this new definition."

The new definition will come into effect in May 20, 2019. But life for ordinary folks, remains much the same.

With Reuters 

Featured image: Getty Images

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