What is a kilogram?
Easy. It's 2.2 pounds.
This humble measurement is hugely important in certain fields - think medicine, engineering and technology - that keep our world turning. So if the official standard by which it is determined gets off by a few ticks, it could throw a huge wrench in those wheels.
The Sound of a Single Atom
And that's exactly what's happening: the standardized weight that represents the true kilogram – a table tennis-sized cylinder made of platinum and iridium that sits in a vault at the International Bureau of Weights and Measures (BIPM) in France – is shrinking.
Le Grand K, as the orb is called, is the only physical object still used to measure a standardized weight or measurement. The remaining six – the second, the meter, the kelvin, the mole, the candela and the ampere – are measured relative to a fundamental natural constant, National Geographic reports.
Now scientists want to make the same shift for the kilogram, because if the weight didn't depend on a physical object it wouldn't be subject to the environmental forces around it.
It's not clear whether Le Grand K itself is shrinking – perhaps due to outgassing – or the official replicas are gaining weight because they come into contact with outside world more often.
Le Grand K currently weighs about one grain of sand less than its twins, reports Mental Floss.
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"The big joke is, if someone were to sneeze on the kilogram, there are about 10 fundamental constants that would change, because they're all tied to its value," optics and mechanical engineering professor Jonathan Ellis said in a release.
The question is: how?
Two possible methods are under investigation. One uses a watt balance, which is a device that determines mass by calibrating mechanical and electrical power. But it has real world limitations. Scientists are actively working to find a way to overcome those.
The second is called Avogadro's Number. It involves a very large group of atoms that can be translated into grams and used to determine the mass of a kilogram.
Video: Time to Switch to the Metric System
If either of those methods prove successful, what happens to Le Grand K?
Perhaps the scientist who cracks the code can inherit the century-old weight -- it could make a beautiful centerpiece.