The kilogram as we’ve known since 1889 has a very simple definition: It’s the mass of a platinum-iridium alloy that’s been kept at the International Bureau of Weights and Measures in Sèvres, France. The weight is called the International Prototype Kilogram a.k.a. Big K and has copies around the world that are used to calibrate scales and make sure the world is all singing from the same ‘scale’ sheet.
Scientists from around the world recently converged at the General Conference on Weights and Measures in Versailles, France. During the conference a vote was cast to change the definition of a kilogram instead measuring it to a universal constant in nature. This change will go into effect on May 20, 2019.
The reason for the change in measure is that ‘Big K’ is not a constant. During the last 130 years it has lost around 50 micrograms (about the mass of an eyelash) since it’s creation. Sadly, when Big K’s Kg measure changes then all the world kilogram measure also need to be re-calibrated.
With the vote now in use the Kilogram has now been affixed the kilogram to the Planck constant, a fundamental concept in quantum mechanics that can never, ever change whether on Earth or anywhere else in the universe. When the Big K was first conceived in 1889 its fitting that it was designed to be “for all times, for all people” and now that finally seems to be the case.