After 130 years of faithful service to mankind Le Grand K – the earth’s reference kilogram – will officially be retired on 20 May 2019. Yesterday’s (16 November 2018) vote at the International Bureau of Weights and Measures General (BIPM) Conference on Weights and Measures in Versailles, France doesn’t dramatically change anything about the the world you live in. But you can be safe in the knowledge that your world will become a more accurately measurable place.
So what went down? The kilogram is no longer defined by the platinum alloy International Prototype of the Kilogram which is stored at the BIPM headquarters in France, but rather by a fundamental constant of quantum physics. In 1900 physicist Max Planck derived an equation that matched the then accurate measurement of black body radiation. A black body absorbs all light by reflecting the electromagnetic waves internally. Planck’s constant then relates the energy of light to the frequency of the wave. Albert Einstein later (1905) hypothesized that a quantum light particle is electrically neutral and birthed the idea of the photon.
Because energy is related to mass, you can apply Planck’s constant to derive a specific mass. It’s nature informing science through the laws of physics and not our lizard brains trying to recreate nature.
You see, up until this point we had a reference design weight that would need to be either accessed or copied to provide accurate measurement throughout the world. Now anyone can simply apply a constant that has been thoroughly tested.
The broader implications for the International Sytem of Units (SI) is wild. Alongside the kilogram, the ampere, kelvin and mole were also redefined and tied to physical constants. An amp is now defined by the elementary electrical charge (e). Kelvin is now defined by the Boltzmann constant. And the mole is bound by the Avogadro constant.
“The SI redefinition is a landmark moment in scientific progress,” said Martin Milton, Director, International Bureau of Weights and Measures (BIPM). “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.”
“Today marks the culmination of decades of work by measurement scientists around the world, the significance of which is immense,” said Barry Inglis, Director of the International Committee for Weights and Measures. “We will now no longer be bound by the limitations of objects in our measurement of the world, but have universality accessible units that can pave the way to even greater accuracy, and even accelerate scientific advancement.”
For a better explanation, here’s someone a lot more knowledgeable than me explaining it more eloquently: