how much does a kilogram weigh? depends on your \'planck constant\'
This may not change the way you buy bananas, but scientists have voted to redefine the value of 1 kg, which they call a landmark decision, which will improve the accuracy of scientific measurements.
Starting at 1889, the 1 kg is defined by a shiny platinum block
The Iridium star has a special glass box called the international prototype of the kilogram.
The Centre is based at the International Bureau of Weights and Measures (
The French initials acronym is BIPM)
Right outside Paris.
BIPM members of about 60 countries agreed on Friday a week later --
A long meeting was held at the nearby Palace of Versailles to redefine 1 kg with a tiny but unchanging value called the \"Mapu constant.
They also voted to update the definition of amps (
Current), the kelvin (
Thermodynamic temperatureand the mole (
Amount of material).
All modern mass measurements are derived from kilograms, whether it is micrograms of medicine or gold dust, kilograms of fruit or fish, or tons of steel.
The problem is that the weight of the prototype is not always the same.
Even in its three glass bell jars, it absorbs particles of dirt and is affected by the atmosphere.
Sometimes it needs to be cleaned, which will affect its quality.
This may have a profound impact.
If the prototype loses mass, the weight of the atom would theoretically be greater, because by definition the base kg must always be 1 kg.
For decades, scientists have been trying to define a constant value for kilograms that comes from immutable physics, as they do for other standard units (SI units)
Supervised by BIPM.
For example, 1 m is not 100, it is actually \"the length of the path that light travels in a vacuum at a time interval of 1/299 seconds and 792,458 \".
The \"Mapo constant\" derived from quantum physics, which can be used with the Kibble balance, is a precise weighing machine that calculates the mass of an object using a precisely measured magnetic force.
\"SI\'s Redefining is a landmark moment in scientific progress,\" said BIPM director Martin Milton . \".
\"Using the fundamental constants we observe in nature as the basis for important concepts such as quality and time means that we have a stable foundation to advance our scientific understanding and develop new technologies, solve some of the biggest challenges in society.
Barry ingries, head of the body weight and measurement board, said this has had a huge impact.
\"In our measurements of the world, we will now no longer be limited by objects, but have generally accessible units that can pave the way for higher accuracy, even accelerating scientific progress. \"
This can be said to be the most important re-definition since the recalculation of the second SI unit in 1967, a decision that helps simplify communication around the world through technologies such as GPS and the Internet.
The new definition agreed upon by the BIPM will take effect on May 20, 2019.