Ethan Weisberg
C Band
1/14/19
The Redefinition of the Kilogram

During the French Revolution, many people were outraged by the arbitrary and changing units that were being used in trade and commerce. The size of a loaf of bread was constantly shrinking because of famine in the 1780s. This famine caused bakers to use less bread, but charge the same price for the loaf. This sparked outrage among the French people and a motivation to create standardized units that had roots in nature so that they were not arbitrary. They wanted these units to be fair and easily communicated, thus uniting the world in global exchange. They described their units as being “for all times, for all people,” because they were to be based on nature, never changing, and accessible for everybody. Their new measurement system began with their developing the meter. Pierre-François-André Méchain used tools to measure a quarter of the circumference of the earth (slightly inaccurately); he divided it by ten million and defined this as the meter. The French then defined their unit of mass, the kilogram as the mass of water that fills a cube with sides one meter in length.
In modern times, however, the kilogram has lagged behind the developments made to many other units. All other SI units have been changed to be based on various intensive properties of the universe. For example, the meter is now defined as the distance light travels in a vacuum in 1299,792,458seconds. The kilogram, until the redefinition, was the last unit defined as a physical object. This redefinition is incredibly significant because, not only does it complete the dream of scientists to have a system of measurements that are based on natural constants, but it also improves the precision and accuracy of the kilogram. The first flaw of the kilogram was that it was defined as the platinum-iridium object called the International Prototype Kilogram (IPK) stored at the International Bureau of Weights and Measures in France. This metal block was discovered to be losing weight after weighing it against the duplicates that were made and given to various countries, thus scientists had discovered their unit was not unchanging, and could not be “for all time.” Additionally, the method for calibrating scales was inaccurate because each scale was calibrated based off of a weight, which was calibrated based off of weight, and so on with many intermediaries before reaching the IPK, thus compounding the slight errors of each physical object.
The new definition of the kilogram seeks to define the kilogram in relation to Planck’s constant, the meter, and the second, all of which are unchanging properties of nature. This allows for more accuracy than a physical object could ever yield. The use of Planck’s constant allows for great precision because it contains 9 significant digits (6.62607015 * 10-34 Js) and eliminates the inaccuracy that derives from a changing physical object, as it is an intensive property of nature. This vote could be considered a “turning point for humanity” because we have finally completed the development of a system of measurement that can be considered, in many ways, to be natural, devoid of arbitration, because it is based on constants in nature. Lastly, the kilogram can now truly be said to be “for all times, for all people.” Having a solid piece of metal in a basement in France that changes over time, be the definition of the kilogram does not truly unite all people throughout all time, but basing it on an unchanging constant of nature that remains the same all over the world can truly be said to be “for all times, for all people.”
This will affect my life in several ways. Firstly, objects that weigh much more and much less than one kilogram will be more accurately measurable because when measured based on a physical object, accuracy decreases when the sample is much smaller or larger than the standard. This will allow pharmaceutical companies to more accurately measure chemicals, so every product or medicine containing chemicals, from shampoo to an Advil, that I use will be more accurately measured. Secondly, every product I buy, especially electronic, can be more precisely and accurately measured, and therefore more optimized. So, if I were to purchase a new device it will have been measured more precisely and accurately, and its complex infrastructure, such as continually shrinking transistors, will be closer to perfection, hopefully allowing for better performance. Lastly, the most direct impact on my life is that whenever Packer buys a new balance, it will have been calibrated using the new definition of the kilogram, which is more precise and accurate, thus the balance will also be more precise and accurate, allowing me to have less uncertainty and error in the experiments I perform in lab.

References

Marantz, A. (2014, June 13). ≤ kg [Audio file]. Retrieved from https://www.wnycstudios.org/story/kg
Materese, R. (2018, December 06). A Turning Point for Humanity: Redefining the World's Measurement System. Retrieved January 13, 2019, from https://www.nist.gov/si-redefinition/turning-point-humanity-redefining-worlds-measurement-system
Nasser, L. (2014, July 9). The Meter: The Measure of a Man. Retrieved January 4, 2019, from Radiolab website: https://www.wnycstudios.org/story/meter-measure-man
Verge Science. (2018, December 18). The kilogram has changed forever. Here's why. [Video file]. Retrieved from https://www.youtube.com/watch?v=m-fFRLWBzm8