Lea Wong
C Band
January 14, 2019
Redefining the World’s Measurement System
Previously, the kilogram has been defined by a “cylinder of platinum-iridium — about the size of a votive candle ––” called the “Grand K,” which is just about mass of one decimeter cubed worth of water. Unfortunately, this definition failed to accomplish the original goals of those who established the metric system, as they had hoped that the system would be “for all times, for all people,” as over time, the “Grand K” had become lighter. Even though the “Grand K” lost mass, it is still exactly one kilogram, because the kilogram was defined by the mass of the “Grand K.” This is proving to be problematic, as the kilogram is constantly being used in important scientific experiments, and therefore should not be changing. Another issue with the old definition of the kilogram was that it did not fulfill the original goal of its creators, which was to have all units be based on constant, natural phenomena. One may point to the aforementioned definition of the kilogram as a decimeter cubed of water, but unfortunately, the meter, which has been defined as “one ten-millionth of the distance between the equator and the north pole,” was measured incorrectly, and is therefore not derived from a constant or natural phenomenon.2 Despite these flaws, the kilogram was still successful in facilitating communication throughout the scientific community, as it has been used throughout the world, and is the basis of many other units of measurement (eg: a Newton is defined as the “force necessary to provide a mass of one kilogram with an acceleration of one metre per second per second.”)3 Thus, in redefining the kilogram, scientists had to find a way to make it constant and reliable, while still maintaining the value of the kilogram such that previous measurements using the kilogram would not be deemed inaccurate, or so that the values of other units (such as the Newton) would change.
Now, the kilogram has been defined by taking the “fixed numerical value of the Planck constant h to be 6.626 070 15 × 10-34 when expressed in the unit J s, which is equal to kg m2 s -1 , where the meter and the second are defined in terms of c and ∆νCs.”4 There are many benefits to shifting our reliance from tangible items that can wear away or be destroyed (such as the “Grand K”) to define units, and instead defining units in terms of constants. Most importantly, we will finally have a system of measurement that can truly stand the test of time and be described using “the speed of light and other ‘constants’ of physical science” rather than physical objects, making it a “turning point in humanity.” In addition, we will be able to more accurately utilize the milligram and microgram to measure lower masses, as Materese writes, “when you use physical objects to measure things, accuracy decreases at sizes much smaller or larger than your standard.” This increased accuracy will make technology more efficient, as devices often rely on measurements to “reliably make calls, send texts, access the internet and use GPS to help us navigate.”1 This will also be beneficial to the overall accuracy and precision of science experiments involving small amounts of substances, and could even be helpful to student-led experiments if Packer bought newly calibrated scales for us to use. In that case, more accurate measurements of mass would allow for more consistency between our trials, and would also make our experimental design more accurately replicable.
Works Cited
Hosch, W. (2006, June 01.) Newton | unit of measurement. Retrieved January 9, 2019, from
https://www.britannica.com/science/newton-unit-of-measurement.
Materese, R. (2018, December 06). A Turning Point for Humanity: Redefining the World's Measurement System. Retrieved December 13, 2018, from https://www.nist.gov/si-redefinition/turning-point-humanity-redefining-worlds-measurement-system
Nasser, L. (2014, July 09.) The Meter: The Measure of a Man. Retrieved January 9, 2019, from https://www.wnycstudios.org/story/meter-measure-man.
Resnick, B. (2018, November 16.) New kilogram standard: how the SI unit of mass is being redefined.
Retrieved January 10, 2018, from
https://www.vox.com/science-and-health/2018/11/14/18072368/kilogram-kibble-redefine-weight-science
C Band
January 14, 2019
Redefining the World’s Measurement System
Previously, the kilogram has been defined by a “cylinder of platinum-iridium — about the size of a votive candle ––” called the “Grand K,” which is just about mass of one decimeter cubed worth of water. Unfortunately, this definition failed to accomplish the original goals of those who established the metric system, as they had hoped that the system would be “for all times, for all people,” as over time, the “Grand K” had become lighter. Even though the “Grand K” lost mass, it is still exactly one kilogram, because the kilogram was defined by the mass of the “Grand K.” This is proving to be problematic, as the kilogram is constantly being used in important scientific experiments, and therefore should not be changing. Another issue with the old definition of the kilogram was that it did not fulfill the original goal of its creators, which was to have all units be based on constant, natural phenomena. One may point to the aforementioned definition of the kilogram as a decimeter cubed of water, but unfortunately, the meter, which has been defined as “one ten-millionth of the distance between the equator and the north pole,” was measured incorrectly, and is therefore not derived from a constant or natural phenomenon.2 Despite these flaws, the kilogram was still successful in facilitating communication throughout the scientific community, as it has been used throughout the world, and is the basis of many other units of measurement (eg: a Newton is defined as the “force necessary to provide a mass of one kilogram with an acceleration of one metre per second per second.”)3 Thus, in redefining the kilogram, scientists had to find a way to make it constant and reliable, while still maintaining the value of the kilogram such that previous measurements using the kilogram would not be deemed inaccurate, or so that the values of other units (such as the Newton) would change.
Now, the kilogram has been defined by taking the “fixed numerical value of the Planck constant h to be 6.626 070 15 × 10-34 when expressed in the unit J s, which is equal to kg m2 s -1 , where the meter and the second are defined in terms of c and ∆νCs.”4 There are many benefits to shifting our reliance from tangible items that can wear away or be destroyed (such as the “Grand K”) to define units, and instead defining units in terms of constants. Most importantly, we will finally have a system of measurement that can truly stand the test of time and be described using “the speed of light and other ‘constants’ of physical science” rather than physical objects, making it a “turning point in humanity.” In addition, we will be able to more accurately utilize the milligram and microgram to measure lower masses, as Materese writes, “when you use physical objects to measure things, accuracy decreases at sizes much smaller or larger than your standard.” This increased accuracy will make technology more efficient, as devices often rely on measurements to “reliably make calls, send texts, access the internet and use GPS to help us navigate.”1 This will also be beneficial to the overall accuracy and precision of science experiments involving small amounts of substances, and could even be helpful to student-led experiments if Packer bought newly calibrated scales for us to use. In that case, more accurate measurements of mass would allow for more consistency between our trials, and would also make our experimental design more accurately replicable.
Works Cited
Hosch, W. (2006, June 01.) Newton | unit of measurement. Retrieved January 9, 2019, from
https://www.britannica.com/science/newton-unit-of-measurement.
Materese, R. (2018, December 06). A Turning Point for Humanity: Redefining the World's Measurement System. Retrieved December 13, 2018, from https://www.nist.gov/si-redefinition/turning-point-humanity-redefining-worlds-measurement-system
Nasser, L. (2014, July 09.) The Meter: The Measure of a Man. Retrieved January 9, 2019, from https://www.wnycstudios.org/story/meter-measure-man.
Resnick, B. (2018, November 16.) New kilogram standard: how the SI unit of mass is being redefined.
Retrieved January 10, 2018, from
https://www.vox.com/science-and-health/2018/11/14/18072368/kilogram-kibble-redefine-weight-science
