Reflections on the redefining of the metric system

On 16 November, at the 26th General Conference on Weights and Measures in Versailles, a vote was cast to overhaul the International System of Units (SI). Historically, the kilogram was based on the mass of an actual physical object, a cylinder of platinum alloy that has been housed in Paris since 1889. This cylinder, or “Le Grand K”, weighs exactly one kilogram, because it is the kilogram. Unfortunately for Le Grand K and its identical twins, their masses have been found to be divergent, indicating that our definition of the kilogram has been shifting as well. So the question was - in this day and age, is it really acceptable to have transient definitions of our basic units of measurement? How would having units of measurement that are subject to change over time affect us in the near future? What about the far future?

To me, this felt very much like shift from the monetary gold standard to the fiat system we have in place. Money is money because we say it’s money, not because it is worth any amount of gold. Only in this case it’s “a kilogram is a kilogram based on the fundamental relationship between the energy (Planck’s Constant) and mass (E=mc²)”. This is the kind of forward thinking that will ensure our success as we develop ever more complex technologies and strike out toward new worlds. Both of which will rely heavily on the universality of our measurements over long periods of time.

The Bureau International des Poids et Mesures even put out a cool video about the vote. A little sensational, but it gets the point across.