I Used 2 Know

Podcast Episode #15: I Used 2 Know- The Metric System was Coming

February 3, 2019

Time: 37mins
Launched: December 8, 2018


In this podcast episode we remember the 70s and how everyone in the US was going to convert to the Metric System. There were TV commercials trying to convince us to change, teachers would pound into us that we needed to learn the Metric System now, and thermometers, gas pumps and speed limit signs started to show metric equivalents.  But what happened? Listen to I Used 2 Know- The Metric System was Coming and find out why the US is still not using the Metric System, how secretly the US IS using the metric system, and how the world just redefined the kilogram last November, 2018.


Remember when our teachers back in the ‘70s warned us that we better learn the metric system because that was going to be the standard in the future?  If that was true, why are all of our measurements here in the US still different from the rest of the world?

Pounds instead of Kilograms…. Miles instead of Kilometers… Milk comes in Gallons but Soda comes in 2 Liter bottles?  What is going on?


The story of Noah in Genesis of the Old Testament.  

   Noah’s ark was measured in “Cubits” (approximately equal to the length of a forearm).

   That’s one of the earliest standards recorded..

1670:  Gabriel Mouton (vicar of St Paul’s Church in Lyons, France) proposed the first measurement system that would be based on the decimal system.  This idea would be expanded by the French Academy of Science and become the foundation of the Metric System!


1842:  Weights and Measures Act establishes the British Imperial System



Early America chooses the British Imperial System for purposes of trade with England.

1970’s  Great Britain starts to convert to Metric System to trade more easily with the rest of the world.  America is already on a path to follow suit except other factors intercede:

  1. Labor Unions were against changing because they feared it would lead to more globalization of trade and offshoring of jobs.
  2. The US felt the imperial measurements were part of our culture- and that learning thirds and quarters of ounces as well as decimal made us more diverse- like knowing a 2nd language.
  3. BUT most of all, the public didn’t care to change.


Best of both worlds:

1893, the United States in cooperation with the International Bureau of Weights and Measures officially defined our units of measurements (like the foot, pound, gallon) in terms of their Metric equivalent (meter, kg, liter).  SO, since 1893 the US has been using the metric system- we just convert everything again to our imperial measurements for the public.


  1. Acre Imperial
  2. Tonne Metric  (trick question… Imperial version is spelled Ton)
  3. Caldren Imperial (equal to 36 bushels of coal)
  4. Boulder Imposter
  5. Langley Metric  (measure of Solar Radiation)
  6. Einstein Metric  (a mole of Photons)


Mixing Imperial Units with Metric Units can cause real world problems;


  1. Mars Environmental Probe wound up burning up in Mars’ atmosphere due to mixed units in the design and software used on the project
  2. During a computer system outage, airplane pilots had to calculate their required fuel for a flight by hand.. Their calculation was in Kilograms of fuel… their fuel delivery was in Pounds… which then caused them to run out of fuel halfway into their flight!

On Nov 16, 2018 representatives of 60 nations including the US gathered in Versailles, France and changed the definition of the Kg. It is no longer this chunk of metal- this cylinder of platinum and iridium.  The kg is now defined in terms of Planck's constant, which describes the smallest possible unit of energy. And since Einstein created an equation that relates energy and mass together… we can define mass by a universal energy constant of nature!  

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