In 1790, amidst the fires, violence and decapitation of the French Revolution, The Marquis of Condorcet meets up with his four science bros – de Borda, Laplace, Lagrange, and Monge, and tells them: “You know what France needs right now?” “Hmm” “It needs the metric system bros.” By now, you’ve probably heard that the kilogram as we know it is dead and will be replaced next year, on May 20th, by its new definition. But what even is the kilogram and how did it come to be the International standard to weigh anything, whether it’s groceries or yo mama? Our story starts at the eve of the French Revolution. By then, France was far from Charlemagne’s standardized units, which used cutting-edge measurements such as the length of the outstretched arms of a large man. Instead, the French used 800 different units with a quarter million variations in function of towns, industries, or even on a trade by trade basis. So it was clear France, nay, the world needed a better system of measurement. And that’s where our five scientists come in. In 1790, “L’académie des Sciences” tasked them to come up with such a system, which they would do over the following year. After trying various alternatives, they settled on three core recommendations to define this new system of weights and measures. On March 1791, the French Assembly approved these recommendations, later thanked de Condorcet for his work by putting him in prison, where he would die before he could be guillotined, and task the Academy with his development. To do so, the Academy split the task into three parts. First: Find the meter. Second: Derive the grave from that meter. And Third: publish conversion tables to relate these new measurements to the 800 currently used. After the meter was incorrectly measured, Lavoisier and UEYE I can’t say it. AOU. HA-U. A-YOU. E-YOU. were able to derive the grave, which was later renamed ‘gramme’ after the Latin word gamma, which itself comes from the Greek word for letter – gamma. To thank him for his work, Lavoisier, per French customs, was later guillotined. On April 7 1795, the gram was defined in French law as the absolute weight of the volume of pure water equal to the cube of the hundredth part of a meter and at the temperature of melting ice; that is, zero degrees, which was later increased to four degrees since is the temperature at which water is its densest. However, they realized the gram was just too small to weigh yo mama and so added ‘kilo’ – Greek for thousand – for more practical uses. Hence why it’s the only measure of the Système International with a prefix, which was cool to know because I had always wondered why. In June 1799, a ‘Kilogramme des Archives’ was created, weighing precisely 18,827.5 grains, which the scientists then proudly showed to the world. only to be met, like a child showing his drawing to his mother, with indifference. Despite being made by law the sole system of weights in France, nobody used it, preferring the old system of measurements. And in 1812, a decade’s worth of work was totally gutted as Napoleon removed the law. But thankfully for the rest of Europe, the metric system and France’s male population, Napoleon didn’t last long. And it was reinstated such that by 1858, the metrication of the country had been completed. The “Kilogram des Archives” would be use another few decades before it was replaced by the International Prototype Kilogram, the IPK, in 1899. The new prototype was made of a platinum alloy and kept on the outskirts of Paris in the Bureau International des Poids et Mesures under two protective glass bells in a vote requiring three independent keys to open. Serious stuff! And for more than a century, the IPK, was good enough since it’s still the kilogram we use today. The problem is that over time, its mass is varied by 50 micrograms, which is the mass of a fingerprint and while that is not enough to explain how you took five kilos during Thanksgiving, it’s enough to impact the precision of scientific research. Evidently something had to be done. in 1960, the metre was redefined using a physical constant. And so in, 2005 at the 94th meeting of the International Committee for Weights and Measures, which apparently is a thing, it was recommended to do the same with the kilogram. In 2010, at the General Conference on weights and measures, which apparently is also a thing, it was noted that the kilogram could be defined using Planck’s constant, ‘h’. And after a few years of measurements and experimentation to ensure its viability, Planck’s constant was finally approved by the BIPM on the 16th of November 2018, as the new definition of the kilogram. Goodbye little platinum alloy with a weird yet necessarily degree of precision. You served us well. Hello everyone, I hope you enjoyed this video. If you did, please consider leaving a like, sharing, commenting and if you haven’t yet, subscribe. This was Barris! I will see you next week, but until then, Merde!