Saying goodbye to an old measure

The author documents the 26th Meeting of the General Congress of Weights and Measures, Versailles, France. Photo by Amy Young
Author Amy Young, across the street from the delegates’ vote
Photo courtesy Amy Young

VERSAILLES, FRANCE — I’m video recording on three DSLR cameras today, which is the most I can handle by myself. But I don’t want to miss a second of this event, because I flew to Paris the day before yesterday just to film this auditorium of international delegates. These serious-looking men and women are actually very excited. I know this because several of them told me so. In a few minutes, they will cast their nation’s vote on whether to accept the proposed redefinition of the kilogram.

As of this morning, a kilogram is still defined as the mass of a very special platinum-iridium cylinder made in 1889, called the International Prototype of the Kilogram. If the vote passes, then starting May 20, 2019, 1 kilogram will instead be based on a value of Planck constant, one of the so-called fundamental constants of physics. Like the speed of light, the Planck constant governs how material behaves uniquely in our universe.

The platinum-iridium cylinder was the standard kilogram for all metric measurements in the U. S. Known as Kilogram No. 20, it was a copy of the International Prototype Kilogram, which was preserved at the International Bureau of Weights and Measures at Sevres, France.
Photo courtesy National Institute of Standards and Technology

Theoretical physics isn’t my background, but I’ve been working with a physicist for my documentary for several years, and now I can talk the talk – a little. My background is in architecture and the arts. In fact, location scouting yesterday after my arrival, I recalled my first visit to Versailles, my junior year abroad in the U. of I. School of Architecture.

Young takes test shots of the Palais des Congres the evening before the delegates’ vote.
Photo by Amy Young

The vote today takes place in the Palais des Congres, a conference center across the street from the renovated royal stables, my former classrooms. There I learned that the famous building is technically a chateau, despite its grandeur. A tourist sees my tripod and camera gear and asks if I’ll take his photo in front of the “palace.” I quickly oblige, resisting the urge to get a better shot for him.

This is my fourth trip to Paris to make my documentary film about the kilogram. It’s also my last trip, because this vote is the final sequence of my film. The vote also begins a new chapter in the kilogram’s story.

Walking around Paris, I see many reminders of the French Revolution: monuments, plaques, street names, paintings. But one outcome of the Revolution is something we use every day around the world: the metric system.

Amy takes test shots before the delegates’ vote.
Photo courtesy Amy Young

The mass unit for the early metric system is called the Kilogramme des Archives, made in the 1790s. I filmed it, but I didn’t handle it. Stored in its leather box, lined with red velvet and labeled with dates from the Revolutionary calendar, the object is alluring, but imposing. The simple cylinder looks like something from the modernist German art school, the Bauhaus, but then I recall it was the first ever “kilogram” and, through calibrations over 220-plus years, the foundation for all of our current commercial mass measurements.

Young watches the lectures, including two from Nobel Laureates.
Photo courtesy Amy Young

Several metrologists have called today’s proposal the biggest change to measurement since the French Revolution. If the vote passes by a majority, there will be no more units defined through elegant, durable, human-made artifacts like platinum cylinders, but rather through two Nobel-winning theories of modern physics.

While science builds on the past, it has no time for nostalgia. The framers of the early metric system, Laplace, Condorcet, and Lagrange would be the first to revise their original implementation.

The final vote is simple – the country name is called and the person shouts out “YES” or “OUI”. The decision is unanimous and is followed by a round of applause.

Editor’s notes:

Amy Young works for the physics department at the U. of I. She also is making a feature-length documentary, ‘The State of the Unit: the Kilogram,’ detailing the history, science and future of the kilogram. The work is intended for a broad audience.

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Source: Illinois News Bureau


Saying goodbye to an old measure
Article Name
Saying goodbye to an old measure
VERSAILLES, FRANCE — I'm video recording on three DSLR cameras today, which is the most I can handle by myself. But I don't want to miss a second of this event, because I flew to Paris the day before yesterday just to film this auditorium of international delegates.