The State of the Unit: a documentary film about the redefinition of the kilogram

This forthcoming documentary series traces the fascinating history of the kilogram, the redefinition, and features interviews with the guardians of the prototypes. Scientists around the world chase the realization of a 200-year-old challenge: to create a mass standard that will never change with time, or space.

Status of the film September 2021: I've decide to turn the "Kilofilm" into a series! I think there are too many interesting people, ideas, and aspects of the kilogram to arbitrarily toss them out to only show the "important parts". The current edit is 244 minutes of running time, from 260 hours of raw footage. That makes about one minute per hour (60:1) which is a common ratio in documentary films. (I wasn't aiming for that ratio, but that how it turned out.)

Turning the material into episodes doesn't mean that there's a "physics" episode, or a "history" episode. The past story of the kilogram informs the present state of the unit. So I've arranged the episodes instead to express one definition (or conception) of the kilogram over time. For example, the first episode looks at how the IPK was developed and why; that is, the Kilogram of 1875-2018. The second episode looks at the kilogram as the bottom of the traceability chain of weights in commerce. The third episode looks at the kilogram as one of the French Revolutionary reforms to an inefficient commerce infrastructure. You get the idea.

Background on the kilogram In 1780, more than 40,000 different measures of length were in use in France for trading wool, corn, wood, all household staples. Every city and village had their own carved stone trade measures, stored at the local church.

The varying measures led to serious economic and trade problems, adding to the atmosphere of unrest in France. So, in 1787 King Louis XVI charged the French Academy of Science with the creation of a uniform set of measures.

In June 22, 1799 the meter and the kilogram were realized as physical objects; today these are kept secure at the International Bureau of Weights and Measures (BIPM) in Pavillon de Breteuil near Paris. The kilogram is stored under multiple glass lids; a speck of dust changes the kilogram's weight a tiny bit.

All current science and technology could not exist without the kilogram prototype, and the modern world needs a standard that is the everywhere the same. To realize this, the General Conference on Weights and Measures may redefine the kilogram as the calculated value of the Planck constant, the very same constant that revolutionized 20th-century physics in the form of transistors and computers. Today the speed of light is no longer a measured quantity, but rather a fixed value that implicitly defines the meter. Similarly, the Planck constant would define the kilogram and make the physical kilogram obsolete.

Since the retirement of the meter, the kilogram prototype is the only human-made measurement standard. Forever it will be for science what Cervantes did for literature and Goya did for painting: the foundation of modern instances.

And one hundred years from today, the kilogram prototype might well become mankind's most treasured artifact.

Director’s statement

My current film is about the kilogram. When I tell people that, some ask "What is there to say about the kilogram?" And others wonder, "How can you fit everything in only one film?"

Well, I had in mind a shorter film about how The Kilogram (a specific platinum-iridium cylinder in a vault in Paris) is losing weight, and what that really means.

But I found there's much more to the story.

In my film, I aim to bridge measurements from daily life to these efforts to re-define the kilogram at some of the major scientific players including NIST in Gaithersburg, CNAM and LNE in Paris, and PTB in Braunschweig, Germany. With this new definition, they hope to fulfill a 100-year-old dream of some of the greatest physicists of all times. And I aim to show the social and cultural relevance behind our measures.

I hope that you find the history and redefinition of the kilogram as fascinating as I do.

About the Director

Amy Young graduated from CalArts with an MFA in Film Directing. She began work on the The State of the Unit as part of an documentary film exchange program at La Fémis in Paris, France.