Cookbooks, Kilos, and Communications

By Dick Bourgeois-Doyle


"Goodness, does this mean I have to buy all new cookbooks?"

My mother-in-law’s question confirmed my failure to describe the redefined kilogram and its importance. On November 16th (2018) in Versailles France, member states of the Convention of the Metre voted unanimously to change the world’s measurement system, notably the definition of the kilogram, the touchstone for calculating mass. Experts say the move constitutes the most profound measurement change in over a century.

My desire to share this science story with friends and family flowed from knowing that the big decision would not have come as quickly without work at the National Research Council of Canada (NRC) labs in Ottawa.

For almost 130 years, the world based its definition of mass on a physical object: a shiny platinum-iridium cylinder kept at the International Bureau of Weights and Measures in France. The kilogram was defined as exactly equal to the mass of this piece of metal, dubbed "Le Grand K." Referencing an artefact like this seemed practical in the 19th century when the same concept was applied to length and time (if one considers the spinning earth as an artifact). But it was imperfect. If, for example, the reference kilogram cylinder changed slightly with micro-deterioration, chemical processes, or an errant sneeze, it would affect the system of measurement globally.

As technology advanced, other measurement artifacts were replaced with reliance on physical constants: definable quantities believed to have fixed values independent of time and space. Length is now determined with reference to the speed of light, and time is measured with clocks locked on the atomic transitions in the cesium-133 atom.

But the quest to replace Le Grand K with a physical constant proved more of a challenge.

Thanks to Einstein’s E=mc2 insight, scientists have long known that energy and mass are intertwined. But to apply this recipe in mass metrology, scientists needed an energy value that would hold up in all circumstance. The chosen standard, known as the Planck Constant, is a quantum measure relating the energy of a photon to its frequency.

Though widely accepted as the desired reference point, it proved very difficult to establish with enough precision to meet the kilogram requirements. The quest to fix Planck’s constant became a celebrated "Frontier Science" project, deemed "one of the most difficult experiments in the world" on the level of finding the Higgs boson particle.

Nevertheless, a decade ago, scientists at the NRC metrology labs were inspired to believe they could succeed on a shoestring. They knew that the Planck Constant could be best determined with a device – now called a Kibble Balance for its originator Bryan Kibble of the UK National Physical Laboratory (NPL). In 2008, the NPL abandoned its effort at sufficient accuracy for the Planck Constant experiment, and learning of this, NRC acted quickly to acquire the NPL’s balance for Canada.

The NRC team redesigned the experiment with a suite of innovations that led to a world record for the smallest uncertainties in the determination of Planck’s Constant, helping pave the way to the November decision in Versailles.

All very exciting for the science communications geek in me, but, as I learned, not so much for people who don’t read blogs like this over morning coffee and limit their measuring interests to cookbooks, bathroom scales, and bananas at the grocery store.

So, I set out to see how others shared Le Grand K news with their audiences and to try to learn.


  • Reflecting the nerdy nature of Wikipedians interested in metrology, the Wikipedia article on the kilogram change focuses on the technical and only briefly mentions variations in Le Grand K as an explanation for the redefinition. I think Wikipedia’s particular contribution to the communication of the science of masses to the masses lies in its pop-up definitions and links that allow you to drill down as your personal knowledge base requires: though you do risk slipping into redefinition rabbit holes or, like me, onto the trails branching off the long, crazy list of things named after Max Planck.


  • I liked that PBS radio celebrated the Canadian role in its kilogram story. It featured Barry Wood, an NRC metrologist, who noted that the 1950’s decision to pin length to the speed of light paved the way for the development of GPS systems. PBS devotes its website sidebars to convincing our American friends that redefining the kilogram also implicates the weighing of things in pounds. Its story brands a rational, artefact-free measurement system "for all people, for all time" as "a profoundly beautiful thing," adding that if we ever want to communicate with space aliens, we should probably use universal constants.


  • Naturally, the BBC focuses its report on the UK’s NPL and its contributions. As for its efforts to communicate with the public, I liked the comparison of fluctuations of 50 parts in a billion to be on the level of the weight of an eyelash, presumably without mascara. Another BBC image helped me better understand the workings of the Kibble Balance. It likened the device to a large electro-magnet moving old cars around a scrapyard with its energy force adjusted to meet the demands of a vehicle’s specific weight.


  • Wired surprised me with a non-technical story of the human drama and emotion around the new kilogram. It talks of sweaty foreheads, crammed rooms, and anticipation at the big vote, but also of the sentimentality and sweet affection that some scientists felt for Le Grand K and its duplicates around the world. Physicist Patrick Abbott recounts the tension he felt whenever entrusted with the U.S. kilogram on verification trips to France, always taking it along to the bathroom and never letting it out of his sight. He said he felt like someone had handed him the keys to a Ferrari.

  •, billed as a champion of "explanatory journalism," devotes around 3,000 words to the new kilogram. Its story notes that Planck’s Constant starts with a decimal point followed by 33 zeros before you get down to business. The writer compares the Kibble Balance to a Victorian era "time machine … parked … in a brewery," and half way through heavy-lifting science he stops to ask readers: "Still with me?" Then, the web story links to a 25-minute podcast that teases out science issues in a dialogue format and with observations on the utility of the metric system in measuring marijuana.


  • In its report on the kilogram event, the National Institute of Standards and Technology (NIST), an agency of the U.S. government, acknowledges that the ultra-accuracy provided by the new system won’t help people watching their weight or buying produce at the supermarket. But NIST adds that the change will benefit "fields such as forensics, pharmaceuticals and experimental physics"and will affect the definition of quantities such as force and energy. Its story is rich in images, links, and charts. But I found it noteworthy for its quirky, staff-made video on how to build your own Watt Balance out of Lego.

India Today

  • The English language media channel India Today begins its website kilogram story with the phrase "It's official" followed by "The wait is finally over!" as if it was announcing national independence or some other widely understood and anticipated happening. I guess this is one approach: just act like your audience knows that the event is important and go from there. The site does help readers a bit by breaking up the pie charts, facts, and text with headers that pose straightforward questions like "Why is the kilogram redefined?," "How was it defined before?," and "How will it be defined now?"


  • After laughing at India Today, I found it humbling to see those words, "It’s official," atop our national broadcaster’s report. CBC just reposted an Associated Press (AP) wire story with no attention to the Canadian angle; Fox News did the same. The AP story adds a bit to public communications with phrases like "the heir and the spares" to refer to Le Grand K and its duplicates and "Future-proofed" to describe confidence in the new system. Resonating with the development of GPS systems, a quoted researcher calls the new kilogram a "springboard … to … pursue those things that we don't know."

Smithsonian Magazine

  • Smithsonian Magazine presents an exhaustive description of the history of precision measurement noting that it even had a featured place in the Magna Carta and has involved many great scientists and institutions. Its description includes special reference to the Canadian effort. The Smithsonian noted that in order to redefine the kilogram, the scientific community had to perform at least three experiments that calculated Planck’s Constant to an uncertainty of no more than 50 parts per billion. In a photo caption, it mentions in passing that Canada’s NRC team performed this feat to "within an uncertainty of 9 parts per billion."

The New York Times

  • The New York Times covered the story in a similar way with detail on the science, the importance of standards, and the role of the new kilogram in the process of "democratization." In this, the paper viewed the use of a universal constant and the severing of ties with an artefact as freedom. Very American. As a Canadian, I was heartened by the venerable paper’s reference to NRC’s role and its purchase of the NPL’s Kibble Balance in 2008. It quoted Dr. Kibble’s widow Anne, another scientist, saying that her late husband "would have been so very, very happy."

The Economist

  • I like The Economist’s semi-subjective, but fact-filled style. In the kilogram report, it applied this approach in recounting measurement history from the days when grains of wheat defined mass. The article did not pay too much attention to the science other than to cite the importance of the Planck Constant. Through the lens of public engagement, it stands out because of its accompanying illustration: a pudgy guy stepping from an old set of scales to one shaped like the atomic symbol. It tells those hoping "to effortlessly shed some weight before the festive season as a result of these changes will be disappointed."


  • Nature’s online report of the kilogram decision listed straightforward scientist-oriented facts. It included charts, and acknowledgement of the importance of being able to determine mass in n multiple ways, at any place or time and on any scale, without losing accuracy. Though not mentioned in this story, the Canadian angle had a high profile in some of the older reports linked to the main page. One from 2015 noted that in the long quest to establish Planck’s Constant, "the Measurement Science and Standards laboratory in Ottawa, part of Canada’s National Research Council (NRC), bought and rebuilt a watt balance originally constructed at the UK National Physical Laboratory" which constituted the "first sign of progress."


  • Science, the peer-reviewed journal of the American Association for the Advancement of Science, did indeed talk about science. But it also invoked the image of Le Grand K as an aging French monarch about to be dethroned in a gathering in Versailles with allusions to a scientific revolution and its origins in the French Revolution The Science report concludes by telling readers that the French will keep Le Grand K and will periodically calibrate it as a secondary standard, calling this "a fairly dignified end for a deposed French king;" certainly a better fate than the guillotine.

Globe and Mail

  • But my favourite report on the new kilogram came from the Globe and Mail and was written by one of our country’s best science journalists, Ivan Semeniuk. I am not sure that his comparison of the link between the kilogram and the Planck Constant to "a mathematical umbilical cord" is entirely apt, but I like his effort to explain the science and the attention he gives to the Canadians involved in the project. Like others though, he stresses that for most people it will appear that nothing has really changed. Ivan says that this is "precisely the point" but adds that the system behind our daily measuring will now "stand on firmer ground."

This may be an answer for my mother-in-law. You don’t need to replace cookbooks, but the home you cook, count, and measure in will be sitting on a solid foundation.

The point relates to the importance of consistency and universal standards in measurement which I think media coverage of the new kilogram addressed convincingly. But I also saw two other themes. One was an effort to explain the necessity of ultra-accuracy in terms that most people could appreciate. Aside from the GPS example, I don’t think we in the science communications community did such a good job. This may be because, like GPS, the benefits of a new kilogram lie in things that have yet to be imagined.

For me, however, the importance of establishing Planck’s Constant and a new reference for mass rests in its potential as an uplifting example of international collaboration in the pursuit of reproducibility and a universal truth in the so-called "post-truth era, and, of course, the Canadian connection to this effort to build a system "for all people, for all time" is also "a beautiful thing."

Other References

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