The mathematician David Hilbert (1862-1943) said that you should be able to explain your theorems to the Man on the Street. I wonder if the rule applies to our quantum-based defintions of our units. 2:34 min

An important aspect of science today, including high-level science, is how much debate, opining and compromises happen when creating a final policy put forward by an international committee.

It isn't easy in a film to show the debate taking place live (often in private meetings) or via volleys of scientific papers, which aren't terribly cinematic unless they're at least 200 years old.

So Episode Seven presents my "constructed discussion" on two questions: Should the average person be able to understand the basis of their weights and measures? Can the average person understand the New SI?

Barry Taylor (NIST Scientist Emeritus) and I discussed the understandability of the New SI, and whether it matters. The CODATA Task Group on Fundamental Constants was formed 1969. At that time, Barry was already researching fundamental constants. In 1973 he co-published CODATA's report "The 1973 Least‐Squares Adjustment of the Fundamental Constants." [1]

Barry witnessed and took part in the redefinitions and revisions of several units: the kelvin, the second, the meter. He defends the re-definition of the kilogram as not harder than the other definitions, and asks rhetorically, "The so-called 'Man in the Street,' what does he know about the triple point of water?"

Barry Taylor is referencing David Hilbert's (1862-1943) talk at the 1900 International Congress of Mathematicians. Hilbert claimed, "An old French mathematician said: ‘A mathematical theory is not to be considered complete until you have made it so clear that you can explain it to the first man whom you meet on the street." According to “The first man on the street”—tracing a famous Hilbert quote (1900) back to Gergonne (1825)," Hilbert and others were thinking of projective geometry, theories, and mathematical optics [3]. It is Barry Taylor who applies the test to metrological standards.

Because I don't know what people know, I found two Men on the Street. In this clip I ask what they know about the definitions of the kelvin and the second.

Note that there are many scientifically-aware people on the streets of Champaign-Urbana.