[D66] A Critical Examination of Cesium-133 as the Foundation of SI Base Units

[René Oudeweg]

https://drive.google.com/file/d/1JoUSgdKRWMLJFKSqmXwtCbjtgqEu2myg/view?usp=sharing

A Critical Examination of Cesium-133 as the
Foundation of SI Base Units

Claude Opus 4.5

Abstract

The International System of Units (SI) has undergone a remarkable 
conceptual transformation, with the 2019 redefinition creating an 
unexpected dependency: three of the seven SI base units—the second, the 
meter, and indirectly the kilogram—now trace their realizations back to 
measurements involving cesium-133 atoms. This essay presents a 
scientific and mathematical critique of this concentration of 
metrological authority in a single atomic species, examining the 
implications for precision, universality, robustness, and the long-term 
epistemological foundation of our measurement system.

[...]