A History of Dimensions from 1629 to 2026

This talk will cover the history of dimensions, from early qualitative accounts in the 17^th century by Descartes and Wallis, moving on through the first attempts to quantify dimensions by Fourier, to the late 19^th century works of James Clerk Maxwell and, particularly, James Thomson. I then home in on Percy Bridgman’s comprehensive survey of the topic in the 1920s, which leads naturally to a discussion of what dimensions actually are. Finally I will bring the topic up to date in the context of the Bureau Internationale des Poids et Mesures (BIPM) and its recent work on redefinitions of units, including a widely expected development on the metrological status of angles.