The Seven Measures of the World

Martin, a physics professor at the University of Padua, makes his English-language debut with this stimulating exploration of the nature of measurement from prehistory to the present. He digs into the history of seven units: the ampere (electric current), the candela (“luminous intensity”), the kelvin (temperature), the kilogram (mass), the meter (length), the mole (“base unit of amount of substance”), and the second (time). On measuring distance, Martin observes that ancient Egyptians used standard lengths of rope to determine precise boundaries for land claims (ensuring administrators knew whom to tax) and that French Revolution-era egalitarians introduced the meter as a universal constant to replace local measurement systems that “often favored the few who managed them.” Among other fascinating tidbits, Martin notes that one of the first calendars is thought to be a 10,000-year-old rock bearing 28 notches representing the days in a lunar month and that Qin Shi Huang, “the first emperor of unified China,” led one of the earliest efforts to establish a centralized and uniform system of weights. The examination of the historical forces that produced the seven measurements is incisive and the bounty of trivia enlightens. It’s a revealing chronicle of how humans quantify the world. (June)