Iop Concise Physics

Weights and measures form an essential part of our ingrained view of the world, whether we realize it or not. It is just about impossible to function effectively without some internalized system of measurement, which enables us to estimate and judge size, weight, duration, distance and value. Our world is measured and calibrated, and we are all subject to the tyranny of these numbers and their associated units. Just try having a conversation without using vocabulary that references quantities or systems of weights and measures. In this volume, I outline a history of the science of measurement, and the origin of the world's measurement system; the Metric System. Today, the Metric System is known as the International System of Units or the 'SI' from the abbreviation of its official French name, Systeme international des unites. The reader will discover how the turbulent early history of the Metric System owed more to revolutionary politics than to good science clearly communicated to the people for whom the new units were intended. The simplicity and coherence of the Metric System is outlined, and we see how a system of weights and measures, based on only seven fundamental quantities, can be used as the basis of all science; the means of defining the make of all things. The history outlined here also demonstrates how the failure of communication during the unsuccessful initial introduction of the Metric System in 1795 is still of relevance. In a contemporary parallel, we will soon witness a redefinition of four of the seven fundamental quantities upon which the SI is based. This re-invention of the SI is being organized through agencies created in 1875 to oversee the original Metric System and its use by all nations. But are such agencies still fit for purpose? The four base quantities of mass, electricity, temperature and amount of substance will be redefined in such a way as to put them on a sounder scientific basis, but which will render them nearly incomprehensible to even an informed observer. This change in how we all define a number of fundamental quantities could come as soon as 2015, and will not be subject to any discussion or appeal. Humanity will be presented with a fait accompli. What will this mean for us?"