Avogadro constant of molecules in one gram-molecule of oxygen (exactly of oxygen, according to the definitions of the period), and this term is still widely used, especially in introductory works. The change in name to "Avogadro constant" ("N") came with the introduction of the mole as a base unit in the International System of Units (SI) in 1971, which regarded amount of substance as an independent dimension of measurement. With this recognition, the Avogadro constant was no longer a pure number, but had a unit of measurement, the reciprocal mole (mol). While it is rare to use units of amount of substance
Stoic physics Stoic physics Stoic physics is the natural philosophy adopted by the Stoic philosophers of ancient Greece and Rome used to explain the natural processes at work in the universe. To the Stoics, the universe is a single pantheistic God, but one which is also a material substance. The primitive substance of the universe is a divine essence ("pneuma") which is the basis of everything which exists. This "pneuma", which is the active part or reason ("logos") of God, provides form and motion to matter, and is the origin of the elements, life, and human rationality. From their physics, the Stoics