Molecular current hypothesis
Ampere's molecular current hypothesis could not be confirmed when there was little knowledge of the structure of the material at that time. It had a considerable speculative component; today it is understood that matter is composed of molecules, and molecules are composed of atoms, and atoms move around the core. From a modern point of view, the "molecular current" is composed of the orbital motion of each electron in the atom around the nucleus, the spin motion of each electron, and the spin motion of the nucleus. As a result, the ampere molecular current hypothesis has real content and has become an important basis for understanding the magnetic properties of matter.