Danish physicist and philosopher who, in 1819, discovered the deflection of a compass needle while performing a demonstration for his students. This discovery of a fundamental connection between electricity and magnetism rocked the scientific community and led to a flurry of activity in electrodynamic research by such investigators as Ampère and Arago. After all, the magnetism produced by a current would generate a force. Forces are capable of producing motion, so motion could come about which would lead to a current. While this is not a conservation law, it is a statement about the fundamental interconvertibility of natural phenomena.

It it is often stated that Oersted's was completely accidental and spontaneous. That contention is, however, misleading. Oersted had studied Naturphilosophie under Schelling himself, and wholeheartedly adopted the view that nature is systematic and unified. (He also thought that the practice of science is a religion.) The fact that he should be seeking a connection between electricity and magnetism was motivated entirely because of his prior philosophical conviction that one must exist. After all, only someone looking to find a connection between electricity and magnetism would consider placing a compass, only affected by magnetic fields, near a current -carrying wire, thought to be a purely electrical phenomenon, in the first place.

Oersted's experiment showed that there were underlying connections between what appeared to be quite different physical phenomena, and encouraged other scientists to seek them out. While universal convertibility is not the same as conservation, the two are nonetheless closely related. Thus, a connection or conversion between different phenomena, especially two as outwardly dissimilar as electricity and magnetism, was step towards a unified concept of energy.

Ampère, Arago