The birth of electromagnetism (1820)

It is oddly fitting that the birth of electromagnetism, and an entirely new direction in physics, started with the tiniest twitch of a compass needle. In the year 1820, Danish physicist Hans Christian Oersted (1777-1851) observed the twitch of said compass needle in the presence of an electric current, providing the first definite evidence of a link between electricity and magnetism that would set the tone for much of modern physics.

The story of Oersted’s experiment is the stuff of physics legend, but like most legends it is often misremembered and exaggerated. Nevertheless, it is a fascinating piece of work and a piece of scientific history worth recounting.