Maxwell Equations
~2 mins read
Maxwell had made one of the great unifications of physics. Before his time, there was light, and there was electricity and magnetism. The latter two had been unified by the experimental work of Faraday, Oersted, and Ampère.
Then, all of a sudden, light was no longer “something else,” but was only electricity and magnetism in this new form, little pieces of electric and magnetic fields which propagate through space on their own.
How can this bundle of electric and magnetic fields maintain itself? They cannot help maintaining themselves. Suppose the magnetic field were to disappear. There would be a changing magnetic field which would produce an electric field. If this electric field tries to go away, the changing electric field would create a magnetic field back again.
So by a perpetual interplay—by the swishing back and forth from one field to the other—they must go on forever. It is impossible for them to disappear.1 They maintain themselves in a kind of a dance—one making the other, the second making the first—propagating onward through space.
https://www.feynmanlectures.caltech.edu/II_18.html
https://en.wikipedia.org/wiki/Maxwell%27s_equations