In 1931, Paul Dirac traced a line of mathematics across a page and found, at its end, something no one has ever held in their hands — a magnet with only one pole. A north without south. A question the universe has not yet answered.
The equations were elegant. The symmetry was perfect. If electric charges can exist alone, why not magnetic ones? Dirac showed that a single monopole, anywhere in the cosmos, would explain why electric charge comes in discrete packets. One particle to justify a law of nature.