Electromagnetism Derived From Geometry

General relativity teaches that gravity is a manifestation of geometry. Not everyone knows that electromagnetism and the other fundamental forces (strong, weak) are similarly geometric.

Historically this dates back to Weyl and Kaluza-Klein, a century ago. But those theories were flawed, so a lot of physicists think that the geometry did not work.

Here is a new video that explains it well: Electromagnetism Derived From Geometry!.

In short, you add a circle to each point of spacetime, connect the circles infinitesimally to nearby circles, and then the electric and magnetic fields become the curvature.

The video tries to relate this idea to string theory, but that is speculation that did not pan out. The idea is completely essential to the Standard Model of physics, and our best explanation of the fundamental forces.