The Tiny Donut That Proved We Still Don't Understand Magnetism

Imagine you're [music] in empty space and you fire off a stream of electrons. Well, then according to [music] most physics textbooks, the only way to change how those electrons behave is by applying an electric or magnetic [music] or gravitational force to them. But most physics textbooks are wrong. In the 1950s, two physicists came up with [music] a clever experiment.

You could have electrons travel through a region with no electric or magnetic fields whatsoever. And yet by flipping a switch, you could change their behavior. The magnetic field could be just zero. [music] And yet the presence of some quantity could actually lead to observable effects.

That wasn't supposed to happen, right? This experiment split the physics community in two. It made them question whether fields are fundamental [music] or whether something that was supposed to be just an abstract mathematical tool was actually more [music] core to reality. This tool was first introduced in an attempt to solve one of the hardest unsolved problems in physics, the threebody problem.

That is, if you have three bodies and you know their initial positions and velocities, how will they move under the influence of each other's gravity? It's a juicy juicy problem which has occupied literally generations, hundreds of hundreds of years of incredibly ambitious, talented mathematicians, physicists, and astronomers and and and beyond. The fact that this problem is so difficult to solve should at least be a little surprising because if you have just two bodies, then the solution is easy to find. In fact, the general case was already solved over 300 years ago by Newton himself.

But when [music] Newton added a third body, well, that's when everything fell apart. In the two-body case, the forces behaved predictably, always pointing toward the systems shared center of mass. But with three bodies, this is no longer the case. When you try to calculate the forces, they end up being extremely dynamic.

In addition to worrying about the magnitude of the forces, you also have to worry about their direction. So you end up with this chaotic mess of vectors. For the next 100 years, everyone who tried to solve this problem failed. But what if there was some other way to approach it?

A way to simplify the math and not have to worry about these three-dimensional vectors? Well, that's where Joseph Louie Lrangee comes ...