Current theories to describe the fundamental forces and particles of nature rely on beautiful symmetries known as gauge symmetries. These aren't easy to describe, but the renowned physicist Juan Maldacena, of the Institute of Advanced Study in Princeton, has developed a great analogy: he thinks of space as a grid of countries and of particles as travellers keen on making money by speculating with currencies. The analogy even explains the existence of the famous Higgs boson — and you don't need to be familiar with exotic quantum field theories to understand the picture. This collection of short articles will take you through the analogy. Or if you prefer, you can watch Maldacena explain the analogy in the video below. Enjoy!

A brief introduction to electromagnetism — A quick look at the force that gives us magnets and keeps the lights on. You don't need to understand it in detail, a few pointers are sufficient.

The economic analogy — This article provides the setting for our economic analogy: a grid of countries travelled by currency speculators.

Electromagnetic economics — If you've ever changed money when going on holiday, you know enough to understand the gauge symmetry of electromagnetism.

This sums up the economic model for the force of electromagnetism. But there's more! The following articles look at a similar theory for the weak nuclear force, which can be described using the same analogy.

The weak force and massive particles — A quick introduction to the weak nuclear force and its gauge symmetry, and why currency speculation implies the existence of massless particles. That's a problem because those particles aren't observed in nature.

The Higgs mechanism — A mechanism named after the physicist Peter Higgs, which allows our metaphorical speculators to speculate on the price of gold, gives those massless particles mass.

The Higgs boson — And here it is: the famous Higgs boson arises once you introduce silver into the picture. Its existence was predicted long before it was actually discovered at the Large Hadron Collider.

For the slightly more advanced here is a mathematical appendix in pdf format.

(Note that the analogy between foreign exchange and lattice gauge theory was noted in K. Young, Foreign exchange market as a lattice gauge theory, American Journal of Physics 67, 862 (1999). )

These articles contribute to our Stuff happens: The physics of events project.