An old-is-new-again approach to fundamental physics
Pretend you know absolutely nothing about how a car works. (Maybe you don’t have to pretend – I know I don’t.) How might you go about figuring it out? Here’s an idea: smash two cars together and take a look at the carnage. This might give you some clue about the interior workings. Maybe you’ll find the engine, axles, brake pads, etc. If you smash the cars even harder, maybe the engine itself will fall apart and you’ll find pistons and a crankshaft.
Sounds ridiculous? Well, this is more-or-less how modern high energy experimental physics works. Particles are accelerated to tremendous speeds and smashed together in colliders in order to analyze the particles that are created as byproducts. This actually works really well. A lot of important and fascinating new physics has been discovered this way. The problem is that in order to learn more and more using this method, you need to collide particles at higher and higher energies, and this is really hard (and expensive!) to do.
But there’s another way to figure out how a car works: you could pop the hood and examine it with a magnifying glass. Sure, you could only look at one small part at a time, but you could get a really good look.
This is one of the great motivations for doing precision measurements. By performing very careful measurements you can get a close up look at the inner workings of particles. Searching for subtle deviations from the results that physics as-we-know-it would predict is a great way to discover exotic new physics.
These experiments don’t require kilometeres-long tunnels or massive apparatus. In fact, they usually fit on a single table in a lab, reminiscent of the early days of experimental physics, and they’re becoming more and more popular as scientists turn to precision measurements to probe more deeply into fundamental physics. These tabletop experiments might be small in scale but they’re big in impact!