I recently went to The Daresbury Laboratory for a meeting on the Low-Energy Frontier of High Energy Physics. The Low-Energy Frontier is the idea that small scale experiments can tell us about high energy physics by doing low energy measurement with extreme precision. This is in contrast to particle coliders which study high energy physics by producing particles with very high energies and then smashing them together to make a big mess and looking for new particles in that mess.
Low energy experiments are much smaller and cheaper than particle colliders, and yet they can put very stringent constraints on high energy physics. Their downside is that each individual experiment can only look for one very particular type of new physics, whereas a particle collider, in principle, can cover all the different possibilities at once (if you know what to look for).
One type of low-energy frontier experiment that I find very exciting are the attempts to shine light through walls. If there are new types of particle, called axion-like particles (ALPs), that interact with photons then in a magnetic field a photon from a laser beam can change into an ALP. Then it turns out that ALPs can pass through walls which are impermeable to photons. On the far side of the wall you use another magnet to transform the ALP back into a photon which you then try to detect with a very sensitive camera. No one has seen light shining through walls yet but many experiments, including a new one at the Daresbury laboratory which uses microwaves instead of laser light, are trying hard.
It was a great meeting, but slightly spoiled by the ratio of men to women being 23:1 (and I was the 1).