“A careful analysis of the process of observation in atomic physics has shown that the subatomic particles have no meaning as isolated entities, but can only be understood as interconnections between the preparation of an experiment and the subsequent measurement.” -Fritjof Capra
For most living humans on the planet, the Standard Model and General Relativity, the theories that govern the four fundamental forces, have encompassed all of the known particles and their interactions for our entire lives. We know they can’t encompass all there is, but the search for the first particle beyond the Standard Model or the first force/interaction beyond the four known, understood ones has been elusive.
Ironically, it might not be a high-energy experiment that reveals the next step in understanding the fundamental nature of reality, but a low-energy, high-precision one. Last year, an experiment looking at the decay of an excited state of beryllium-8 noticed an excess of events at a particular electron/positron opening angle, perhaps indicative of a new particle and a new force. If the results hold up, this could change everything.