For 15 years, there has been a mismatch in physics. A particle called the muon wasn't behaving the way theory predicted it should. A new theory and new experiment might solve this problem.
New particles or forces may exist that aren't accounted for in the standard model.
When scientists created the Higgs particle with protons, they needed the 10km-wide Large Hadron Collider. A muon machine could achieve it with a diameter of just 200 metres.
A particle physicist explains just what this keystone theory includes. After 50 years, it's the best we've got to answer what everything in the universe is made of and how it all holds together.