The first results from the Muon g-2 experiment hosted at Fermi National Accelerator Laboratory show fundamental particles called muons behaving in a way not predicted by the Standard Model of particle physics. These results confirm an earlier experiment of the same name performed at Brookhaven National Laboratory. Combined, the two results show strong evidence that our best theoretical model of the subatomic world is incomplete. One potential explanation would be the existence of undiscovered particles or forces.