The muon g-2 anomaly might be the biggest crisis in physics since quantum mechanics. This particle—basically a heavy electron—is wobbling differently than the Standard Model predicts. And that tiny difference could reveal an entirely new force of nature. The muon g-2 anomaly might be the biggest crisis in physics since quantum mechanics. This particle—basically a heavy electron—is wobbling differently than the Standard Model predicts. And that tiny difference could reveal an entirely new force of nature.