Alessandro Conigli

The muon resembles the electron but is 200 times heavier and lives for two millionths of a second. Its magnetic moment, how the particle responds to a magnetic field, has been measured with fantastic precision. Yet the measured value is slightly larger than theory predicts.

Electric charge is not like a number chiseled in stone. In the vacuum around any charged particle, pairs of particles and antiparticles are constantly born and annihilated, like the foam in a glass of champagne. The bubbles screen the true charge, making it appear smaller or larger depending on how close we get.