g2

This entourage influences the behavior of existing particles, including a property of the muon called its magnetic moment, represented in equations by a factor called g. According to a formula derived in 1928 by Paul Dirac, the English theoretical physicist and a founder of quantum theory, the g factor of a lone muon should be 2.

But muons aren’t alone, so the formula must be corrected for the quantum buzz arising from all the other potential particles in the universe. That leads the factor g for the muon to be more than 2, hence the name of the experiment: Muon g-2.

The extent to which g-2 deviates from theoretical predictions is one indication of how much is still unknown about the universe — how many monsters, as Dr. Polly put it, are lurking in the dark for physicists to discover.