Most of us don’t think much about charging, except for those annoying moments when our phones run out of charge. But for physicists, it’s a big problem. In all atoms, negatively charged electrons orbit around a nucleus containing positively charged protons, and the entire dance is maintained by their mutual attraction. So it’s safe to say that the pricing couldn’t be more basic.
This explains why physicists have struggled for years to understand its properties, and have mostly succeeded. But there is one question that always remains hanging in the air and unanswered. The smallest possible unit of charge seems to be the electron. All other naturally occurring particles have only multiples of this. In nature, you’ll find charges of -1, +3, or -2, but you’ll never find a charge of 0.25. Why is this?
You might shrug and say that’s the way the universe is. But the truth is, there was always good reason to suspect the existence of fractional billing, even if it hadn’t already been discovered. And the question is particularly lively today, thanks to fresh insights from string theory, one candidate for a theory of everything.
Experiments are now underway at CERN’s particle physics laboratory near Geneva, Switzerland, in search of particles that may have a charge just 1/1000th that of an electron. If they can find them…
