Among the many tricky concepts which the layperson has to grapple with when learning about particle physics is something called “virtual particles”, which show up in cute pictures called “Feynman diagrams” along with “real particles”. In most books for the public, some words are mumbled about the uncertainty principle and how virtual particles are particles that exist for a short time and then disappear. Well, this isn’t really wrong, and it is the language that physicists use. But I have found that the language is so misleading for non-experts that it leads to many confusions among my readers. For this reason, I’ve taken a different tack in this pedagogical article, with the thinking that the most important thing for a layperson to understand about virtual particles is that they really are not particles at all, despite the name, and they don’t behave that much like them. They are more of a generalized disturbance in a field, while a real particle, a nice ripple in a field, is a special one.
Why would you want to read this article? Because in addition to the Cohen-Glashow argument against the OPERA experiment’s result on superluminal neutrinos, which appeals to a process similar to Cerenkov radiation, there’s a more powerful, but more subtle, argument that involves virtual particles. I’ll explain that in my next post.