THE first thing you need to know is that virtual particles, which are impossible to avoid if you want to understand how the fundamental forces of nature animate matter, aren’t really particles at all.

A clever mathematical tool known as virtual particles unlocks the strange and mysterious inner workings of subatomic particles. What happens to these particles within atoms would stay unexplained ...

So one of the strangest concepts I've come across in physics is the quantum vacuum. Or rather the apparent affect that empty space isn't empty. That the explanation right now is "virtual particles" ...