Technically, what you’re referring to here are not simply virtual particles—they’re a particular kind of virtual particle known as a ‘vacuum bubble’.
Virtual particles are any particles in a Feynman diagram that don’t extend off the side. They’re permitted to have different amount of energy than you’d expect from applying special relativity to their rest mass and momentum. In vacuum bubbles, there are no particles that extend off the side.
Technically, what you’re referring to here are not simply virtual particles—they’re a particular kind of virtual particle known as a ‘vacuum bubble’.
Virtual particles are any particles in a Feynman diagram that don’t extend off the side. They’re permitted to have different amount of energy than you’d expect from applying special relativity to their rest mass and momentum. In vacuum bubbles, there are no particles that extend off the side.