Hard to quarrel with success. Well, see if journalist Crenson does any better. It pervades space and is necessary for electromagnetic and other fields to exist. In fact, it is only through these fields that the quantum vacuum is observable. But the vacuurn is still there, even if there is no field with it.
Virtual particles pop into existence for incredibly brief periods of time, then disappear again.
The virtual particles cannot be measured because they are not real particles, but they really are there nonetheless. Not real but really there. Hang on, we're not done yet. In the case of sonoluminescence, Eberlein suggests, virtual photons popping out of the quantum vacuum get converted into the real thing. According to quantum theory, virtual particles can be made real with the addition of a lot of energy.