We live in a quantum universe; a universe where you can never be quite sure about anything. At the tiniest of scales, subatomic particles fizz and pop into existence, briefly experiencing the world of the living before returning back from where they came, disappearing from reality before they have a chance to meaningfully interact with anything else.
This phenomenon has various names: the quantum foam, the spacetime foam, vacuum fluctuations. This foam represents a fundamental energy to the vacuum of spacetime itself, a bare ground level on which all other physical interactions take place. In the language of quantum field theory, the offspring of the marriage of quantum mechanics and special relativity, quantum fields representing every kind of particle soak the vacuum of spacetime like crusty bread dipped in oil and vinegar. Those fields can’t help but vibrate at a fundamental, quantum level. In this view, the vacuum is singing to us, a harmony underlying reality itself.