Zero Point Energy

Zero-point energy is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly fluctuate at their lowest energy state as described by the Heisenberg uncertainty principle. The empty space of the vacuum has this property. 

According to quantum field theory, the universe can be thought of not as isolated particles but continuous fluctuating fields. All fields have zero-point energy. But these fields cannot be a physical medium if it is to be Lorentz invariant such that there is no contradiction with Einstein's theory of special relativity.

Richard Feynman and John Wheeler calculated that the zero-point radiation of the vacuum was so powerful that even a small cup of it would be enough to set all of Earth’s oceans to a boil. But Albert Einstein’s theory of general relativity suggests zero-point radiation would “gravitate” — spreading out throughout the universe and be mitigated.

Then it was found that two negative energy surfaces in close proximity prevents the dilution of the zero-point energy, prevents it from “gravitating”. Thus, the energy can be gathered and used immediately or stored for later use.